jollyj1956

I have an 84 vette. Need help in trouble shooting why my headlamps quit working last night. While driving I noticed that the right side seemed dim and the high beam indicator was on but dim as well. Got to destination and when I went to leave both headlamps were out and the high beam indicator was on. I checked voltage at almp connectors and have full voltage on both low and high beam regardless of the high beam position. I checked the bulbs directly from the battery and they work. I am really puzzled on this one. Reviewed the manual and the dimmer switch should only allow power only to either low or high beam not both. Has someone had this happen to them? Any help will be greatly appreciated.

AGENT 86

Was this done with both headlights disconnected ?
If not, current can flow to both high and low, as the filaments share the same ground, and the high/low are spliced into the other headlight.
That being said, I would diagnose the ground for each headlight.

G115-on frame, behind LH park/turn lamp
G116-on frame, behind RH park/turn lamp

jollyj1956

Thanks for the reply. I checked the voltage at each lamp connector disconnected from lamps. I thought about the grounds and they appear to be well connected to the frame. Last night I disconnected the dimmer switch and jumped a wire from main yellow hot to tan (low beam) and still no light. I then jumped from yellow to green (high beam) and the indicator light came on but no head lamp. I am stumped. I am not an electrical engineer but this seems pretty basic. Thanks again!

ccrazor

I assume you have 12v on the yellow, there are 2 connectors between the dimmer and each light for both high and low. If you jumper the yellow and a gnd. to the lights do they work?? If they do then you need to do a resistance check on the tan and green wires from the dimmer to the lights. If infinity then you need to find the connectors in the wire harness and check for corrosion.. Connector C115 which comes from the dimmer is located left side of engine bulkhead, C320, below LH headlight, and C323 below RH headlight..

jollyj1956

Thank you for the reply. I will try that tonight and see if a connector is bad. I was concentrating the the switches. I figured that the wiring was right since I had voltage from the light switch to the lamp connectors. I can turn the light switch from headlights to park and the voltage gose to "0". What puzzles me is that I have voltage on both high and low beam wires. The dimmer switch is an either/or switch. So I am wondering if the dimmer switch is messed up allowing power to both high and low wires. Then my other puzzle is if I have voltage at the lamp connectors then why dont the lamps burn. I checked out the bulbs directly from the battery and they work. I will start the trouble shooting process again tonight. Thank You!!

ccrazor

The grounds for the 84 are different from the 86, but I would suggest you make sure they are good..(took a couple of min. to find)..Check from battery pos. to socket ground for 12v..

jollyj1956

Update for those following and helping me solve this problem. I connected yellow wire and tan wires at the dimmer connector and ran straight to the bulb tab and grounded bulb tab to ground connection point. Turned on light switch and light came on. Then I went to the light connector and connected ground to black and yellow and tan to tan and no light. Did a continuity test on all three wires from connector to bulb connection and it tweeted but no light. I checked ground continuity from battery to connector and it tweeted so ground is there. I dont know what I am doing wrong. Any suggestions welcomed.

ccrazor

If you connect the yellow wire to the tan at the dimmer sw., ignition and light switch on, and light bulb connectors on the bulbs, do the lights come on?? Similarly if you do the same yellow to green connection, do the high beams come on?? Have you checked voltage with a volt meter??

jollyj1956

I have not put the ignition on. The lights operate regardless of ignition position, but I'll try anything. I have only been working with the low beam so far. To answer your question I ran a jumper from the dimmer switch connector directly to the lamp tabs and the lamps came on. When I move the jumper to the lamp harness connector that comes from lamp to the first connector in the right lightwell the light did not come on. So I then checked for wire continuity and the meter tweeted meaning wires had no breaks. Yes I am using a volt meter and the readings are in the high 11's. I even checked the grounding circuit and it tweeted as well. I don't know why I have no lights. I must be over looking something, but what

ccrazor

When you check for continuity what is the resistance?? With the yellow connected to the tan at the dimmer switch check for voltage at the lamp connector, if no voltage check from the tan to the battery ground, if no voltage check from the lamp connector ground to the positive of the battery.. This will tell you whether you have a problem with the ground to the connector or in the tan wire..

jollyj1956

I try that, thanks