[langstonjones]

I'm sure this is simple, but I'm confused. So with headlight switch on I get nothing low beam or high beam. My thinking is that with switch on, I should read 12v across red & black or violet & black depending on which is selected. I get nothing voltage wise. If I pull the multi function switch back like i'm dimming or putting lights on bright, they light up as long as i'm holding it back. I jumpered 12v from battery + and ground to pins on left headlight both red and violet connectors and they both lit up. I've replaced headlight switch and I'm thinking the only thing left could be the dimmer switch. Any thoughts?

 

[Adventurer55]

As far as the multifunction stalk is concerned, it's supposed to illuminate the high beams with the light switch off. Without a wiring diagram it's hard to diagnose your issue.

 

[AllanC]

. . . I jumpered 12v from battery + and ground to pins on left headlight both red and violet connectors and they both lit up. I've replaced headlight switch and I'm thinking the only thing left could be the dimmer switch.. . .

I believe you have methodically isolated the problem to the dimmer switch assembly. It is located on the lower part of the steering column and is activated by a long rod from the turn signal stalk. See attached schematic for a 1988 Dodge Caravan. Wire colors seem to match your truck so this should be an accurate diagram for diagnosis.



Note that the LG wire between the headlamp switch and dimmer switch assembly should have power with the headlamp switch pulled out to 2nd position. Maybe there is a break in the LG wire? If it is intact then the only other possibility is failed or broken contacts inside the dimmer switch assembly.

 

[langstonjones]

I believe you have methodically isolated the problem to the dimmer switch assembly. It is located on the lower part of the steering column and is activated by a long rod from the turn signal stalk. See attached schematic for a 1988 Dodge Caravan. Wire colors seem to match your truck so this should be an accurate diagram for diagnosis.

View attachment 31203

Note that the LG wire between the headlamp switch and dimmer switch assembly should have power with the headlamp switch pulled out to 2nd position. Maybe there is a break in the LG wire? If it is intact then the only other possibility is failed or broken contacts inside the dimmer switch assembly.

Thanks AllanC, I will check the light green wire and then I'll see if I can locate a dimmer if needed.

 

[langstonjones]

Reporting back that dimmer switch did fix the issue. Also, while replacing dimmer switch I noticed something kind of warm and it was this little can looking thing. Does anyone know what it is and if so, why it would be warm? Thanks in advance.

 

[68RT]

Reporting back that dimmer switch did fix the issue. Also, while replacing dimmer switch I noticed something kind of warm and it was this little can looking thing. Does anyone know what it is and if so, why it would be warm? Thanks in advance.

View attachment 72844

Possibly a flasher. Right shape and size. Older style works by heating a bimetalic strip.

 

[langstonjones]

Possibly a flasher. Right shape and size. Older style works by heating a bimetalic strip.

Not sure, but it all seems to be working now and not getting hot.

 

[valiant67]

It may also be a timer for courtesy lights. They are a thermal switch that opens when it heats up.How hot it is may depend on how long the door has been open.

 

[ImperialCrown]

If it is a 3-prong, it is the thermal timer for the 'key-in' illumination lamp on the steering column. It would come on and stay on with the driver's door open.