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problem with headlights not switching

851 Views 5 Replies 2 Participants Last post by  Frankenbird
i will try to list the facts as I know them

everything was working fine before I took the instrument cluster out to install leds. I have the cluster connected now except for the speedo cable and all instrument lights work when I pull the light switch on as well as turn signals

the headlights are not working correctly

when I pull the knob all the way out for the headlights they will come on sometimes, by sometimes I mean if I pull the headlight dimmer lever switch once they will then come on, but if that dimmer lever switch is pulled another time the headlights won't come on when the headlight switch is pulled, at first I could start the lights on low beams, pull the dimmer switch, and get to high beams, but pulling the dimmer switch again would not change back to low beams. Now I get no high beams at all when pulling the dimmer lever switch. I also get no high beam indicator light to come on

I have not put everything back together yet, have the steering column up loosely with just one nut holding it so it doesn't drop all the way

could this be the dimmer switch going bad? or maybe I am missing a ground that got displaced while dropping the steering column? all I had to remove from the instrument cluster to take it out was one pinout in the middle and the speedo cable. should there have been something else that I didn't need to remove because it fell off on its own? should the instrument cluster be grounded somehow besides what is in the pinout?

I do have HIDs on the car running off of a relay to protect the dimmer switch from high voltage. I also have just the 2 hi/lo headlights instead of 4 since my car has had the front changed to a 74. that has all worked flawlessly though since installation.
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I'd make sure that you have battery voltage on yellow wire of headlight switch when you turn lights on. The yellow wire goes to dimmer switch. Make sure you have battery voltage at dimmer switch.

Then click dimmer switch and see if you have battery voltage on either the light green or tan wire coming from dimmer switch. Your testing here to see if dimmer sw is outputting battery voltage to lights.

If you didn't get batt voltage on yellow wire @ headlight sw, the headlight sw is bad. If you got batt voltage from headlight sw and no voltage at dimmer sw. Then wiring to dimmer sw is bad.

If you got voltage into dimmer sw but not out of it on both low & high beam settings, then dimmer sw is bad.

If voltage good with both low & high beam of dimmer sw but headlights don't light, wiring or connectors to headlights bad.

My only question is, does 80 model use floor mounted dimmer switch or steering column mounted dimmer switch? If colum mounted sw, there's the possibility that steel rod that works dimmer sw is not working correctly or dimmer sw is out of adjustment.
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thanks for the reply. my dimmer switch is on the column. I did check my voltage. the yellow wire from the switch checks out good, 11.8 volts. the other wires also have voltage on them. I am perplexed on that since when looking at the electrical diagram I thought voltage should be only applied to one output wire at a time, that I would have a full 12 volts on one wire and zero on the other. that isn't the case though. when the dimmer is one way I get 11.4 volts on both outgoing wires and when the dimmer is swiched I get 11.4 volts on one wire and 4.6 volts on the other. Is that what should be going on? I thought it was wrong so I picked up a new switch and installed it. the new switch reads exactly like the old one. when checked with the ohmmeter one pathway has 0 ohms and the other infinity, and vice versa when dimmer switch is pushed
My understanding of how the dimmer switch should work is that it will have voltage on tan wire in low beam position and voltage on green wire in high beam position.

But not voltage on both. Same with continuity. In low beam where tan wire hooks up and high beam where green wire hooked up. When you checked for continuity, did you have power wire disconnected, as you should do. And both tan & green wire disconnected.

And try testing dimmer switch for voltage with tan and green output wires disconnected.
Yes, I checked continuity with the switch out of the car. I put everything back together thinking just maybe I had a ground disconnected that needed a pathway through something I had removed. things are still the same though. I tested at the relay for the hid's also and have the same voltages showing, 11.9 on both wires when high beam on and 11.9 and 4.5 with the other. I am pretty sure I checked the voltage at the dimmer switch with the outgoing wires removed but I don't distinctly remember if I did. I will do that again to make sure.
issue is resolved. the relay between the hid's and original wiring went bad which back-fed voltage. thank you Robert for the helpful suggestions!
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