longhorn

Hi a couple of days ago when I was pulling my 5th wheel flatdeck I noticed my trailer lights werent working.
I tryed my signal lights and only the ones on the drivers side of trailer were working with no tailights or brake lights.
Thinking it was trailer wiring problems I unhooked the trailer .
Then my cab marker lights and tailights on truck quit working.
It was getting dark but I made it home without tailights.
Thinking I must have fuse problems I started checking the fuses ...............but now my headlights dont work!
Ive had light troubles before but usually the headlights always keep working?
Truck is a 1991 3500
Thanks

handymantim

If the fuses are OK then I'd look at replacing that multifunction switch (turn signal, high beam, etc.)

bmoeller

I suspect a ground problem and/or a bad headlight switch.

longhorn

I finally got time to take out switch.
It looks meleted around one connection so tomorrow Ill buy a new one and try that.
Where should I look for checking grounds?
Thanks for the help.

Desperado

Repalcing the switch should take care of most of your problems, my dads 91 did the same thing, replaced it with a switch for a 1995, now they work great.

longhorn

Ok I put in a new switch and it started to get hot and blew a couple of fuses.
After looking at it close it looks to me like the plug that goes to the switch is burnt?
So I went and cut the whole plug out of another older Dodge pickup and will cut mine out and splice in this other one if the wiring looks the same?
Theres 10 wires coming out of it , whats the chances they are going to be the same between a 1987 and a 1991?

torquefan

That's pretty common. You need to replace the headlight switch and connector. Both are available now in the aftermarket. Then you need to rewire the system so the trailer's tail/marker lights draw power through a relay, because your headlight switch can't handle that much current.

longhorn

Where would you put the relay?
Would I need a relay on every wire going to the trailer?
Thanks for the info.

infidel

Just the wire that powers the trailer's running lights (ones that are on all the time when the lights are on) will need a relay.

My understanding is that most switch meltdowns are caused by running the dash lights way dim, switch gets hot. This can be compounded with added on bulbs on the dimmer circuit such as gauge lamps.
I guess some people have overcome this by drilling a 1/4" hole in the vent duct close to the switch to provide air flow over it.

longhorn

So I got another light switch plug out of a older Dodge pickup.
I cut mine out and went to attach the new one and found out Ive got 2 more wires in mine?
Guess im going to have to try and find a aftermarket one?

infidel

Don't know anout a '91 but for '94-'97 Napa has the switch for $31

longhorn

Thats for the switch right?
Where am I going to find a plug?
I phoned 2 parts places and they never heard of just the plugs?