By Tusker, Wed Dec 10, 2008

Original thread: Euro Headlight wash/wipe troubleshooting

Problem: My Euro headlight wash/wipe doesn't work.

Cause: Could be a number of things. The common failures are the headlight wash/wipe control unit and the headlight wiper motors.

How to fix: Working headlight wash/wipe systems are the exception. They are not well documented, so they often go unfixed and the moving parts get worse. This is a troubleshooting guide. Fixing generally means replacing failed parts.

If you have not done electrical troubleshooting before, read the Bentley for general tips. The tests below were checked; not every one was needed on the author's car.

Rule out the simple things

Operator error. Ignition on, headlights on, press the button on the end of the right-hand column stalk. That is the service wash.

The service wash squirts a short burst of undiluted wash from the small reservoir nearest the cabin, then a longer squirt of diluted wash from the larger reservoir next to it, with the windscreen wipers. Then it squirts diluted wash on the headlights and runs the headlight wipers.

The headlight wash/wipe only works with the headlights on. Headlights off, you only get windscreen wash. Some cars fire the headlight cycle every third press. Try five cycles with about 10 seconds between them before you assume it is broken.

Fuses. The wash/wipe system shares a fuse with the horns. If the horn works, it is not the fuse.

Approach

After the obvious, split the system into three:

1. Downstream of the headlight wash/wipe control unit — motors and the wiring from the control unit to the motors
2. The control unit itself
3. Upstream of the control unit — service-wash button, wash-interval control unit, and associated wiring

Study the wiring diagram near the end of this page first.

Downstream of the control unit

The control unit is fastened to the washer-fluid container in the left front of the engine bay.

Headlight wash/wipe control unit on the washer bottle.

Disconnect the wiring connector. Testing is easier if you unscrew the unit from the bottle. The connector diagram on the unit shows terminals on the unit itself — that is the mirror image of the wires when you look down on the connector.

Connector terminals, looking down on the harness side.

To run the motors: with the usual care, connect a fused lead from battery + to terminal 53 on the connector. Then touch terminal 53a with another fused lead from battery + for 2–3 seconds only. That should run the headlight washer pump and cycle the headlight wipers for about 30 seconds, then shut off.

If that works, skip to the upstream checks. If not, test the motors and pump.

To operate the system manually forever, wire it this way with a toggle switch in the 53a lead.

Motors and pump

1. Remove the covers over the headlights in the engine bay.
2. Disconnect all connectors to the headlights and headlight wiper motors.
3. Remove the wiper blades, front grilles, and headlights. You can leave each motor on the headlight frame for testing.

The right-hand motor (facing the car) has 3 leads (R, BL, BR). The left has 4 (R, BL, BR, and an extra BL).

• Red — 12 V momentary
• Black — 12 V constant
• Brown — ground
• Blue on the left motor — output signal to the washer pump

To test a motor: fused lead from battery + to the black lead, ground the brown. Touch the red lead with another fused + for 2–3 seconds only. The motor should cycle about 30 seconds and shut off. The connector is awkward; a scrap of matching loom helps you avoid shorting pins.

To test the washer-pump output on the left-hand motor (the one with the extra blue lead): meter between the blue lead and ground, then repeat the motor test. Voltage should rise from 0 V for a second or two.

A dead motor is easiest to replace (part #s 61631369105 / 61631369106).

To test any pump: disconnect it, + to one terminal, ground the other. It should run. The headlight washer pump is the same part as the intensive-wash pump and the windscreen washer pump (part # 61661368589).

If motors and pump work, the fault is wiring. Clean connectors and check for breaks against the diagram. Reassemble and repeat the 53 / 53a test at the control-unit connector. Then try the service-wash button. If that still fails, there is another fault.

The control unit

Without a known-good unit to swap, simulate the feed from the wash/wipe interval control unit (ignition and headlights on) by grounding the connector with the BR/GY wire on the intensive pump. That should trigger a headlight wash/wipe cycle.

If not:

1. Confirm the intensive-wash pump works
2. Check wiring and clean connectors between the pump and the control unit

If that still fails, the control unit is likely dead. Replacing it is the practical option. Part # 61311367391. Dealer price was about UK£60 when this was written; good used units were about UK£10 and often untested.

Upstream of the control unit

Service-wash switch. Remove the lower steering-column cover and unplug the stalk connector. Pressing the button should connect TS (BR/BL) and PS (BR/GY). Resistance should drop to zero. You do not need to pull the stalk or the wheel to test. If it fails, replace it (part # 61311369932 from 09/85).

Wash/wipe interval control unit. Big black box at the top of the fuse box. If the windscreen wipers work, this is unlikely — but not impossible. The only practical test is swapping a known-good unit. A failure here would usually take out the windscreen washers too.

If every test above passes and it still does not work, walk through it again.

How the system is supposed to work

Euro headlight wash/wipe wiring.

References are to that diagram. This is a working model of the control units, not a factory description of what is inside them.

• Terminal PS on the service-wash button is connected to the intensive-cleaning-fluid pump (7) and goes to ground via TS to run it.
• That ground via TS is through the wash/wipe interval control unit (16). A timer there holds the earth on PS long enough to run the intensive pump.
• Current through the intensive pump triggers the headlight-cleaner control unit (1), which then:
  1. Follows the intensive wash by switching on screen wash for a timed interval (earthing 85)
  2. Switches on the headlight wipers
  3. Which triggers the headlight wash

Related links

E24 threads with similar electrics (different mechanisms): bigcoupe t=2107, t=2247.

MyE28 threads: t=3778, t=41268, t=10370, t=12596, t=13179.

US ETM wiper/washer (no headlight wash/wipe):

ETM wiper/washer and heater washer jets.