I was about to go get my 86 hatch inspected, and I noticed something odd. The right side headlights work great, but the left side, and the taillights are dim, very dim. Like they are not getting full voltage. I have'nt had a chance to get to involved, but the left headlights were only getting 4-6 volts. The right side was getting 8-9 volts. I pulled a tailight and the filiment was barely red, I thought it was blown when I first looked at it. And you cannot see anything thru the lense.Blinkers and brake lights are fine.

I'll break out the wiring diagrams tomorrow.

 

Anyone seen this before?

I think you may have a ground problem. The ground for the headlights goes back to the dash area I believe. It may also be a switch problem. Having your meter handy and a good diagram should help you locate the trouble real quick.

I got it!

 

After tracing all the wires, checking all the connections, checking voltage everywhere, I found the problem, bad relays. Probably just one, but I replaced both.

Interesting thing, I went to the parts store to get some, and they crosed the number on the old relays to a new one that cost $9.99 each. Out on the shelf, unknown to the counterperson, where two Pilot brand, driving light replacement relays for $3.69 each, that where the same configuration, but where 30 amp, instead of the stock 22 amp. Fixed it, and modified it for less than half the price!

 

 

Later

Good work on the problem. Thanks for the feedback.