Strange headlamp failure issue
 

Yesterday I experienced a strange problem with the headlights for my 1995. After a drive where everything was working fine, I stopped and shut off the car and lights for about 10 minutes. When I restarted to drive home, when I turned on the headlights only the right side headlamp motor operated and both headlights failed to illuminate (low beam and high beam). Also, if I operate the lamp motors via the dash board override switch, only the right side operates. The high beam flashers also do not work.

Before I dig in to the schematic, I thought I’d ask the community if there was a “common” failure point that will fail the low and high beam headlamps and left side motor concurrently. Hopefully the answer is not a failed combination switch…

To add, the running lights, turn signals, and all other circuits are still operating.

Any help would be greatly appreciated!

Solved!

So I thought I would close the loop on this post.

Basically, the problems were entirely aftermarket part installation issues and no fault of the car at all...no relay failure, no switch fault, etc. What happened is this:

When I bought the car in 2014, it came with a SBG HID headlamp kit that had been installed by the previous owner. Whomever did the wiring did a bit of a poor job, with wires left dangling here and there. I had done some cleanup of the harness over the years but never took it all apart to really make it right, meaning all wires proper length, no loops of wire, etc. Well this was a mistake as I discovered with this recent problem - the main power feed to the HID controller box (another problem) was excessively long and looped around behind the left headlight bucket. Somehow, I have no idea how, the power lead migrated forward and got tangled in the left headlamp lift linkage in such a way that the wire forced the link arm connecting the lamp housing hinge to pop off the lift motor arm. So that was the reason for one side to work and the other to not lift.

Then, in the process of this fouling, the power wire tore itself out of the HID harness fuse plug, killing the circuit to the HID controller box. However, this also coincided with the controller box itself failing. Probably the box failed directly as a result of the wire damage however even after repairing the wiring the lamps did not illuminate; after a little research it turns out that the controller used in the SBG kit is very inexpensive and prone to failure. My controller showed severe corrosion internally and heat damage from use over time. I was able to get a replacement controller from Amazon that also included a complete HID wire harness for about $13, I cleaned up the original SBG kit plug, did some other harness cleanup with a new fuse holder, and with the new controller box plugged in normal function was restored.

The next step will be to tear out the entire wire harness and replace it with a better quality harness and controller. Probably the Morimoto setup.

Anybody with the original SBG HID kit may want to check the condition of the controller box pins. They are small gauge, and apparently not up to the task of long term operation and over time the internal board and pins corrode and overheat.

For reference, this is the type of controller that came with the kit, and what I bought to replace it. Exact same part, same label, etc.

https://cimg5.ibsrv.net/gimg/www.rx7...f21c8871f2.png

Good to know you sorted it out. I have a SBG kit so I will keep an eye out for issues. Thanks for the info