61 BMW 1983 R80ST Install Electrical System

I replace the main wiring harness and all the sub-harnesses. I also replace all the electrical components. Since this bike sat for almost 25 years and the components and wiring were not in good shape, replacing it all should provide very good reliability.  You can see how I remove what was left of the original electrical system here.

Parts

Here are all the electrical system wiring and components I install. All of these were graciously donated by Euro MotoElectrics in support of my goal of auctioning this bike and donating all the proceeds to the Motorcycle Relief Project.

Part #                   Description                                                                   Qty
61 11 1 244 096 WIRING HARNESS SECTOR CHASSIS, Main Harness 1
61 12 1 244 137 WIRING HARNESS TAIL LIGHT 1
61 12 1 244 138 WIRING HARNESS, BRAKE LIGHT SWITCH, REAR 1
61 13 1 244 090 WIRING HARNESS, BRAKE LIGHT SWITCH, FR 1
61 12 1 244 176 WIRE IGNITION COIL 1
61 12 1 243 523 WIRING TRANSMISSION-SWITCH 1
61 31 1 244 420 COMBINATION SWITCH LEFT 1
61 31 1 244 417 COMBINATION SWITCH RIGHT 1
61 31 1 244 070 STOP LIGHT SWITCH (from 09/80), Front Brake Switch 1
61 31 1 243 097 SWITCH, Transmission Neutral 1
61 31 1 243 414 OIL PRESSURE SWITCH – M12X1,5, Includes Washer 1
61 31 1 243 403 CLUTCH SWITCH 1
61 31 1 353 684 STOP LIGHT SWITCH, Rear Brake 1
61 31 1 373 588 MINI-RELAY, Headlight 1
61 36 1 389 105 RELAY, Starter Relay 1
62 14 1 243 581 LAMP – LEFT, Instrument Dash Turn Signal Indicator 1
62 14 1 243 582 LAMP – RIGHT, Instrument Dash Turn Signal Indicator 1
61 21 2 346 800 BATTERY, MAINTENANCE-FREE – 12V 19AH 1
61 21 1 233 028 RUBBER MOUNTING, Battery Box 4
61 21 1 243 562  ENSION STRAP, Battery Box 2

Here are the new engine electric components I install.

Part #                  Description                                                                   Qty
12 11 2 413 906 IGNITION SENSOR-Refurbished By EME 1
12 14 2 325 284 IGNITION CONTROL UNIT 1
61 12 1 244 176 WIRE IGNITION COIL, ICU To Ignition Sensor 1
12 13 1 244 426 IGNITION COIL 1
12 12 1 243 453 IGNITION WIRE 5K OHM 40 CM, Set w/ 2 Wires 1
12 12 9 062 594 SPARK PLUG – BOSCH W7DC,
NGK BP6ES Equivalent
2

Video

Here is a video summary showing how I install the electrical system.

VIDEO: 1983 BMW R80ST Install Electrical System

Bench Test Wiring And Components

I bench test the electrical wiring system before installing it. This lets me verify that almost every part of the wiring system is working, and if I find a problem, it’s easier to repair the problem before installing the main wiring harness and the electrical components on the bike. To start, I label all the connectors on the main wiring harness.

Main Wiring Harness Labels

Main Wiring Harness Labels

The main wiring harness comes with a wiring diagram and list of components,

Main Wiring Harness & Wiring Diagram

Main Wiring Harness & Wiring Diagram

Wiring Diagram Components List

Wiring Diagram Components List

The wiring diagram included with the main wiring harness indicates wire colors using abbreviations of the wire colors in German. That can be hard to comprehend. You can see what the abbreviations are for colors in this document.

The Haynes manual includes color wiring diagrams which can be easier to read. That said, for wires with two colors, the stripe color can be hard to determine from the diagram, so cross-referencing the wire with the wiring diagram included with the main wiring harness helps identify the two colors. Here is a copy of the R80ST wiring diagram from the Haynes Manual. Click the picture to enlarge it.

Wiring Diagram: R45, R65, R65LS, R80ST, 1981-1985 [SOURCE: Haynes Manual]

Wiring Diagram: R45, R65, R65LS, R80ST, 1981-1985 [SOURCE: Haynes Manual]

NOTE:
When I mention two colors for a wire, the first is the solid color and the second is the stripe color.

Once I have the main wiring harness connections labeled, I install the sub-harnesses, relays, switches and lights. Here is a picture of the electrical system, except I didn’t include the ignition coil and voltage regulator.

Electrical System Components-Except Ignition Coil & Voltage Regulator

Electrical System Components-Except Ignition Coil & Voltage Regulator

Left Handlebar Combination Switch

Left Handlebar Combination Switch

Right Handlebar Combination Switch

Right Handlebar Combination Switch

Rear Brake Light Switch & Sub-Harness

Rear Brake Light Switch & Sub-Harness

Front Brake Brake Light Switch & Sub-Harness

Front Brake Brake Light Switch & Sub-Harness

Rear Lights Sub-Harness

Rear Lights Sub-Harness

Handlebar Lever Clutch Switch Sub-Harness

Handlebar Lever Clutch Switch Sub-Harness

Transmission Neutral Switch & Oil Pressure Switch Sub-Harness

Transmission Neutral Switch & Oil Pressure Switch Sub-Harness

Tachometer Circular Socket-Center Has Half-Circle Orientation Slot For The Plug

Tachometer Circular Socket-Center Has Half-Circle Orientation Slot For The Plug

Tachometer Has Indicator Bulbs

Tachometer Has Indicator Bulbs

Speedometer Light At Top

Speedometer Light At Top

Original Speedometer With Actual Mileage

Original Speedometer With Actual Mileage

Ignition Coil

Ignition Coil

Voltage Regulator

Voltage Regulator

Neutral Switch

Neutral Switch

Oil Pressure Switch

Oil Pressure Switch

Turn Signal Relay

Turn Signal Relay

Headlight Relay

Headlight Relay

Starter Relay

Starter Relay

Headlight Wiring

Headlight Wiring

Instrument Cluster Wiring

Instrument Cluster Wiring

Then, I use the new R80ST battery and attach the RED battery (+) terminal in the main wiring harness to the (+) terminal of the battery and attach the frame ground to the (-) battery terminal.

Bench Testing Electrical System Before Installation

Bench Testing Electrical System Before Installation

I attach the frame ground ring terminal and the battery (-) terminal. I also attach a jumper wire to terminal (85) with the BLACK wire on the headlight relay and connect it to the battery (-) terminal so the headlight relay has a ground and I can test the headlights.

NOTE:
On this bike, the headlights come on when the ignition is put in the ON position. But, they go out when you press the starter button. The wire on terminal (85) on the headlight relay goes to terminal (87) on the starter relay and from there the connection continues to the starter solenoid. This provides a ground path for the headlight relay except when the starter button is pushed. Then there is power on terminal (87) of the starter relay which flows back toward the headlight relay which means there is no voltage difference across the relay coil, so it closes turning off the headlight.

I start by turning the ignition switch to the PARK  position and verify that the running lights and instrument lights are working.

Then I turn the ignition switch to the ON position. I verify that the headlight, turn signals, horn, and front and rear brake light switches work.

Next, I press the left transmission neutral switch to verify that the neutral light in the tachometer goes out.

I use a volt meter to verify the starter relay is working. I test the starter relay output terminal (87) is on when the neutral switch is open and the right handlebar switch is closed and the starter button is pressed on the left handlebar combination switch.

This bench testing doesn’t verify that the starter motor and solenoid are working, but I bench tested those earlier.

It also doesn’t verify if the ignition system and the charging systems are working. I’ll test those when I do the first engine start.

Install Headlight Bracket & Headlight Bucket

The top of the headlight bracket mounts on two shackles that fit under the fork tube top bolts.

Headlight Bracket Top Mounting Shackle

Headlight Bracket Top Mounting Shackle

Headlight Bracket Top Mounting Shackle

Headlight Bracket Top Mounting Shackle

Top Of Headlight Bracket Hardware Details

Top Of Headlight Bracket Hardware Details

M6 Bolt, Wave Washer And Cap Over Rubber Grommet At Top Of Headlight Bracket

M6 Bolt, Wave Washer And Cap Over Rubber Grommet At Top Of Headlight Bracket

Cap Over Rubber Grommet At Top Of Headlight Bracket

Cap Over Rubber Grommet At Top Of Headlight Bracket

Top Of Headlight Bracket Mounts To Shackles Under The Fork Tube Cap Nut

Top Of Headlight Bracket Mounts To Shackles Under The Fork Tube Cap Nut

The bottom of the headlight bracket mounts on two steel straps that attach to the bottom of the lower fork yolk and to the bottom of the headlight bracket.

Headlight Bracket Bottom Mounting Strap Detail

Headlight Bracket Bottom Mounting Strap Detail

Metal Strap Used To Secure Bottom Of Headlight Bracket To Lower Fork Yoke

Metal Strap Used To Secure Bottom Of Headlight Bracket To Lower Fork Yoke

 

M5 Bolts Secure Bottom Of Headlight Bracket To Lower Fork Yoke Using Steel Straps

M5 Bolts Secure Bottom Of Headlight Bracket To Lower Fork Yoke Using Steel Straps

Headlight Bracket Mounted

Headlight Bracket Mounted

Headlight Bracket Mounted

Headlight Bracket Mounted

I install the headlight bucket. It has two rubber washers; one fits against the headlight bucket and the other fits on the outside of the headlight ear of the headlight bracket. A bolt and large chrome flat washer secure the headlight bucket to the headlight ears.

Headlight Bucket Mounting Hardware Details

Headlight Bucket Mounting Hardware Details

Rubber Washers Go On Either Side Of Headlight Bracket Ear

Rubber Washers Go On Either Side Of Headlight Bracket Ear

Headlight Bucket Mounts With Bolt And Large Chrome Flat Washer With One Rubber Washer Under Chrome Washer

Headlight Bucket Mounts With Bolt And Large Chrome Flat Washer With One Rubber Washer Under Chrome Washer

Install Main Wiring Harness & Electrical Components

I start installing the main wiring harness starting from the front of the bike. I route it to the headlight, speedometer and tachometer, the ignition switch, the turn signal stalks and the dash turn signal indicator wires. Then I work my way toward the rear of the bike installing electrical components and connecting them to the main wiring harness.

The main wiring harness goes behind the headlight bracket. Toward the bottom there are tabs that I bend to hold the main wire harness in place.

Main Wiring Harness Routing Under Lower Fork Yoke With Headlight, Turn Signal, Ignition Switch and Dash Turn Signal Indicator Wires

Main Wiring Harness Routing Under Lower Fork Yoke With Headlight, Turn Signal, Ignition Switch and Dash Turn Signal Indicator Wires

Metal Arms On Back Of Headlight Bracket Clamp Main Wire Harness To Back Of Headlight Bracket

Metal Arms On Back Of Headlight Bracket Clamp Main Wire Harness To Back Of Headlight Bracket

Headlight

I insert the headlight socket and the BROWN and GREY-Black wires that go to the parking light inside the headlight shell. I insert the large rubber grommet into the hole in the bottom of the headlight shell.

Headlight Connectors Inside Headlight Shell

Headlight Connectors Inside Headlight Shell

I connect the socket to the three headlight terminals and the GREY-Black wire to the center terminal of the parking bulb socket and the BROWN ground wire to the outside terminal of the parking bulb socket.

Headlight Wiring Connections

Headlight Wiring Connections

I install the headlight reflector into the headlight shell and secure it with the tab and Phillips head screw that pulls the bottom of the headlight reflector tight against the headlight shell.

Allen Head Screw At Bottom Of Headlight Reflector Secures It To Headlight Shell

Allen Head Screw At Bottom Of Headlight Reflector Secures It To Headlight Shell

Temporarily Mount Speedometer & Tachometer

These attach to the top of the headlight bracket with two M5 studs that fit into holes in the headlight bracket. The speedometer is on the left and the tachometer is on the right as you sit on the bike. They fit into the dash. I’ll install them permanently when I install the handlebars and the instrument dash.

Headlight Bracket Has Holes For Mounting Speedometer & Tachometer

Headlight Bracket Has Holes For Mounting Speedometer & Tachometer

Instruments Have Bracket Attached With Studs For Mounting

Instruments Have Bracket Attached With Studs For Mounting

Instrument Mounting Detail

Instrument Mounting Detail

The speedometer has a bulb that illuminates the speedometer face. It pushes into a hole in the rear of the speedometer at the top.

Speedometer Light Bulb & Socket Installed In Back Of Speedometer

Speedometer Light Bulb & Socket Installed In Back Of Speedometer

The tachometer has all the indicator lights and connects to the main wiring harness with a round plug that has a raised half-circle in the middle that fits into a half-circle hole in the back of the tachometer so the plug connects to the correct pins.

Tachometer Circular Socket-Center Has Half-Circle Orientation Slot To Orient Circular Plug

Tachometer Circular Socket-Center Has Half-Circle Orientation Slot To Orient Circular Plug

Round Plug Goes Into Back Of Tachometer

Round Plug Goes Into Back Of Tachometer

Instruments Temporarily Mounted To Headlight Bracket

Instruments Temporarily Mounted To Headlight Bracket

Front Turn Signals

I push the turn signal wires–BLUE-Black (right) and BLUERed (left)–into the turn signal stalks behind the headlight bracket. I install the turn signal housings on the turn signal stalks. There is a notch in the stalks and a bracket inside the turn signal housing with a tab that fits into the notch locking the housing onto the stalk. The BROWN ground wire goes on the terminal attached to the side of the bulb and the wires go on the terminal attached to the center of the bulbs.

Turn Signal Wire Routing Behind Headlight Bracket

Turn Signal Wire Routing Behind Headlight Bracket

Front Turn Signal Wires Extend Through Tube Of Turn Signal Stalks

Front Turn Signal Wires Extend Through Tube Of Turn Signal Stalks

Notch In Turn Signal Stalk

Notch In Turn Signal Stalk

Bracket That Secures Turn Signal Housing To Turn Signal Stalk

Bracket That Secures Turn Signal Housing To Turn Signal Stalk

Wires Attach To Turn Signal Terminals

Wires Attach To Turn Signal Terminals

"TOP" On Turn Signal Lens

“TOP” On Turn Signal Lens

Ignition Switch & Turn Signal Indicators

I route the ignition switch wires so they are below the hole in the headlight bracket that the ignition switch fits into. I route the two sets of turn signal indicator wires so the BLUE-Black is on the right and the BLUERed is on the left side of the ignition switch as you sit on the bike.

Ignition Switch Wires

Ignition Switch Wires

Dash Turn Indicator Wires

Dash Turn Indicator Wires

Dash Turn Indicator Wires

Dash Turn Indicator Wires

I temporarily install the ignition switch so I can test the wiring system. The terminals on the back of the ignition are numbered and the wires go on the terminals as follows.

Terminal#   Wire Color
(30)             RED
(15)             GREEN
(54)             GREENViolet
(58)             GREY-Black

I’ll install the ignition switch and turn signal indicator wires later when I install the handlebars and the dash.

Horn

I install the horn on the bracket on the front frame cross tube. Unlike most BMW horns that install hanging down, the R80ST horn mounts at 90 degrees to frame bracket. The horn mounts with two thin steel straps on the back of the horn. These are important for making the horn vibrate so it is loud.
The BROWNWhite and GREEN-Black wires attach to the terminals on the back of the horn.

Horn & Hardware

Horn & Hardware

Horn Has Two Thin Straps-Important To Make The Horn Loud

Horn Has Two Thin Straps-Important To Make The Horn Loud

Horn Bracket Mounts 90 Degrees In Frame Bracket

Horn Bracket Mounts 90 Degrees In Frame Bracket

Horn Bracket Mounts 90 Degrees In Frame Bracket

Horn Bracket Mounts 90 Degrees In Frame Bracket

Horn Wires Installed On Terminals With Rubber Boots

Horn Wires Installed On Terminals With Rubber Boots

Clutch And Front Brake Light Switches

I’ll install these with their sub-harnesses when I install the handlebars.

Handlebar Lever Clutch Switch & Sub-Harness

Handlebar Lever Clutch Switch & Sub-Harness

Front Brake Brake Light Handlebar Switch & Sub-Harness

Front Brake Brake Light Handlebar Switch & Sub-Harness

Ignition Coil

The ignition coil mounts on the right side of a bracket welded to the frame near the front of the bike. It attaches with two Allen head bolts with wave washers. I attach the GREENBlue pair of wires to the coil terminal near the frame and the pair of BLACK wires on the outside terminal.

Coil Frame Bracket

Coil Frame Bracket

Coil Hardware Detail

Coil Hardware Detail

Coil Mounted On Frame Bracket

Coil Mounted On Frame Bracket

Coil Power Terminals Above Red Spark Plug Wire Terminals

Coil Power Terminals Above Red Spark Plug Wire Terminals

Coil Power: LEFT GREEN-Blue; RIGHT BLACK

Coil Power: LEFT GREENBlue; RIGHT BLACK

Handlebar Multifunction Switch Sockets

The handlebar multifunction switch cables have a socket on the end that attach to sockets on the main wiring harness. The left handlebar multifunction switch cable has a RED and BLACK socket and the right cable has a WHITE socket which match the same color sockets on the main wiring harness. The main wiring harness sockets snap into holes in a bracket welded to the frame just above the coil. The front of the sockets has a ridge on the top and bottom of the socket and the rear of the socket has fingers on the top and bottom.

Handlebar Multi-Function Switch Sockets Mounted In Frame Bracket-Left, BLACK & RED Is On Top, Right, White Is On Bottom

Handlebar Multi-Function Switch Sockets Mounted In Frame Bracket-Left, BLACK & RED Is On Top, Right, White Is On Bottom

Handlebar Multi-Function Control Sockets Mounted In Frame Bracket (Left On Top)

Handlebar Multi-Function Control Sockets Mounted In Frame Bracket (Left On Top)

Ignition Control Unit

The ignition control unit (ICU) mounts on a heat sink which attaches to a bracket on the frame. The ICU has a metal base and two small plastic pins that fit in holes on the front of the heat sink. Two screws attach the ICU using the holes at the edges and screw into threaded holes in the heat sink.

Heat Sink, Hardware & Ignition Control Unit

Heat Sink, Hardware & Ignition Control Unit

Plastic Pins On Bottom Of Ignition Control Unit Fit In Holes On Heat Sink

Plastic Pins On Bottom Of Ignition Control Unit Fit In Holes On Heat Sink

Ignition Control Unit Mounting Hardware Detail

Ignition Control Unit Mounting Hardware Detail

Orientation of Ignition Control Unit On Heat Sink

Orientation of Ignition Control Unit On Heat Sink

Before I mount the ICU on the heat sink, I apply a heat transfer paste to the metal pad on the bottom of the ICU. This is important as the heat sink paste ensures that the ICU does not overheat. If it overheats, the ICU will stop working.

Applying Heat Transfer Paste To Metal Plate On The Back Of Ignition Control Unit

Applying Heat Transfer Paste To Metal Plate On The Back Of Ignition Control Unit

Attaching Ignition Control Unit To Heat Sink

Attaching Ignition Control Unit To Heat Sink

The heat sink attaches to the frame with two Allen bolts with wave washers.

Ignition Control Unit & Heat Sink Mounted To Frame Bracket

Ignition Control Unit & Heat Sink Mounted To Frame Bracket

Ignition Control Unit Mounted

Ignition Control Unit Mounted

Install Electronic Ignition Plug From Engine On Bottom Of Ignition Control Unit

Install Electronic Ignition Plug From Engine On Bottom Of Ignition Control Unit

The cable from the ignition trigger inside the engine has a wide connector that attaches to the bottom of the ICU and is secured by a wire bale. There is a white connector attached to wires (BLACK, BROWN, GREEN) from inside the engine that connects to a white socket on the main wiring harness with BLACK, BROWN, GREENBlue wires.

White Connector With BLACK, BROWN, GREEN Wires From Engine Connect To White Connector With BLACK, BROWN & GREEN-Blue Wires On Main Wiring Harness

White Connector With BLACK, BROWN, GREEN Wires From Engine Connect To White Connector With BLACK, BROWN & GREENBlue Wires On Main Wiring Harness

White Socket With BLACK and BLUE Wires

There is a white socket on the main wiring harness with a BLACK and a BLUE wire that attaches to a white socket with BLACK and BLUE wires that come from inside the engine. I orient the sockets to they are on the left side.

BLUE & BLACK Wires In White Connector Coming From Engine

BLUE & BLACK Wires In White Connector Coming From Engine

Voltage Regulator And Frame Ground

The voltage regulator is an Enduralast unit from Euro MotoElectrics. It is solid state and the charging voltage can be adjusted.

Euro Motoelectrics Solid State, Adjustable Voltage Regulator

Euro Motoelectrics Solid State, Adjustable Voltage Regulator

Euro Motoelectrics Solid State, Adjustable Voltage Regulator (Square Blue Box On Left Is Voltage Adjustor)

Euro Motoelectrics Solid State, Adjustable Voltage Regulator (Square Blue Box On Left Is Voltage Adjustor)

The voltage regulator attaches to a frame bracket to the rear of the ignition control unit. The cluster of BROWN frame ground wires with the ring terminal attach the voltage regulator mounting bolt nearest the frame.

Bracket For Voltage Regulator Is Behind Ignition Control Unit

Bracket For Voltage Regulator Is Behind Ignition Control Unit

Frame Ground With BROWN Wires Attached To Voltage Regulator Mounting Bolt

Frame Ground With BROWN Wires Attached To Voltage Regulator Mounting Bolt

The triangular black connector from the engine with the BLACK, BROWN & BLUE wires plugs into the bottom of the voltage regulator.

Triangular Plug With BLACK, BROWN & BLUE Wires Install In Bottom Of Voltage Regulator

Triangular Plug With BLACK, BROWN & BLUE Wires Install In Bottom Of Voltage Regulator

Headlight & Starter Relays

The headlight and starter relay sockets mount in a frame bracket to the rear of the voltage regulator bracket. The sockets have a tab and are secured with a screw that has a large flat washer. The relays plug into the top of the socket. The sockets install from the bottom of the bracket and are held in place with two ears on the sides of the socket. I label the top of the relays so I can easily tell which is the headlight and the starter relay.

Starter Relay Socket And Hardware

Starter Relay Socket And Hardware

Mounting Starter Relay Socket On Frame Bracket

Mounting Starter Relay Socket On Frame Bracket

Headlight (Left-HL) & Starter (Right-ST ) Relays Plugged Into Brackets

Headlight (Left-HL) & Starter (Right-ST ) Relays Plugged Into Brackets

Turn Signal Relay

The turn signal relay mounts on the same frame bracket as the headlight and starter relays. But, it mounts underneath the bracket. The original turn signal socket mounted in the screw hole next to the frame and the relay pointed toward the rear. The new wiring harness socket is longer so it won’t mount the same. I mount it in the outside screw hole and point the relay perpendicular to the frame. This shouldn’t make any difference.

Mounting Turn Signal Relay Socket On Bottom Of Frame Bracket

Mounting Turn Signal Relay Socket On Bottom Of Frame Bracket

Turn Signal Relay Socket Mounting Detail

Turn Signal Relay Socket Mounting Detail

Turn Signal Relay Installed Perpendicular To The Frame

Turn Signal Relay Installed Perpendicular To The Frame

Special Equipment Socket

This socket is painted blue. It mounts similarly to the way the handlebar multi-function switch sockets mount. However, It mounts from the bottom of the bracket. There was a black plastic cover that protected the pins from rain on the original socket and I install it on the new socket.

Blue Special Equipment Connector

Blue Special Equipment Connector

Special Equipment Connector Installed

Special Equipment Connector Installed

Cover For Special Equipment Connector

Cover For Special Equipment Connector

Special Equipment Connector With Cover On Top To Protect Pins From Rain

Special Equipment Connector With Cover On Top To Protect Pins From Rain

Fuse Box

The fuse box has two 8 amp fuses inside. It mounts at the end of the frame spine tube. There is a bracket that attaches to the fuse box. A hose clamp attaches the fuse box bracket to the bottom of the frame spine tube.

Fuse Box Has Two 8 Amp Fuses Inside. Mounting Bracket Screws To Back Of The Box And Is Secured To Frame Tube With Hose Clamp.

Fuse Box Has Two 8 Amp Fuses Inside. Mounting Bracket Screws To Back Of The Box And Is Secured To Frame Tube With Hose Clamp.

Fuse Box Cover Attaches With Thumb Screw In The Middle

Fuse Box Cover Attaches With Thumb Screw In The Middle

Fuse Box Mounted On Spine Tube With Hose Clamp

Fuse Box Mounted On Spine Tube With Hose Clamp

Fuse Box Mounted On Spine Tube With Hose Clamp

Fuse Box Mounted On Spine Tube With Hose Clamp

On the back of the fuse box are terminals on each side. I install the GREEN and GREY wires on the left side terminals. I install the GREEN-Black wire opposite the GREEN and the GREY-Black wire opposite the GREY wire. The GREEN and BLACK wires carry power from the battery and the black striped wires indicate that these carry power after the fuse.

GREEN & GREY Wires From Battery Before Fuses Go On One Side Of Fuse Box

GREEN & GREY Wires From Battery Before Fuses Go On One Side Of Fuse Box

GREEN-Black and GREY-Black Wires Go On Opposite Side Of Fuse Box And Are After The Fuses

GREEN-Black and GREY-Black Wires Go On Opposite Side Of Fuse Box And Are After The Fuses

Oil Pressure Switch & Transmission Neutral Switch

The oil pressure switch screws into a tapped hole on the lower left side of the engine block. The transmission neutral switch installs in the transmission, but I’m still rebuilding the transmission.

Oil Pressure Switch Hole In Lower Left Side Of Engine Block

Oil Pressure Switch Hole In Lower Left Side Of Engine Block

Oil Pressure Switch With Flat Washer

Oil Pressure Switch With Flat Washer

Oil Pressure Switch Installed

Oil Pressure Switch Installed

The transmission sub-harness has a BROWNGreen wire that goes on the terminal of the oil pressure switch. The BROWN-Black and BROWN wires go on the terminals of the transmission neutral switch. The BROWN wire with the ring terminal attaches to the transmission under the left bottom transmission mounting bolt. I’ll install the neutral switch wires when I install the transmission.

Transmission Neutral Switch & Oil Pressure Switch Sub-Harness

Transmission Neutral Switch & Oil Pressure Switch Sub-Harness

Transmission Neutral Switch Wires BROWN-Black, BROWN And Ring Terminal Wire

Transmission Neutral Switch Wires BROWN-Black, BROWN And Ring Terminal Wire Connections For Transmission Neutral Switch

Rear Brake Light Switch

The rear brake light switch mounts on a bracket on the lower right of the frame. It is secured with two screws. The wires, GREEN-Black and GREENRed, thread through a rubber cover that protects the switch from water. The wires fit into holes in the switch body and are secured with two set screws. The sub-harness wires connect to a plug on the end of the main wiring harness.

Rear Brake Light Switch Mounts On Frame Tab With Two Screws

Rear Brake Light Switch Mounts On Frame Tab With Two Screws

Rear Brake Light Cover With Wires Inserted

Rear Brake Light Cover With Wires Inserted

Rear Brake Light Switch Wire Installation Detail

Rear Brake Light Switch Wire Installation Detail

Rear Brake Light Rubber Cover Installed

Rear Brake Light Rubber Cover Installed

Rear Brake Light Sub-Harness Connection To Main Wiring Harness Plug

Rear Brake Light Sub-Harness Connection To Main Wiring Harness Plug

Install Rear Sub-Frame

I install the rear subframe so I can install the rear turn signals. It attaches to the frame with four bolts. The top right leg of the rear sub-frame attaches with a bolt that screws into a tapped hole. The other three bolts have washers and nuts. I torque all the bolts to 16 Ft-Lbs.

Rear Sub-Frame Hardware

Rear Sub-Frame Hardware

Torque Sub-Frame Bolts To 16 Ft-Lbs

Torque Sub-Frame Bolts To 16 Ft-Lbs

Rear Sub-Frame Installed

Rear Sub-Frame Installed

Install Rear Turn Signals

The rear turn signal stalks mount to the rear of the sub-frame. There is a hole next to the mounting bolt for the turn signal wires in the rear wiring sub-harness. I attach the rear wiring sub-harness to the plug at the end of the main wiring harness. Then I push the wires through the holes in the turn signal stalks; BLUE-Black wire is right side and BLUERed wire is left side.

Hole For Turn Signal Wires In Rear Turn Signal Stalk

Hole For Turn Signal Wires In Rear Turn Signal Stalk

Hole In Rear Sub-Frame For Mounting Rear Turn Signal Stalk

Hole In Rear Sub-Frame For Mounting Rear Turn Signal Stalk

Rear Turn Signal Stalk Hardware Detail-Bolt Head Faces To Rear

Rear Turn Signal Stalk Hardware Detail-Bolt Head Faces To Rear

Rear Turn Signal Stalk Hardware Detail

Rear Turn Signal Stalk Hardware Detail

Insert Turn Signal Wires Through Hole Next To Mounting Bolt

Insert Turn Signal Wires Through Hole Next To Mounting Bolt

Rear Turn Signal Wires

Rear Turn Signal Wires

The rear turn signal housing mounts to the stalk and the wires attach to the turn signal reflector the same as on the front turn signals. The lens has the same “TOP” mark as on the front.

Rear Turn Signal Housing Mounts Same Way As Front Housing

Rear Turn Signal Housing Mounts Same Way As Front Housing

Install Rear Tail Light

The rear tail light housing mounts on the rear fender, but that is still at the painters, so I can’t mount the rear tail light. But I wire it up so I can test it.

The rear bulb has two filaments, one for the park/running light and the other for the brake light. On the back of the reflector, the terminals are labeled (54) for the brake light and (58) for the park/running light. The brake light wire is GREENRed and the park/running light wire is GREY-Black. The BROWN ground wire attaches to the strap on the outside of the bulb.

Terminal (54) Is Brake Light Terminal

Terminal (54) Is Brake Light Terminal

Terminal (58) Is Parking Light Terminal

Terminal (58) Is Parking Light Terminal

Rear Light Wiring Installed On Back Of Reflector

Rear Light Wiring Installed On Back Of Reflector

Rear Tail Light Assembly

Rear Tail Light Assembly

Install Battery Box And Battery

The battery box mounts in the frame on four rubber bushings with studs that act as vibration dampers. Each stud has a nut and wave washer. Two of the vibration dampers mount on a bracket on the lower frame cross tube and the other two mount on the vertical frame tubes.

Battery Box & Mounting Hardware

Battery Box & Mounting Hardware

Battery Box Vibration Dampers Installed

Battery Box Vibration Dampers Installed

Battery Box Vibration Dampers Installed

Battery Box Vibration Dampers Installed

The battery mounts in the battery box with two rubber straps that attach to brackets on the bottom rear and top front of the battery box.

Battery Straps

Battery Straps

Battery Straps Installed

Battery Straps Installed

Battery Straps Installed

Battery Straps Installed

I attach the cable from the starter motor and the wire from the main wiring harness, both of which have RED markings on the ends, to the battery (+) terminal. I install the battery ground cable to the battery (-) terminal using the ring terminal with the 90 degree bend. The other end of the ground cable attaches to the transmission using the speedometer drive bolt, but I haven’t installed the transmission yet, so I use a jumper wire to attach the end of the ground cable to the transmission stud on the rear of the engine block. I also attach the ring terminal with the BROWN wire from the neutral and oil pressure switch sub-harness to the the transmission mounting stud so I can test the neutral switch.

Wiring Harness RED Wire Goes To Battery (+) Terminal

Wiring Harness RED Wires Go To Battery (+) Terminal

Battery (+) Terminal With Starter Motor & Wiring Harness RED Connections

Battery (+) Terminal With Starter Motor & Wiring Harness RED Connections

Battery Ground (-) Jumper Wire Attached To Transmission Stud In Engine Block

Battery Ground (-) Jumper Wire Attached To Transmission Stud In Engine Block

Battery Ground (-) Jumper & Oil Pressure-Neutral Switch Ground On Transmission Stud

Battery Ground (-) Jumper & Oil Pressure-Neutral Switch Ground On Transmission Stud

Test Electrical System

I temporarily connect the ignition switch so I can test the electrical system. I test the PARK and ON positions of the ignition switch and the kill switch. I test the horn, high beam and high beam flasher. I verify that the indicator bulbs in the tachometer work. I test the brake lights.  Everything works. 🙂

Ignition Temporarily Installed

Ignition Temporarily Installed

Here is how the bike looks with the electrical system installed.

Electrical Components Installed Along Frame Spine Tube

Electrical Components Installed Along Frame Spine Tube

Electrical Components Installed Along Frame Spine Tube

Electrical Components Installed Along Frame Spine Tube

Revisions

2022-12-17  Add explanation of getting headlight relay to work for wiring bench test.

8 thoughts on “61 BMW 1983 R80ST Install Electrical System

  1. This is the best and most well-founded site for restoring old BMWs that I know of. I can’t believe how detailed you document everything. Thanks for your hard work and effort! Greetings from Germany, Lupo

  2. Brook,
    I’ve been following this rebuild since it’s beginning, as I’ve recently acquired and been getting acquainted with my first airhead, an ’83 ST. It’s been really informative and serves as a virtual tear down of my bike. Thank you for the thorough work and documentation.

    What exactly is the “special equipment” connector for? The first time I pulled off the tank to take a peek, I was surprised to find an empty connector on the main harness. I wish I had the original cover like you do.
    Best,
    Rey

    • Rey,

      Based on the wire colors, it looks like it could be used for auxiliary lighting. That said, I’m not positive what BMW had in mind.

      Best.
      Brook.

  3. Hi Brook,
    I love your builds, so much useful information. I see you used a stock taillight. I have a new spare LED one from the Beemershop. If you are interested in using I would happily donate. Please let me know.
    Gregg

  4. Brook,
    Happy Holidays!
    Regarding the rear tail light you used, did you have to drill a hole and install the rubber grommet and wiring through the housing, or was it all wired together already? Both the EME and BMW Fiche show a housing without the hole on the left side light, so I’m wondering if I got a new tail light housing, should I expect to drill the side of the housing and fit all the connectors through the grommet? Or worse, remove and replace the spade connectors if they don’t fit through the grommet?
    Thank you!
    Rey
    -PS my Christmas wish is to win your ST. 🙂

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