Headlight Switch getting very hot...Help!

[Northrunner]

Hi Guys,

I own a 1998 12 Valve Quadcab Dually 3500. I did not have a 7-Pin trailer hook-up connector on it, but recently had that added. Now when I tow a trailer, everything works as it should when my headlights are off. But when my headlights are on for about 15 minutes, I get that burning electrical smell and I get some smoke coming out of the dash. It seems to be coming from the headlight switch area and the dash above the switch is very hot.

What are my options for fixing this situation?

Help greatly appreciated...

 

[Ozymandias]

Well seems the one that added your 7pin Harness should do hes job properly - warranty work.

You can be happy that your truck didn't burn down yet.
Smoke coming out of the dashboard.. geeeez...

 

[Wiredawg]

You need to operate the trailer's running lights through a relay, might not hurt to install a relay for the low beams and a separate one for the high beams, using the former light circuits as relay operate circuits. Genos has some nice HD relays.

Even when I had trailer pkg, light switch still a source of heat.

Hope this helps.

Cheers, Ron

 

[KATOOM]

Sounds like whomever installed the 7 pin harness didnt do it correctly. There are plug and play kits for these harnesses too.

 

[Ozymandias]

And a new Light switch please to, a burnt one will give you trouble down the road even if it seems now that it still works ok.

 

[SnoKing]

On my 2nd gen, I had a Britebox kit on the head lights.

 

[GAmes]

Turning the dash lights down increases heat too. It's easy and inexpensive to put relays in the headlight's circuits. The truck came with a relay (or at least a space for one) in the PDC.

 

[Road Dog]

On my 2002 dually there are 2 parking light circuits. One circuit power the truck and 4-pin trailer connector. The second circuit has it's own fuse and relay and powers the 7-pin trailer connector.

Even without the factory trailer plug there should be a 7 wire pigtail for a 7-pin connector. It's usually secured with black electrical tape to the wire harness behind the bumper and covered in mud.

If you're getting smoke you should buy a replacement headlight switch with replacement connector (again with pigtail) and replace the switch and connector.

(A pigtail refers to a wire bundle with nothing on the end suitable for soldering or crimping or screw terminal.)

 

[Northrunner]

Thanks guys. I’ve contacted the guy who installed the 7 pin plug. He’s gonna check out his work and figure out what’s going on.

Then I’ll install a new light switch and pigtail. On the pigtail...I’m assuming I just cut old wires and solder to new ones?

 

[GAmes]

One other hint. If you pull the facia off you can drill a few holes in the top of the vent under the switch. The isn't any circulation there, so if the selector is on chest position the switch will be cooler.

 

[Northrunner]

Well, the guy who added the 7-pin plug is swamped with work and has not made time to double-check the work he did adding the plug to my truck.
He has done this kind of work regularly for 20 years and was recommended to me by the owner of a large trailer sales company. The owner said this guy does all his work needed including on his personal vehicles so I'm inclined to believe he knows what he's doing. What he installed on my truck is the same factory wiring harness found on current year trucks.
But I can't wait for him to make time for me and I'm thinking I would love to be able to help myself. I pulled the dash trim off to expose the switch. Upon examination, I discovered that the pigtail connector that plugs into the back of the switch is what was melting. It looks like it was just one wire that melted the connector at its contact point on the connector. I've ordered a new switch and pigtail.

If I installed a Relay in the pigtail...is that what I want to do to reduce the heat that's melting the pigtail connector?

Thanks to all who've responded.

 

[KATOOM]

If you install a headlight relay kit (or build one yourself) then you'll remove all the stress from the headlight switch coming from the headlights and also allow full voltage to the headlight bulbs. Its a win win item...

Daniel Stern lighting has them if you dont want to mess with putting one together.

 

[Road Dog]

Thanks guys. I’ve contacted the guy who installed the 7 pin plug. He’s gonna check out his work and figure out what’s going on.

Then I’ll install a new light switch and pigtail. On the pigtail...I’m assuming I just cut old wires and solder to new ones?

I like to use a western union splice with shrink wrap.

I think the issue is the 20 or more marker lights on a trailer. The Daniel Stern kits deal with the headlight issue on our trucks (by adding relays to the headlight circuits).

 

[GAmes]

I think the issue is the 20 or more marker lights on a trailer.

The headlight switch only feeds the trailer light relay that is in the PDC, not the trailer lights. That is, if it is wired correctly.

 

[Road Dog]

On my truck, when the previous owner added a connector for a slide-in camper they tapped the truck marker lights instead of the trailer marker lights. At least it blew a fuse when I plugged in my camper. In chasing down the issue I found that the 4-pin trailer connector and 7-pin trailer connector had different marker light circuits. As in, one worked and one didn't with the fuse blown. You'd think that both connectors would use the trailer relay circuit. Maybe there's still some dodgy DIY wiring.

On my '98 a previous owner pulled wires for a brake controller even though the truck was prewired and just needed a controller plugged in. They also tapped into the rear lighting instead of using the existing pigtail.

It's easy to pull the trailer relay and see if the lights still work.

 

[JMarhofke]

Years back there was a TSB for that problem. It was only applied to the 3500 dual wheel trucks since they had the extra lights on the fenders, and the 3 DOT lights on the tailgate. The switch was over heating causing melt down, thus the electrical problems. Since I had some extra lights on my 95 2500, I wanted to updated switch which also included a built in relay. I was able to talk my dealer into selling me one, and I replaced it. I could see on the original switch where it got hot, but had not melted anything. New switch is going just fine with no issues. As mentioned, the dimmer you keep your dash lights, the more resistance/load is put onto the switch. Hopefully someone can dig up the TSB on this, or old post concerning the problem. Good luck with it. On a side note, it was not all that hard to replace the switch myself.

 

[GAmes]

The TSB was for '96 and earlier and wasn't addressing the added load of trailer lights.

 

[JMarhofke]

Didn't remember exactly what all the TSB addressed, but it sure took care of "cooked" switches. I wasn't sure if the trailer lights went directly through the switch w/o relays or not. Thanks for the info.

 

[MHalloran]

I have a 96. Got truck new with a factory installed class 3 hitch. Never used to pull a trailer, just thought it was good to have in case. Back about 15 years ago my headlight switch melted some & stopped working so I had to replace switch in the dash & it’s been good to this day.