rigal02I have a recently purchased 1978, late year build date, that the interior lights don't work. The headlight switch turned counterclockwise does not turn them on. No power at either of the door switches. If i ground the bulb in each of the three lights, they light. Glove box light works, radio works, and dash lights work and dim with headlight switch. I was told that the timer was replaced and they were working prior to me purchasing. Is there a test procedure for the timer? What else might I check? Thank you!
KentvetteukYou may be able to get an idea of what to look for from these (not great!) photos of the Electrical Troubleshooting Manual.
At a quick glance you could check the two fuses mentioned, the CLK LTR CRTSY and the GAUGES fuse, both of which seem to be good for the timer to work.
Based on and experience I had it will be worth checking that the timer unit is fully plugged in!
Adams' Apple
...... If i ground the bulb in each of the three lights, they light.
You answered your own question. Check for good ground at the door switches. If you can ground the sockets, and the lamps come on, then you have power to them....you must have a ground AT the door switches for the lights to work. The delay timer controls voltage to the sockets, as does the light switch dimmer, but the ground comes from the door switch itself. 😉
Joel Adams
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rigal02Thank you Kentvettuk for the pics, I'll be able to get back to troubleshooting this weekend. I'll pull the timer box and recheck the connections.
rigal02Thank you Adams' Apple, I did run a test ground to the door switches to check that but possible didn't get through the rust. I ordered two new switches and hopefully will get them before the weekend. If not I'll pull them out to try to clean them.
KentvetteukAs you're a relatively new owner of the '78, the Electrical Troubleshooting Manual might be a good purchase😄 There are usually a few decent copies on ebay.
But in the meantime I came across this on-line version: https://www.corvettebergen.com/teknisk/1978_corvette_electrical_troubleshooting_manual.pdf
I'm no automotive electrician, but I've found my copy useful for diagnosing a few issues and invaluable when I fitted a new radio and had to unravel "bubba's" work on the radio wiring!😱
Good luck with the car and don't forget, photos are always appreciated!👍
