'98 headlight switch

[fest3er]

I may have discovered why these headlight switches have a tendency to melt.

Troooper stopped me on I81 on my way home: no taillights. Whilst it wasn't a stormy night, it was dark and raining a little. No ticket; he let me get off the next exit (¼ mile away) to do something to get lights working in back. Stopped at a gas station with nice lights. Explored the problem. Discovered I had no running lights at all, but the fuse was OK. Pulled the switch and found one spade a little overheated. Couldn't fix that there, so I pulled the brake light switch and drove home with the brake lights on. Much safer for me and everyone else on the road. The running lights did work a week or so ago.

Got home, pulled the switch again and brought it inside. Got the DMM out and, after a while, found there was no connection between B+ and the parking light spade (the slightly overheated one). But there was a connection to the 'post' from the internal contact. I looked closer and saw that that 'rivet' (as it were) was defective. Got my soldering iron, solder and flux out and soldered it. And viola! A good, solid, reliable connection. Reinstalled the switch and the running/parking lights work again.

In short, I suspect many of these switches had manufacturing defects from the factory. The poor connections result in built-up resistance. Resistance results in heat. Enough heat and time, and the plastic melts. I guess I was lucky that it took almost 25 years to fail. Now you inquiring minds know one reason the switches failed.

Now I have to figure out how to fix the plastic on the dash at the top mounting screw; it broke. Hmmm. Maybe some string trimmer line and my old wood-burning iron and weld the plastic back together. That might work. If it does, I might even frankenstein the dash top which disintegrated a few years ago when I replaced the A/C evaporator.

 

[honobiahunter]

Nice. I had a similar issue but opted to swap the pull style switch out for the turn style switch. Found a switch and pigtail at the salvage yard and cut off the truck’s old pigtail and wired in the turn style. Everything works great and eliminate the stress that is/was put on the dash mounting points by the pull style switch

 

[petersonj]

There is too much current flowing through the headlight switch and connectors on these second generation trucks - about 10 amps just for the headlights alone and then an additional 10 amps or so for the taillight circuit when pulling a trailer. Then top it of with a rheostat generating lots of heat for dimming dash lights. All this concentrated in a molded electrical body that houses the switches and slide on connectors. All it takes is one connection with a high resistance to start generating heat that cannot dissipate as fast as it is being generated. It is downhill from there.

There are two things you can do to reduce the electrical load through the headlight switch significantly - relaying the headlights and relaying the taillights. Just doing that will reduce the potential 20 amp load through the headlight switch to far less than 1 amp. No more heat. The switch will probably outlast your truck. Your headlights and taillights will perform much better because you will eliminate the voltage drop from the long path of undersized wiring passing through the headlight switch and dimmer switch . You can get quality relays cheap from a wrecking yard.

My truck has the trailer tow package which provides an OEM relay for the taillights. I relayed the headlights when the truck was new. I am still running the original headlight switch and dimmer switch at 367,000 miles on the truck. The headlight relays raised the voltage at the headlight from 10.9 volts to 13.2 volts. Most headlight bulbs are rated for a specific amount of lumens at 13.2 volts.

- John

 

[AnonEd]

I agree with petersonj. I relayed the headlights on my First Gen (and everything else I owned w/o a relay) and I put a fused relay in the back, powered by a fused supply wire from the battery and triggered from the truck taillight circuit for the trailer plug. When the trailer running light circuit fails, the relay fuse blows, so the truck running lights remain unaffected.

 

[Ozymandias]

Can the pull-switch of the lower level versions be used instead of the turn switch? That one looks better and more solid built and as an open design also not prone to overheating.

 

[BigPapa]

My '98 had the pull switch. It had the woodgrain trim and leather seats, so I wouldn't say it has anything to do with trim levels. The turn style came out in '99.

 

[fest3er]

I think much of the overheating problem with the switches (at least for the design in my '98) is that the external spades are not mechanically connected to the internal contacts very well.

My switch has been in use for almost 25 years. Only the one spade that was inadequately attached to the internal contact showed any signs of overheating. Inadequate attachment means resistance; the dirtier that connection, the more resistance there will be. Resistance results in heat; more resistance, more heat. The dimmer part is open and can get cooling air around it.

I spritzed the internals as best I could with contact cleaner. It works a lot smoother and easier now.

The switch design may have been a little too close to marginal But I think the real problem was poor manufacturing quality. They may have changed to the turn switch after realizing the pull switch had design and manufacturing issues.

That said, I agree that relays are a better long-term solution to handling the current. (Imagine if the full current of the starter went through the key switch instead of through the relay. )

 

[Ozymandias]

My '98 had the pull switch. It had the woodgrain trim and leather seats, so I wouldn't say it has anything to do with trim levels. The turn style came out in '99.

Interesting, my Buddy's is a 98.5 SLT (215 HP) and it has the Pullswitch, but the Operators Manual shows both switches, side by side.
Canadian Modell Truck.

 

[BigPapa]

You can pretty much see everything but the headlight switch……

 

[Ozymandias]

Yeah, that looks perfectly identical, he's Grey and basic, not so nice and welcoming.

 

[Topzide]

On my '01 1500, I found a trailer light unit that had it's own power feed for the trailer lights. Ran fused power to unit, connected the turn signals and running light to unit then to trailer socket. Helps prevent high current load on the switch. Even with the LEDS on trailer, wanted to avoid issues. Don't remember who made it. Maybe an option.

 

[Road Dog]

On my '02 I found that the truck parking lights and 4-pin trailer use one circuit and the 7-pin trailer has it's own circuit (with relay and fuse). The previous owner had added a camper connector and tied into the truck parking instead of the trailer parking. There's a lot of lights on a camper. There's even more lights when I added an ATV trailer (4-pin, no brakes).

I'm not sure how much current goes through my headlight switch. The power goes through the CTM (central timing module) so that the lights turn off after 15 minutes. It could be wired internally a few different ways.