The pop up light conundrum

[Prof]

Ok so here it goes - an issue perhaps similar to the wiper switch problem, but subtly different.
 
The light switch is designed to operate the headlights, and also the retractor motors so that the lights pop up when the headlights are on.  There is an exception to this, which is specific to the European models - but I\'ll cover that later.
 
Also of note, is that the light switch has a button to power the headlight cleaner motor - spraying the headlights when they are up.  It should operate when the lights are raised manually with the service switch, or whenever the headlights are on.
 
The UK cars also have an extra 2 relays, which feed reduced power to the headlights when the light switch is set to sidelights and the ignition is on - the headlights would pop up when this circuit operates.  The control relay for this sits behind the glove box.  If you remove that control relay, the rest of the circuit operates the same as the Jap / US cars, and the headlights only work in the last position.
 
The Problem
 
I can operate the headlights manually with the service switch, but the lights don\'t pop up on their own anymore (they used to).  Also, I can only operate the headlight cleaner when the lights are off or on sidelights setting and the service switch is set to raise the lights.  As soon as I turn on the headlights, the headlight cleaner is disabled.
 
According to the circuit diagram (from Moonwrap), there is a relay within the light switch that is supposed to raise and lower the lights, and it also feeds power to the headlight cleaner switch when the headlights are on.  It\'s obvious that this relay is not switching over properly (but it is switching partially - i.e. the contact with the service switch is broken)  This can be proved by the following experiment:
 
Operate the service switch and raise the lights, then turn the lights on - then operate the service switch to lower the lights - they don\'t lower - if the lights are turned off, the lights go down as expected.  This means the home position for the relay is working.  I\'ve tested the switch off the car, and even tried a 2nd switch - and the switch is working correctly.  It\'s only when it\'s in the car that it fails to work.
 
My questions:
 
1)  Does anyone else have the same problem ?  If so what model car (UK, Import, Cab, Coupe) ?
 
2)  Does anyone know what causes this ?
 
3)  Has anyone fixed it ?

[Prof]

I can\'t believe no one else has issues with their pop up lights :Laugh

[Brett]

My initial thought would be that you have a grounding issue, maybe caused by the accident last year?  Might be worth doing a few continuity checks?

[Prof]

No - grounds are good.  
 
I did a little experiment today - I took the rear fog relay out - as it\'s in parallel with the relay in the switch - and then the manual service switch to raise and lower the lights doesn\'t operate either.
 
It would appear that somewhere between the relays and the light switch the postive feed is broken or very high resistance, and so power is coming through the fog light relay to get to the switch.  It also explains why there isn\'t enough juice once that relay is energised to operate the one in the switch.  In logical terms the solution looks simple - wire a feed into the switch direct - question is how far down the cable is it broken - and is it easy to get to. :3Confused
 
Bloody car electrics

[mpk490p]

have you been using your fog light in the recent bad weather?
i had a issue a few years ago with my electric airel and rear defog becasue the wires ran together down the car the defog got too hot and melted the lot together and burnt the airel out, if you fog relay is next to the headlight one i would check behind (if you can) to see if they have fused together you may be switching your fog on when trying to operate you light etc
just a though but i know your a clever chap and hve proably done all that!

Mark

[Brett]

No - grounds are good.  
 
I did a little experiment today - I took the rear fog relay out - as it\'s in parallel with the relay in the switch - and then the manual service switch to raise and lower the lights doesn\'t operate either.
 
It would appear that somewhere between the relays and the light switch the postive feed is broken or very high resistance, and so power is coming through the fog light relay to get to the switch.  It also explains why there isn\'t enough juice once that relay is energised to operate the one in the switch.  In logical terms the solution looks simple - wire a feed into the switch direct - question is how far down the cable is it broken - and is it easy to get to. :3Confused
 
Bloody car electrics

 Interesting, might be worth unwrapping that part of the loom and checking for damage, it\'s possible you have uncovered an almighty bodge that\'s starting to fail.  I had an issue where the beams were failing, traced it to some \'interesting\' wiring behind the drives side leg plate. (Right side of the car, just in front of the door - I still shudder when I think about it)

:Thumbsup!

[grinder]

errrr - have you checked my "lights not working thread"

there is a way to raise the lights without the lights coming on

if you take the switch out - and have a look at the block connector - if you put power to one of the pins it will raise the lights - put power to the other one and it will lower them

so might be worth testing this first

mine only had about 9v to the actual switch - and wouldnt raise the lights at all - so i ran a new 12v feed and hey presto - it all worked

although mine didnt raise when at all - regardless of service switch position

i got mine to work by apply seperate 12v feed to the relays - once i proved that they worked at that end - it proved that it was the wiring

infact i had to run 12v to 2 points - one to the relay and one to the switch

not sure if this helps - but might help you track the prob down

Stu

[Prof]

Spot on Stu - just come in from \'fixing\' up a 12V feed to the wire going to the switch.
 
As luck would have it, the wiring loom is exposed just near the rad, under where the air filter box used to live, and the wire I wanted was on top - what a piece of luck :Thumbs-up . I jabbed a pin in it, and then hooked up a multimeter to ground and to the pin, it was at about 12V, took the lights fuse out and it bombed to 0 - so I\'d got the correct wire. Then unplugged the Fog lamp relay and it was at about 0.14V, not going to drive any relays with that much loss :rolleyes:
 
So exactly what you\'ve done - I had two faults as well, feed to relays from main fuse was pants - already fixed that for a previous MOT, now fixed a 12V feed to the switch and all is well - headlamp washers are go, lights raise when you put them on - I am well chuffed init ! :Thumbs-up :Thumbs-up
 
Cheers all for the input.

[grinder]

sounds same as mine

i fed a new wire from the back of the fuse - took me longer to feed it under the front bumper thru all the harness straps than to narrow down the fault !

i used nice purple wire aswell so that i new what the new stuff was ( and it was the only stuff i had spare ! )

glad you got it sorted though

Stu

[batman]

prof might be the easyest way to get some cable and cut out the car and dummy the loom from switch to relay to light direct might be a dodgy feed some where they do call it lazy electric finds the shortest route hope that helps