Strange problem with fog-, dash and headlights..,

[Tumbernail]

Hi,
my early 1996 Chimaera 4.0 (MK1 dashboard, serpentine engine and LHD) comes up with new „ideas“ to challenge me with gremlins and issues every quarter since 20 years. The newest one is by far the strangest 🤯:

I lose my headlights, when I push the switch for the dash lights underneath the dashboard.
Dash light remain off, headlights switch of after switch is pressed and come back on after switch is released.

Same happens when I press the fog light after switching on the headlights before.

However, the headlights remain on after pressing the two buttons on the dashboard as long as I do not touch buttons for fog light and / or dash lights (for instruments).

After driving - sometimes - all works for some minutes, but than the problem comes back.

I checked all fuses, they are OK.

I also checked all yellow relays and changed positions of them on the fuse box.
All fine.

Havent got a clue where to start now?

Any idea?

Frank

[Belle427]

Most problems like this point to bad grounds.
I'd check the headlight grounds first which are awkward to access on the front lower body to chassis bolt on the right side under the radiator.
Location can be seen on this thread.
https://www.pistonheads.com/gassing/topic.asp?h=0&...

[Tumbernail]

Thanks! This pictures are really helpful!
I tried it today - losend screw behind radiator, cleaned it and screwed it back in it’s position - Headlights worked for 10 min as the should.
After that same problem. 🥲
Headlights switch off as soon as I put fog lights or dashlights on.😂
So I rested in front of the headlight with a beer - suddenly headlights switched on, fog lights and dash lights were also on.🤩
After switching headlights off and on again, I only get them switched on, when fog lights and dash light remain off.🤪
Will proceed to search, find and clean the other earthing point. 🧐
If anyone has additional ideas … I am happy to hear them.😉
Thanks
Frank

[Belle427]

I would just verify the other ground points are sound at this stage, dont overlook the battery connection too.
The 2 either side of the transmission tunnel are quite important but a pita to get at.

[Tumbernail]

Thanks!
Will Do!
Frank

[Steve_D]

Most likely to be either.
• Earth point top of right-hand tunnel.
• Fuse 10
• The switch control module. Have seen the red supply wire showing signs of overheating.

Steve

[Tumbernail]

Thanks Steve!
Where is the control module located?
Best regards
Frank

[Steve_D]

Tumbernail said:

Thanks Steve!
Where is the control module located?
Best regards
Frank

Under the dash top. Easy to spot as it has the main (18 way) connector and 3 ribbon cables going to the lights, hazards & fog switches.

PM me if you want my circuit diagrams.

Steve