85 Carrera electrical issues (help)

[CodyC]

So I have an interesting issue with my Carrera, When i turn the head lights on the speedo will drop. For instance, if Im going around 80 it will drop below 20. Has anyone had the problem?

also, I need to replace my gauge lights (the speedo is completely out) I don't think that would have anything to do with it but you never know...

Any help would be greatly appreciated.

Thank You

[porwolf]

That indeed is a strange situation: Lights on, speedometer drop from 80 to 20 MPH. The first thing I would check is ground connections at the speedometer and at the light bulbs. Do you have the headlight relay kit installed. With that you bypass all the odd current flows through the light switch and the directional switch (high beams/low beams).

[mhicks85]

I have an 85 and I had a similar issue. Some of the gauges would "shift" with the head light on. I found a bad ground connection to the instruments. I bypassed this with a new ground wire. I think I pulled out one of the instruments to get to the wiring.

[CodyC]

Thanks for your input. I will definitely be checking the grounds

-Cheers

[Roger 911]

Yep, probably a ground issue. I just had a similar situation after an engine swap. Gauges worked fine when the lights were off, and then either the speedo or the tach quit working when I switched them on. Loose ground.

Roger