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 The original online guide to the Volkswagen Cabriolet & Rabbit Convertible!

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General Info






Troubleshooting






DIY Guides & Tips




Electrical System


Last update:

November 1, 2014


Notes



Quick link: Relay/Fuse Panel Diagrams



Fuse & Relay Panel

The Bentley Service Manual has numerous errors in its list for relays and fuses. Most of those errors have been corrected here! However, it's wise to verify your relays using the relay part numbers listed below, especially for the 1980-1982 cars.

  

The fuse/relay panel is located under the dash, driver's side, behind the kneebar.  

  • 1980-1982 fuse/relay panel part number: 171941821C
  • 1983-1993 fuse/relay panel part number: 171941821D


IMPORTANT NOTES:

  • Fuse amperage: Green = 30; Yellow = 20; Blue = 15; Red = 10.
  • 1980-1982 Cabriolets use ceramic fuses; their amperage is listed on the diagram.  
  • 1980-1982 fuel pump relay: Originally installed in position L; due to a recall, the relay should have been moved to position 1 with a wiring loom bridge to position L.
  • If your car has factory-installed heated seats, the relays for this option are under each front seat.
  • If your car has a factory-installed 2-stage after-run cooling fan system ('88+), the relay for this fan is mounted to the left front fender.
  • If your car has factory-installed power windows, there is a control unit beneath the dash on the passenger side.
  • If your car has a factory-installed power top, there is a covered thermo-fuse above the relay panel.
  • If your car has factory- or dealer-installed daytime running lights, there is most likely a relay attached to the top of the panel (not shown in the diagrams).
  • ALL 1983-1993 Cabriolets are CE1










Relay Part Numbers




































Ground Locations
























Wires

Warm wires

Warm-to-the-touch wires are not at all unusual in these cars, due, in part, to the way they were wired at the factory.


However, wires that become so warm or hot that they melt their insulation and/or smoke are cause for concern.  An overly warm wire is indicative of a circuit with high resistance.  This high resistance can be caused by various issues: bad ground connections, poor wire connections, faulty switch, faulty relay, etc.



Wiring Diagrams

Wiring diagrams can be found in the Bentley Service Manual as well as the Haynes Repair Manual.  NOTE: Those with 1986 Cabriolets should follow both the 1986 and the 1987 Bentley main wiring diagrams; much, but not all, of the wiring in a 1986 resembles the 1987 diagrams and the latter diagrams are easier to read.


Voltage Drop

Voltage drop is a common malady on Cabriolets due to a poorly designed electrical system. Voltage drop can be witnessed on the VDO volt gauge with the engine running: When turning on the headlights, for instance, the volts will drop from 14 down to 12 (the drop is actually more severe when reading the voltage at the battery, then at the headlight; this is because the volt gauge is not 100% accurate); the volt gauge needle will also bounce in rhythm with the turn indicators. If the charging system is in good working order and all ground wires/connections are in good shape, this is nothing to really worry about.  However, to combat voltage drop (and to increase headlight output), install headlight relays, clean all ground contacts and replace ground cables. 


Voltage readings (using a DVOM at the battery, not the in-car VDO gauge):

Key-off battery voltage should be 12.6V with a surface charge; 12.3V without a surface charge.

Charging voltage should be 12.8V - 14.7V.


Connecting the OBD Diagnostic Tool

Under the shift boot, towards the front.


NOTE: Only Cabriolets equipped with Digifant I engines have the OBD I diagnostic port; furthermore, an OBD II diagnostic tool cannot be used to pull fault codes from an OBD I system unless it has an adapter!  


Power Windows

Power Windows Don't Work (under construction)

Step 1

Check fuse #17, and the fuse in relay position 17.  Fuses okay? Yes: Proceed to step 2.  No: Replace blown fuse(s).


Step 2

Check for voltage at the power window control unit (located beneath the dash, passenger side; key to battery-on position).  Is there voltage?  Yes: Proceed to step 3.  No: Remove the control unit and check for broken wires, broken internal connections, melted wires/connectors, water.  If there is water intrusion: A) dry the control unit thoroughly; B) reseal the air plenum in the rain tray.  If the control unit is still unresponsive or has melted wires, you'll need to buy a new/used one (part #191959875); and make sure the fuses are good and of proper amperage.


Step 3

Check for voltage at each window switch.  Is there voltage?  Yes:  No:


Step 4


Please refer to this thread and/or this thread and/or this thread on VWvortex for additional info.


Lights

Reverse Lights Do Not Work

If the fuse/relay and bulbs are okay, replace the reverse (back-up) light switch located on top of the transmission (on automatics, the switch is connected to/near the shift lever).


To test the reverse light switch: Disconnect the electrical plug, jump the black and black/blue wire terminals, turn the ignition switch to the battery-on position. If the lights turn on, the switch is faulty.


Headlight Types


Headlight Relays  

Whether you are upgrading your headlights or not, it is a very wise idea to relay the headlights.  The stock headlight wiring uses paltry 16 gauge wires, uses the headlight switch as a power source, and contains lengthy wire runs, all of which cause resistance and, ultimately, voltage drop at the headlights thereby reducing each lamp's luminosity.  Adding relays powers the headlights directly from the battery/alternator, will reduce voltage drop in the electrical system, will extend the life of the alternator, headlight switch and ignition switch, will increase the light output giving you whiter & brighter light, and will reduce the chances of the headlight switch overheating.  Click here for a DIY guide for relaying your headlights.  If you'd rather not do it yourself, a complete relay wiring harness is available for approximately $90 at Concept1 , or for $35 at 4Crawler or $30 from LMCTruck (part #47-3660; requires splicing if you have the dual-round grille).  


A standard Halogen sealed-beam headlamp produces 100% of its light output at 12.8 volts (or 13.2 volts in Europe) or above.  Take a voltage reading at one of your headlights.  What does your meter read?  My meter read 10.86 volts at each lamp, lo-beam.  Using voltage drop figures found on the Web, at 10.86 volts, each of those headlamps was producing less than 53% of their possible light output.  After adding relays to the headlight circuit, each headlight's voltage jumped up to 13.36 volts, which means the lamps are now producing 100% of their possible light output.


Further information regarding headlight wiring, voltage drop, adding relays, etc. can be found at Daniel Stern Lighting.



Headlight Switches

Three different headlight switch types were used in 1981+ Cabriolets.  If you're replacing the switch, use the information below to ensure you're buying the correct one!  For example, AutohausAZ lists the 321-K switch for a 1990 Cabriolet, which is the wrong one!  (Click on the linked part numbers to see examples.)

Part #321941531G

  • 1981 through 1986
  • Same switch as below, but with old light symbol (i.e. the two switches are interchangeable)

Part #321941531K

  • 1987 to mid-1989 (up to VIN K-009000)
  • Same switch as above, but with modern light symbol (i.e. the two switches are interchangeable)

Part #323941531G

  • Mid-1989 through 1993 (from VIN K-009001)

Part #323941531H

  • Canadian Cabriolets with Daytime Running Lights (from VIN K-011306)


Headlight switch terminal translations (thanks to Andrew K.):

TFL = Daytime Running Lights (DRLs)

NSL = Rear Fog Lamp

SRA = Headlight Cleaning System


City Lights

If you are installing city lights on a North American Cabriolet, wire the lights to the stock wiring based on how you want the lights to be used.


Stock wiring in the car:

Black = turn signal

Gray = parking/running light

Brown = ground


If you're installing Euro bumper lights that include city lights, you'll need to splice the two ground wires together prior to wiring them to the car's brown ground wires.  



Disabling Day-time Running Lights

Pull the headlight switch and place electrical tape over the TFL pin; reinstall switch.  If your switch does not have a wire going to the TFL pin, or is without a TFL pin: Your car may have hard-wired day-time running lights (DRLs) from the factory.  To disable DRLs on these cars (thanks to Rob for the info): Locate the yellow 20-gauge wire on the back of the headlight switch; either push/pull it out of the harness connector, or cut it and cap/tape it off.  You can also disconnect the same yellow 20-gauge wire from the A-21 pin on the back of the relay panel.



Installing LEDs

Want to brighten up your lights, or change their color, or reduce the power drain?  Replace the original incandescent bulbs with LEDs.  LEDs have come a long way in the last several years.  Rather than buying LEDs and the appropriate resistors, you can now buy LEDs that include resistors for a plug-and-play application in most instances. Download the DIY Guide for a how-to.  Click here for a breakdown of what you need.


Engine Sensors, Senders & Switches



Windshield Wipers

Adding variable wiper option

Look for relay #357955531 or #3B0955531 (has a printed 99. on it in OEM form) found in the following vehicles:


1995-1997 Cabrio & Eurovan

1992-1994 Corrado SLC

1993-1996 Golf/Jetta 2.0L

1990-1997 Passat


Or, order a new one from German Auto Parts. You can also peruse eBay for the OEM relay or the KAE version.  It is a plug and play swap; replace your existing relay with the new one.


To program the variable feature: "Pull the lever into the intermittent position, and, as the wiper does it's sweep, click back into the stop position, if you want a 3 second gap, then wait 3 seconds, and click back into the intermittent position. Bam, you just programmed a 3 second timing."


If ^that doesn't work: "Pull the stalk towards you to (for windshield washers) while the wipers are set to intermittent. This initiates the timer. If left alone at this point it will default to the 20s interval. Pull the stalk towards you again and it will set the timer to that interval, anywhere from 5 to 20 seconds."


Rev Limiters

The CIS Cabriolets have a rev limiter built into the fuel pump relay.  When the rpm reaches the built-in limit, the fuel pump relay shuts off the fuel pumps.  This is a safety feature; however, the relay can be replaced with a "no-rev" or "hi-rev" version so that the cut-off point is eliminated or increased to approximately 7500 rpm.  Digifant Cabriolets have a rev limiter built into the ECU and cannot be altered.


Relay Part Numbers and Replacement Equivalents (CIS only) - see fuel system page for additional info

__Years             VW/Altrom                 Kräcker / KAE ______      Approx Rev Limit

1980-1982        321906059C                  3.300.100                            6200

1983-1985        321906059D            NLA; replacement is F                 6500

1986-1989        321906059E            NLA; replacement is F                 6500

1983-1993        321906059F            24.1400.20 / 3.300.210               6500**

1986-1993*      321906059G                   3.300.220                           7500**

1983-1984 GTI   433906059                    3.300.300                           none

*Europe JH/DX/KT engines


**Unverified; many North American sources say that the F relay is a "hi-rev" version with a 7500 rpm limit.  If anyone has hard proof of this, please let me know.  The G relay's limit is unknown; 7500 limit is a presumption given that it was used in European Golf I GTIs (i.e. those with DX engines).


The above table is for reference only and may not be 100% accurate as the information is based on the VW parts catalog.  For example, the parts catalog shows that my '86 should have a G relay when, in fact, it has an E relay (original, never been replaced).


Panel Diagrams

1980 - 1982

CIS

1983 - 1984

CIS

1985 - 1987

CIS

July 1987 - 1989*

CIS

1990 - 1993

Digifant

Diagram

Actual Panel

Diagram

Actual Panel

Diagram

Actual Panel

Diagram

Actual Panel

Diagram

Actual Panel

Click here for a manual supplement containing relay & fuse diagrams, relay panel pin-out schematics, and a guide to reading current flow wiring diagrams.

* Up to 1993 outside North America.

Relay

Years

Original Part Number

Current Part Number

Air Conditioning

1980 - 1982

1983 - 1993

161959141

171959141A

161959141

171959141A

Cold-start Enrichment (CIS)

1988+

141951253B

141951253B

Coolant Low-level Warning Control Unit

1988+

191919376A

191919376A

Cooling Fan Time Control Unit (Digifant)

1990+

191955532A

191955532A

Cooling Fan After-run Control Unit

1988+

171919505A

171919505A or 141951253B

Daytime Running Lights

(depends on locale)

701919505

701919505

Digifant Control Unit

1990 - 1993

141951253B

141951253B

Fog Lamp (Europe)

all

141951253B

141951253B

Fuel Injection (Lambda) Power Supply (CIS)

1980+

171906381

171906381 or 7M0951253

Fuel Pump (CIS)

1980 - 1982

321906059C

321906059C

Fuel Pump (CIS)

1983 - 1985

1986 - 1989

1986-1993 (Europe)

321906059D

321906059E

321906059G

321906059F (replaces D and E)

321906059G (replaces D, E, G)

Fuel Pump (Digifant)

1990 - 1993

191906383C

191906383C

Headlight Washers (Europe)

1979 - 1987

701955200

701955200

Heated Seats

(depends on locale)

443919533A

443919533A

Horns

1980+

141951253B

141951253B

Hot-start Pulse Relay (CIS)

1980+

813906064

813906064

Idle Stabilizer Control Unit (CIS)

1984+

811905343

811905343

Intermittent Wipers

1980 - 1989

1990 - 1993

321955531A

191955531

321955531A or 191955531

Load Reduction

(aka "X relay")

1980 - 1982

1983 - 1987

1988+

171937503

171951253A

7M0951253A

171937503

171951253A

7M0951253A

Power Top Circuit Breaker

443937105

443937105

443937105

Power Window Control Unit

191959875

191959875

191959875

Power Windows (Europe)

141951253B

141951253B

141951253B

Seat Belt Warning

(interchangeable between years)

1980 - 1984

1985+

171919433 (buzzer)

321919433B (chime)

171919433 (buzzer)

1H0919433A (chime)

Starter Inhibitor/Interlock (A/T)

1990+

191927181 & 191919185

191927181 & 191919185

Turn Signals & Emergency Flasher

1980 - 1982

1983+

111953227D

1H0953227

1H0953227

Up-shift Indicator Control Unit

1981 - 1987

171919091C

171919091C

1980 - 1986

1987 - 1989

1990 - 1993

Main ground cables/straps:

  • Battery to the left frame rail; frame rail to the transmission (part #171971235F)
  • Valve cover to the ignition coil bracket (part #357971537; 360mm)
  • Fender to hood (part #533971537; for radio)
  • A/C compressor to battery (or engine block)
  • Ignition Control Unit to battery


Ground locations:

  • Fuse/relay panel
  • Steering column
  • Cold-start valve (CIS only)
  • Trunk, rear left and right
  • Dash wiring harness
  • Ignition distributor


Main ground cables/straps:

  • Battery to the left frame rail; frame rail to the transmission (part #171971235F)
  • Valve cover to the ignition coil bracket (part #357971537; 360mm)
  • Fender to hood (part #533971537; for radio)
  • A/C compressor to engine block (or alternator)
  • Ignition Control Unit to battery


Ground locations:

  • Fuse/relay panel
  • Steering column
  • Cold-start valve (CIS only)
  • Trunk, rear left and right
  • Dash wiring harness
  • Engine bay, front left and right ('88+)


Main ground cables/straps:

  • Battery to the left frame rail; frame rail to the transmission (part #155971235B)
  • Valve cover to the ignition coil bracket (part #357971537; 360mm)
  • Fender to hood (part #533971537; for radio)
  • Digifant ECU to firewall
  • A/C compressor to engine block (or alternator)


Ground locations:

  • Fuse/relay panel
  • Instrument cluster wiring harness
  • Steering column
  • Trunk, rear left and right
  • Engine bay, front left and right
  • Horns ('91+)


Please use the Bentley Service Manual wiring diagrams for complete wire routing for your particular car.

Keep your electrical system tip-top by cleaning your electrical connections!

Additional info and Digifant photos can be found here.

Oil System

Part Number

Function

Location

Image

Oil temperature gauge sender

single, white nail-head connector

049919563A

Sends oil temp to gauge

Top of oil filter flange

Image

Oil pressure sensor & gauge sender

0.3 bar

035919561-

Warns, with a flashing light, when oil pressure falls to near zero and sends pressure reading to center console bar gauge

Left side of cylinder head*

Image

Oil pressure sensor

1.8 bar ~ 1 pin, white

056919081E

Warns, with flashing light and buzzer, when oil pressure falls too low at higher (2000+) rpm

Top of oil filter flange*

Image

Cooling System

Part Number

Function

Location

Image

Coolant temp gauge sender  (CIS)

single, black nail-head connector

499919501

Sends coolant temperature to dash gauge and warning system

Top of upper radiator hose flange at cylinder head (1.8L; others are similar)

Image

Coolant temp gauge sender  (Digifant)

black connector

251919501D

Sends coolant temperature to dash gauge and warning system

Coolant flange at cylinder head

Image

Coolant temp sensor  (Digifant)

blue connector

025906041A

Provides an engine temp input to the Digifant control unit that is used to boost fuel delivery to improve cold-running driveability

Coolant flange at cylinder head

Image

Coolant level sensor  (Digifant)

251919372A

Senses level in coolant expansion tank; when the level is too low, the sensor sends a signal to the idiot light in the dash cluster

In coolant expansion tank

Image

Cooling fan thermo switch

95-84°C, 2-pin, single-speed fan

95-84°C/102-91°C, 3-pin, 2-speed fan

191959481B (2-pin)

321959481E (2-pin)

191959481C (3-pin)

Switches the cooling fan on/off

Lower, left corner of radiator

Image

Oxygen sensor thermo switch  (CIS-lambda)

1980-1983

056919369AA (25°C)

Controls operation of OXS system

Note: Original switch is not replaceable; original assembly is NLA. Click link at right for replacement details.

Left side of cylinder head in one of the heater hoses

Image

Oxygen sensor thermo switch  (CIS-lambda)

1984+

035919369D (25°C)

027919369B (45°C)

Controls operation of OXS system

(25°C  is standard; 45°C is for cold climates)

Underside of upper radiator hose flange at cylinder head

Image

Thermostat

056121113D (87°C)

Controls coolant flow

Inside the lower radiator hose flange on water pump housing

Image

Thermo-time switch  (CIS)

brown two-pin connector

043906163A

Controls operation of cold-start valve when engine is cold based on coolant temperature

Top of upper radiator hose flange on cylinder head

Image

Electrical System

Part Number

Function

Location

Image

Reverse light switch & up-shift indicator

manual transmission

171919823A (4-speed)

191919823 (5-speed)

Turns back-up lights on when transmission is put into reverse; disables up-shift system, if installed, when in 5th or reverse gears (note: early 5-speed version is NLA)

On top of transmission bell housing

Image

Reverse light switch

manual transmission (1988+)

020945415A

Turns back-up lights on when transmission is put into reverse

On top of transmission bell housing

Image

Reverse light switch

(aka park-neutral safety switch)

auto transmission

311927147B (to late '90)

155927147 (from late '90)

Turns back-up lights on when transmission is put into reverse; prevents car from starting unless gearshift is in Park or Neutral

Base of shift lever in passenger compartment

Image

Brake light switch

up to chassis E-22076

113945515H (2-pin)

113945515G (3-pin)

Turns the brake lights on any time the brake pedal is pressed; works via brake fluid pressure

In brake master cylinder

Image

Brake light switch

from chassis E-22077

191945515B

Turns the brake lights on any time the brake pedal is pressed; works via electric signal

On brake pedal

Image

Cruise control cut-out switch

manual transmission

811907343B

Turns off cruise control system when clutch pedal is pressed; wired into brake light switch

On clutch pedal

Image

Cold-running enrichment vacuum switch (CIS)

1988-1989

171919825B

Interrupts cold-running enrichment above idle

At front of intake manifold off of the vacuum line going to brake master cylinder

Image

Cooling fan after-run thermo switch

1988+

191919521B (CIS, blue)

191919521D (Digi, yellow)

Controls operation of 2-stage cooling fan after-run system based on engine bay temperature (CIS: 110°C; Digifant: 100°C). Note: Replacements may not be same color; just be sure that the temp rating is the same.

Back side of cylinder head cover between #3 and #4 cylinders

Image

Idle switch  (CIS)

(aka Idle Boost Valve)

026906283B (no A/C)

026906283C (A/C)

Boosts idle speed when rpm's drop to near the stall point; boosts idle speed when A/C compressor engages

Mounted to right strut tower

Image

Idle switch  (Digifant)

(aka Idle Stabilizer Valve)

037906457D

Regulates and stabilizes idle speed

In front of valve cover

Image

Full-throttle switch

(aka enrichment switch)

067133093 (JH to 1990)

067906028 (JH from 1991)

037133093D (2H)

Signals control unit with a signal when the throttle valve is fully open for full-throttle enrichment

On throttle body

Image

Mechanical air flow sensor  (CIS)


Measures intake air flow which then operates the control plunger in the fuel distributor for the proper metering of fuel

Under rubber boot on air filter housing, next to the fuel distributor

Image

Electronic air flow sensor  (Digifant)


Measures intake air flow; signals from this sensor and the ignition distributor are sent to the ECU for the proper metering of fuel

Side of intake air filter housing

Image

Oxygen sensor

035906265B ~ CIS

034906265F ~ CIS '88+

030906265K ~ Digifant II

030906265G ~ Digifant I

Sends signal of combustion efficiency to the ECU for fine-tuning of the air-to-fuel mixture (each fuel injection system processes the signals differently; consult Bentley Manual for further info)

Mounted in exhaust manifold

Image

Up-shift indicator vacuum switch

manual transmission, 1981-1987

171919825B

Relays engine load to the up-shift control unit

Connected to vacuum line to/from distributor

Image

Knock sensor  (Digifant)

054905377A

Detects harmful detonation in combustion chambers; when it does, ignition timing is retarded in small increments until harmful detonation stops

Front of engine block

Image

* Bentley Service Manual has this sensor's location listed incorrectly

Table is for reference only; please verify what your car has before ordering parts.