A3 tdi 2.0 dash lights

[Stecon]

Hi all
I’ve been rebuilding an A3 2.0 tdi Quattro 2005 and I’m struggling to find the fault in the dash lights
When I turn the ignition on everything lights up nice but when I start the engine it all goes dark all the back lighting behind the clocks, radio and the climate control and the screen in the clocks goes out as well completely dark as in no power.
With the ignition on without the engine running it all works fine even the dimmer wheel works
I’m getting a good charge voltage and the headlights work fine

Any thoughts, ideas on what to check would be greatly appreciate

 

[SootySport]

As it’s been off the road for a while, I think the battery has run down charge wise. If you left the car running for a lot longer or drive it the battery would build up charge and lights would recover.
I’ve rebuilt a few cars over the years and the battery always suffers by being disconnected or out of the car and always ended up by buying a new one.

 

[Stecon]

Hi thanks for getting back
The car was doing this with the previous owner as well that’s one of the reasons I got the car cheap as for the battery I’ve kept it charged the whole time the cars been off the road and it’s not the same battery the car came with

 

[SootySport]

There are some threads about no dash lights on this forum, not all the same problem though.
Have a search.

 

[Stecon]

From what I’ve found it seems more about the screen in the clocks not about the back lights going out

I’ve also noticed the screen on the climate control goes out as well but still blows air

 

[SootySport]

Beginning to look like a power feed problem. Have you gone through the engine bay fuse box looking for corroded connectors, fuses. Check both sides of the fuse panel for water marks.

 

[Stecon]

I have found one not sure where it goes I’ve cleaned that one it was one of the 10mm nuts, but didn’t know that there was connections on both sides
So that’s my next port of call thank you

 

[aqibi2000]

Hi mate

what is the measured voltage in the cigarette lighter/fuse box when the engine is running?

A damaged voltage regulator at the alternator can increase the voltage well over 20V a threshold at which which many ECU turn off.

 

[Stecon]

Hi mate

what is the measured voltage in the cigarette lighter/fuse box when the engine is running?

A damaged voltage regulator at the alternator can increase the voltage well over 20V a threshold at which which many ECU turn off.

I’ve got no power at the cigarette light engine on or off I’ve even pulled it and tested at the connections, at the battery I’ve got 14.15v

 

[aqibi2000]

I’ve got no power at the cigarette light engine on or off I’ve even pulled it and tested at the connections, at the battery I’ve got 14.15v

Very unlikely the cigarette lighter fuses is blown coincidently if it was all working before, it’s likely the main feed to this further up may be open circuit.

As mentioned by Scooty you need to check the m8 terminal fuses in the engine bay to see if one is blown and clean the corrosion on the eyelets of the connecting point (green crud).

 

[Stecon]

Thanks for getting back I’ve checked the engine fuse box and I’ve got a constant voltage either side of the 10mm nuts as for the cigarette lighter that was just a blown fuse, I’ve got the same voltage at that as the battery now

 

[Stecon]

I’ve been reading other posts and can’t find one with the same problems as mine because my cluster works it’s just the back light on all the dash and the display for the climate control and the display screen in the cluster