mikey

ok, odd electrical issue here.. '64 vette, but I made my own forward lamp harness because of a custom headlight setup. low beams only, no high beams. original turn signals.

over bumps, i would assume due to a loose connection somewhere, my headlights flicker off and simultaneously the dash indicators for BOTH turn signals flicker on. this strikes me as quite odd since left and right turn signals are fed by two different wires and the headlamps are powered by their own wire.

also, without the headlamps on, only the running lights, over bumps both dash indicators for turn signals blip ON.

the condition occurs when the front wheels strike the bump and it is very brief blip.

i had a friend stand outside the car and verify outside light action with the running/turn lights. it seems that when the dash indicators flash, only the front turn signals flash also, but not the rears. so all together, two front amber bright side of bulb flashes on as does the dash indicators for these bulbs. the rears do not flash. if the headlights are on, they flicker off at the same moment.

i am suspect of wiring behind the cluster at this point and guess i will pull it out (again) to re-check connections. the dash harness is new.

other than chasing all the connections looking aimlessly for a problem that i can't duplicate in my garage, anyone have an electrical explanation for what's happening?
i could understand a loose ground causing a flicker OFF for the headlights, but how are the front and dash turn signals flickering ON?

chrislyn

Mikey ,you are having a feedback issue. Check all your ground connections.

magicv8

IMO probably loose or corroded contacts in the LH bulkhead plug that feeds all the lamps.

Disconnect the battery before carefully removing the plug.

Trophy Blue

Clean the dimmer switch connection as well.

mikey

well i'm still stuck on this one.. bulkhead connector is in great shape, i bought a new LL under dash harness with fuse block and a kind forum member gave me the bulkhead connectors for my custom engine bay harnesses which were in near new condition..
i'll re-check grounds, but i don't understand what a loose ground has to do with the turn signal indicators coming on.
the turn signal indicator blips i confirmed occurs in either running lamps or headlights modes, but not in lights off mode.
i could understand a loose ground causing headlights to flicker, but this situation with the turn signal indicators both flashing at the same time confuses me..

i played with the headlight/dimmer switch connection as well in the garage and couldn't duplicate the problem.

mikey

original post updated with newest information, still hunting for root cause..

magicv8

the headlamp problem may be the connection to the headlamp switch from the new harness, or may be the switch, or may be the floor switch.

The turn signal switch/harness/connector may be bad or pinched. Unless the main dash harness turn signal indicator wires are pinched against a head/turn/park/tail line, the only way to light both turnlamp indicators is through the turn switch. Something in the headlamp/parklamp lines is feeding the turnsignal lines, and it could even be at the stop/tail lamp connectors, harness, or sockets. If you look at the wiring diagrams linked in the help section near the bottom of my home page, you will see that the headlamps and park/turnlamps share a ground connection. If the ground is unstable and a connection can be made through corrosion, pinched wires, or cross connections elsewhere in the harness, that path will be followed.

1 Unplug the rear harness connection to the main dash harness and test (lights on) to see if the problem goes away.

2 If not, reconnect the rear harness, unplug the LH bulkhead harness, and test (lights on) to see if the problem goes away.

3 If not, the problem is in the cabin.

mikey

thanks magic. that diagnostics method makes sense.. i will give it a try this weekend to hopefully isolate which section of the harness has the issue. more to follow!

mikey

well just a courtesy update, cuz yeah, sometimes it takes me a month to get back out to the garage and fix things..

after a couple hundred more miles, the symptoms got weirder.. the right front amber would blink the dim filament with the turn signal and the bright filament never lit. neither filament came on with running or headlamps, but the dash indicator stayed on solid.

i finally found a loose ground connection, i apparently crimped the ground wire wrong in the ring terminal for the front right amber light.

ground wire fixed, all lights appear to be functioning normally again, at least stationary.. i still have to drive and hit some bumps to make sure the flashing symptom is gone.

chrislyn called it on the first reply to this thread! feedback is the only thing that explains the weird lighting.. current was looking for another way to ground when the primary ground was lost i guess..

cheers!