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I have been troubleshooting my 1977 C3’s dimmer switch for a few days and saw someone post that if it clicks it works. Good news is that it clicks if you pull back on the dimmer and push the rod manually at the same time. Which leads me to my next step which is adjusting it. I’ve have linked the adjustment instructions. Is there anyone that has adjusted it and could give me tips. Please note the step and anything you would add to make the job as painless as possible. I would prefer not to remove the steering column since there is an access panel under it.
I'm trying to understand the reason for troubleshooting the dimmer switch...
Do you believe the switch is bad or do you believe the switch is out of adjustment...
The adjustment part is like set it and forget it...
Unless the ignition or dimmer switches have been moved or replaced there should be no reason to mess with the position of either...
Here is the headlight circuit drawing for the 77...
The Lt.Blu wire is coming from the headlight switch, the switch path as shown in the drawing is Low Beams...
So to test the switch you would have continuity between Lt.Blu and Tan for Low Beams & Lt.Blu and Lt.Grn for Hi Beams...
If your having a different problem with the dimmer please explain better...
The dimmer switch is down on the column, just under the lower cover on the left hand side.
The question is. Why are you pulling manually on the rod? And just how are you doing that? And just because it clicks certainly doesn't mean you are getting a electrical connection.
Just what is going on here? Adjusting the switch is a simple matter of loosening 2 screws, sliding the switch and tightening the screws. But manually pulling the rod?
I am confused.
I'm trying to understand the reason for troubleshooting the dimmer switch...
Do you believe the switch is bad or do you believe the switch is out of adjustment...
The adjustment part is like set it and forget it...
Unless the ignition or dimmer switches have been moved or replaced there should be no reason to mess with the position of either...
Here is the headlight circuit drawing for the 77...
The Lt.Blu wire is coming from the headlight switch, the switch path as shown in the drawing is Low Beams...
So to test the switch you would have continuity between Lt.Blu and Tan for Low Beams & Lt.Blu and Lt.Grn for Hi Beams...
If your having a different problem with the dimmer please explain better...
the circuit is working the rod that connects the steering wheel pull function to the actual switch is bending slightly which is not giving it enough pressure to depress the switch. When I manually push the rod in it clicks and the high beams go on. So in this case the switch has to be moved a hair forward so it has less play.
The dimmer switch is down on the column, just under the lower cover on the left hand side.
The question is. Why are you pulling manually on the rod? And just how are you doing that? And just because it clicks certainly doesn't mean you are getting a electrical connection.
Just what is going on here? Adjusting the switch is a simple matter of loosening 2 screws, sliding the switch and tightening the screws. But manually pulling the rod?
I am confused.
pushing the rod that connects to the switch under the steering column triggers the high beam circuit. There is too much play in the rod that connects the lever to the switch so it does not trigger with the toggle lever by the wheel.
So if it's just an adjustment using a 3/32 drill bit depressed the plunger portion of the switch (the section of switch where the rod fits into) and align the holes then insert the drill bit. This is the home position. Slide the dimmer switch bracket so the rod stops into the plunger socket securely. Then tighten the mounting screws. Make sure the ignition switch stays in it's place when making adjustments.
Pushing the switch plunger in so the 2 holes align this is where the 3/32 Drill Bit fits (Red Circle & Line )...
Last edited by bmotojoe; Jan 20, 2026 at 08:01 AM.
So if it's just an adjustment using a 3/32 drill bit depressed the plunger portion of the switch (the section of switch where the rod fits into) and align the holes then insert the drill bit. This is the home position. Slide the dimmer switch bracket so the rod stops into the plunger socket securely. Then tighten the mounting screws. Make sure the ignition switch stays in it's place when making adjustments.
Pushing the switch plunger in so the 2 holes align this is where the 3/32 Drill Bit fits (Red Circle & Line )...
so let me get this straight… the drill bit helps make sure the spring tension is contained where the rod goes in. After this I can unscrew and push the switch until it’s seated on the rod. Then tighten screws and remove drill bit. How do you make sure the ignition switch doesn’t move? I’ve seen this mentioned before.
Headlight Dimmer Switch Rigging
