Electrical wiring and power problems!

[corradofuze 0]

I had my car in the garage for some minor interior work and when i got the car back vie had nothing but problem with the electrics, the idiots that did the job (the have moved now conveniently) have left the car in a worse state than before. but anyway, the electrics are all messed up, ive checked fuses ect; what happens is, if the headlights are off everything works but if you turn the lights on the revs drop by half and the speedometer and petrol gauge all stop working asif someones flicked the off button. plus the oil light keeps coming on and beeping but i have had the oil filter and earthing changed! thanks a lot all help is appreciated.

[tony_ack 0]

I would suspect it's the dash lighting that's contacting something it shouldn't, especially if the work was to the interior.

 

On my MK2 16v someone had connected a spare plug on the ISV controller behind the dash to a spare accessory lighting plug on the back of the fusebox - the result was that every time I turned the lights on, the car ran really rough at idle and hunted like crazy. Obviously your problem is more widespread than that, but it could be something similar.

[corradofuze 0]

so do you think that the dash will need taking out and re wiring again? thanks a lot tony.

[VR6Pete 0]

What work did you have done initially. This might shed some light on the problem.

[corradofuze 0]

i had my heater matrix fitted and my gear linkage at the same time. it then started to work irratically. seems like the wiring is done wrong .

[tony_ack 0]

I wouldn't say it all needs re-wiring, but there is clearly something in the lighting circuit (either dash lights or vehicle lights) that is contacting something else that it shouldn't. I'm trying to think of something in common between the lighting, engine running, speedo and fuel gauge... all I can think of is the clocks themselves? Does the ECU use a speed reading or engine speed reading from a speed sensor in the clocks?

 

To be honest, it is guesswork at the moment - this looks unfortunately like it may be a job for a VAG-friendly electrician that knows a bit about CE2.

 

---------- Post added at 05:00 PM ---------- Previous post was at 04:50 PM ----------

 

Just noticed you've also got a 1.8 16v, which is the same engine as the Golf I was having trouble with. It's a long shot, but it may be worth checking the green wire from the ISV controller isn't plugged into a spare plug coming out of D12 of the fusebox (assuming that the Corrado setup on that plug is the same as a 90 spec Golf).

 

I've even got a pic (it's the green wire in the centre on top of the fusebox, plugged into the grey/blue wire - they should NOT be connected) :-)

 

 

Not saying it's definitely that, but may be worth a look. If someone disconnected the ISV controller to get the matrix out (ISV controller is behind the centre console), then when they put it back in, they probably saw a loose wire from the fusebox, and a loose wire from the ISV controller, and though 'Ah, that must go in there!'