Headlight Switch

[Beefcake35]

Hi and thank you in advance Have a weird issue going on with my 79 squarebody. when I turn on the lights my dome light comes on. When I turn the dimmer switch it doesnt seem to affect anything. I also noticed I dont get any tail lights or above cab lights. My brake lights work however. Also, I have no dash lights. So- I bought a new switch and put it in and get the same thing. I dont know where to start on it. I checked fuses but could it be some type of ground thing?

Cheers

 

[CRM]

Are you using LED's or incandescent?

 

[Beefcake35]

everything is stock. no LED's

 

[Beefcake35]

so basically the only thing that works with the switch are the headlight and dome light. no running lights, tail lights, licence plate... etc. bright and dim work on headlights. when I fastened the switch to the dash that changed a little. the dimmer switch must be doing something. when I turn the dimmer on the switch it gets brighter.

ok so I removed the bulb under the dash by the 4wd shifter. now dome light works as it should but still no dash or running lights... just headlights

 

[SirRobyn0]

so basically the only thing that works with the switch are the headlight and dome light. no running lights, tail lights, licence plate... etc. bright and dim work on headlights. when I fastened the switch to the dash that changed a little. the dimmer switch must be doing something. when I turn the dimmer on the switch it gets brighter.

ok so I removed the bulb under the dash by the 4wd shifter. now dome light works as it should but still no dash or running lights... just headlights

But just to clarify the doom lights don't work correctly, is that correct.

And No running lights, tail or license plate. What about the front marker lights are they working?

Do you have a trailer hitch with wiring for the trailer, if do taillights work on that?

Glad to hear your running the stock incandescent bulbs, that will make troubleshooting easier.

 

[Beefcake35]

correct dome light works correct. no running lights tail or license plate. front marker lights do not work either... or the above cab lights. I checked the hitch and nothing there either. I do have turn signals and brake lights

 

[Soundmound]

I know nothing about this really. However, I know enough to know, if you're having electrical gremlins- check all your grounds. Seems to be the #1 troubleshooting starting point more often than we'd all like to admit and one we often just omit or forget.

 

[Turbo4whl]

Did you check the fuse for parking lights?

 

[Beefcake35]

went through the grounds that I could find... checked all fuses as they arent labeled and they all were good. I didnt think there was one for parking lights but I will look a bit deeper.... just wondering if that would control the dash lights too.

 

[SirRobyn0]

went through the grounds that I could find... checked all fuses as they arent labeled and they all were good. I didnt think there was one for parking lights but I will look a bit deeper.... just wondering if that would control the dash lights too.

Ok you might want to hit a wiring diagram up, but this is my 2 cents and maybe it'll be of some use to you. I'd pull the switch out again and make sure you are getting power into it like you should and test the wiring going out. Once you do that you'll know for sure if the switch is functioning correctly. If it is then you'd need to check whatever splice comes next & or the firewall connection. IIRC, and I could be remembering wrong but I think there is one power wire to the headlight switch dedicated to the headlights, and one that does park lights, dash ect. Not sure where the dome light gets power from though.

A lot of the answer to this will come from your troubleshooting.

Also it's a 79 is it spade fuses or glass fuses? I ask because sometimes glass fuses can have connection issues. Spades can too but it's much less common.

Oh one last thing if you find your not getting the power you should be to the switch check the fuse box and where the wires run into it.

Hopefully some of this is helpful.

 

[Beefcake35]

it is blade fuses. I checked and I have power going to the switch but havent tracked down a wiring diagram to validate everything. Thanks for your help!!

 

[raylindquist]

The dome lights are hot all the time and the headlight switch gives it a ground just like your door switches do.

 

[raylindquist]

So you probably have a ground issue and it’s feeding back through your dome lights trying to find a ground.

 

[Beefcake35]

would that make the dome lights act weird though? They were but once I pulled the bulb from the floor dome light they work as should

 

[SirRobyn0]

The dome lights are hot all the time and the headlight switch gives it a ground just like your door switches do.

Right, I forgot about that.