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Fault. Headlights cut out when using screen washer
PeterM - 5/11/15 at 08:41 AM

When i use the screen washer the headlight main and dip beams cut out! Testing showed that when I disconnect the washer motor earth wire this also causes the headlights to cut out

If anyone has any suggestions about the site and nature of the fault I will be very gratefull to hear them. I suspect it will turn out to be a wash motor or light switch relay circuit earth fault.
Im using a PWS loom made in 1994 with ford sierra 87bg/90bg switchgear.
Thanks for your help
PeterM

britishtrident - 5/11/15 at 09:28 AM

First thing is to check the head light earth's, each head light should have its own ground to the chassis.

It could also be a relay earth fault, are your headlight relay grounds wired correctly or could it be they are grounding through the washer pump.

adithorp - 5/11/15 at 10:20 AM

What BT says. Classic (confusing) symptoms of an earth fault back feeding through another component.

gremlin1234 - 5/11/15 at 12:41 PM

quote:
Originally posted by adithorp
What BT says. Classic (confusing) symptoms of an earth fault back feeding through another component.
I agree classic earth fault, probably the common earth between the headlight relay and the washer pump.
to test, I would run an explicit earth to this point.

PeterM - 5/11/15 at 02:53 PM

Thanks for your prompt replies. It looks as if we all agree on the likely problem areas. when it stops raining I will get upside down in the footwell again and get testing earths!

Fatgadget - 5/11/15 at 04:50 PM

^Shouldnt your headlights earth return be right next to them?