I have a weird one. 1998 2500. With wipers off, turning on the left blinker/indicator causes the wipers to turn on steady. Turning on the headlights causes the wipers to swipe once then park.

I've ruled out the multifunction switch by trying another with the same result.

Swapped the blinker relay with the same result.

Unplugging the CTM under the dash stops this and allows normal blinker function and headlights with no wiper, but I loose intermittant wipers of course. Installing another CTM results in the same problem.

Strange eh? Any thoughts?

Rob

 

Is this a new-to-you truck? Or did this just start and you've had the truck for a bit? Sounds, at first blush, like your wiring is messed up. Your headlight switch is on the dash, right? Or do you mean when you flick the highbeams on?

 

Well, wiring has definatly been disturbed. Cab swap thread here where I had other issues: https://dodgeforum.com/forum/2nd-gen...ow-no-bus.html

However, all said and done, all wiring is now a 98 including engine, cab/dash, and back.

Grounds were closely scrutinized during the previous round of troubleshooting.

Headlight switch is a pull **** on the dash.

Rob

 

Oh, you're THAT bobbywolf...

Just kidding

Heading out the door right now but I'll check the schematics tonight and/or tomorrow.

 

Still working on this...

You moved the 98 wiring into the newer (which year?) cab. Did you try the 98 multifunction switch too? You said that you tried a different one, just trying to nail this all down. And, maybe, the headlight switch too?

 

The mfs tried was from the 00. All parts tried were in fact.

Yes, all wiring was swapped except the cab dome light/3rd brake light wiring under the headliner. The entire 98 dash was swapped in with wiring attached.

 

You obviously have something back-feeding voltage to the wiper circuits. But, for the life of me, nothing is jumping out at me. Disconnect the plug to the wiper switch, turn on the left blinker, then the headlights and see what happens.


I assume that the wipers/switch work normally.

You might also try disconnecting the CTM (central timer module) and test things.

Next thing will be disconnecting other dash plugs to see what happens. Sounds like the only way to find this will be by the process of elimination. Like the blinker plug, then try the headlight problem. Disconnect the headlight, then try the blinker problem. Then dash gauges, maybe even radio.

 

Isn't the wiper switch part of the multifunction switch? Yeah. That's gonna be fun.

 

Yeah, thought about that didn't look too closely at the schematics and I was hoping that they had different plugs for each. Maybe?...


I'd start with the CTM anyways.