The Stovebolt Site Forums The Shop Area The Electrical Bay Electrical gremlin with headlights and one turn signal light.

The headlights/tail lights are not working, but did previously. Also, the left front turn signal doesn’t either, but the left rear does as does the emergency flasher. All other lights work as expected. All lights worked fine previously.

Background:
This is a ‘37 Chevy 1/2 ton rewired by the PO to 12 volt with a new, then, wiring harness. I’ve owned the truck some 20 years. Until recently there have not been any problems with the wiring, except for the learning curve in installing a a 7 wire turn signal switch years ago. Even that has worked since then without problems. Also, installed years ago was a rear window mounted third brake light and T/S. It too works as expected.

Done so far:
Inspection of the harness does not show any indication of wear or damage.
Checked grounds—good.
Tested bulbs—good.
Checked in-line fuse—good.
Tested for power in to light switch—no power.
Tested power in to fuse—no power.
As noted above except for head/tail lights and left front T/S light all other lights, including brake, work as expected.
Test failed on wire from harness to LF T/S, but emergency flasher to that light does work.

I am thinking there might be two independent problems internal to wiring harness. Are there any other tests that should be done?

Thanks in advance for any suggestions/help.

The power into the fuse missing is the fundamental problem.

Without power there, you won't get anything downstream.

Agreed.

Need to figure out why that is happening. As stated previously, suspicion is there could be a wiring issue within the harness?

You have at least 2 issues. The signals and the head lights are different circuits.

I would concentrate on the headlights first. Since there is no power at the switch, work from there back to the battery. Check for power at the ammeter if there is one. There may be a fuse or fusible link or circuit breaker between the ammeter and the starter. Follow the wire.

Once you get the headlights working, you can look at the signals.

Yes, agree at least 2 issues as indicated in the OP.

Yes, there is power to the ammeter. That was confirmed. Given there is power to all other lights, methinks power should be going through to the light switch fuse and wiring, which it is not. Also as reported in the OP.

The only signal not working is the LF, but the emergency flasher does work, as do all the others.

So, there in is one “Gremlin”.

Eureka! Found the gremlin! …the man says with egg on his face. The ammeter fuse was blown! It appeared to be good on visual inspection. But, after exhausting all other options and one more under the dash crawl and an another fuse check it was pulled and in better light discovered to have been blown. New fuse, testing of all circuits and issue resolved. I must have unknowingly caused a short while re-wiring the replacement 7 wire turn signal switch. 🫣🫣🫣.