MOT tomorrow - Electrical hell today

[Philpooma 30]

I’m hoping that someone here can point me in the right direction of what I need to check on my car.

i have just finished a full restoration on a lovely Grey Gti, briefly test ran the car yesterday prior to its MOT and all was well.

This afternoon, just checking all the lights etc one more time just to be sure and all hell broke lose.

 

When I turn the side lights on - All works as it should.

 

When I go to dipped beam - Windscreen wipers come on, All the dash warning lights come on, both spotlights come on, but not the headlights.

Then when I try to turn the lights off at the stalk, one headlight comes on, both spotlights stay on and all the dash lights too.

At this point hazards and indicators dont work and the only way I can get the above to turn off is to disconnect a battery terminal.

 

I’m OK on basic electrical issues, but dont know where to start with this one........

 

Up to this point all lights, indicators, wipers etc were working as they should.

[PhilNW 44]

Might be any earth has come off/broken

[Philpooma 30]

3 minutes ago, PhilNW said:

Might be any earth has come off/broken

Thanks Phil, I’ll go through the earths tomorrow. And see what I find.

After that, all that ai can think of are relay issues.....

As I said my electrical knowledge is very limited

Cheers Phil

[PhilNW 44]

Try the earth blocks behind the headlights for a start

Edited September 30, 2020 by PhilNW

[welshpug 1,662]

definitely nearside earth issue, Have had a similar problem, power will go back up the earth and trigger a different circuit when it reaches a common block where its connection to the body is poor.

 

had me baffled for a while but it is possible!

Edited September 30, 2020 by welshpug

[PhilNW 44]

14 minutes ago, welshpug said:

definitely nearside earth issue, Have had a similar problem, power will go back up the earth and trigger a different circuit when it reaches a common block where its connection to the body is poor.

 

had me baffled for a while but it is possible!

+1

 

The joys of 30 year old French electrics....

[Philpooma 30]

1 hour ago, PhilNW said:

Try the earth blocks behind the headlights for a start

Its weird as I have recently been through all the earths on the car getting everything working again after disconnecting and then reconnecting the wires during the resto. All working well yesterday.

I’m familiar with the earths on the NS, I’ll start there in the morning and see what happens,

thanks

[Philpooma 30]

1 hour ago, welshpug said:

definitely nearside earth issue, Have had a similar problem, power will go back up the earth and trigger a different circuit when it reaches a common block where its connection to the body is poor.

 

had me baffled for a while but it is possible!

Great Mei, thanks for the feedback, great to hear confidence on what the issue is.

I’ll let you guys know how it goes tomorrow

[Philpooma 30]

@PhilNW & @welshpug Happy to report that the fix was simple. Checked the earths to find that the Inner wing earth behind the washer bottle was not tightened up properly. Once tightened up, everything was back to normal.

During the rebuild i have been very careful to tighten everything up to the correct torque and have marked every nut and bolt with white paint to confirm......apart from inconsequential bolts like this one .

 

Anyway, thanks again for the responses and support

[PhilNW 44]

[SweetBadger 94]

What is it about electrical gremlins just before before the MOT!?

 

The evening before the MOT on the new race car was due the indicators stopped working - ended up with bits of the dash out, and disassembling the indicator stalk in the hunt for the problem (not recommended - was a total bastard to get that back together!).

 

Turned out to be a loose hazard warning switch which was being held in slightly by the dash trim - if you slightly press the hazard switch, then the circuit between the indicator stalk and indicators is broken! Took me till 11pm to find the problem!

 

When is the MOT?  Good luck with it.

[Philpooma 30]

8 hours ago, SweetBadger said:

What is it about electrical gremlins just before before the MOT!?

 

The evening before the MOT on the new race car was due the indicators stopped working - ended up with bits of the dash out, and disassembling the indicator stalk in the hunt for the problem (not recommended - was a total bastard to get that back together!).

 

Turned out to be a loose hazard warning switch which was being held in slightly by the dash trim - if you slightly press the hazard switch, then the circuit between the indicator stalk and indicators is broken! Took me till 11pm to find the problem!

 

When is the MOT?  Good luck with it.

Its horrible when things go wrong at the last minute, even after you have prepared the car well in advance.

It was a good ending for me today though, car flew through the MOT, the guys at the test station loved the car and were very impressed with the build .

Need to put a few miles on the engine now to run it in

 

[Telf 224 2 Cars]

nice work! mine had a issue just before MOT- no lights , then crazy flashing lights, then no indicators- same issue- loose earth.

 

Good to see you have finished it.

 

Probably just the camera angle- front arches look a little high? this was another problem i also had!