The truck in my sig came with a utility box on it that was wired up and working, but the wiring was kind of a mess. A bunch of wiring in the cab was also messed with, such as a brake controller that was installed, etc., plus I took apart the dash in order to work on stuff so it's possible I might have messed something up.

After I cleaned up the mess at the back of the frame and sorted out which wires were the factory originals (practically all of the utility box wiring was heavy-gauge gray stuff, no color coding), I wound up with these wires:

Black/yellow - Tail lights
Brown/yellow - Supposedly right turn lights/brake, but acting as hazards/brake
Green/yellow - Can't get it to do anything, should be left turn lights/brake
2x Violet/Black - Should be backup lamps (haven't tested)
3x Gray - All of these are grounds. For some reason the added-on ground at the back of the frame that the utility box used wouldn't work after I took it all apart.

This is after the point in the harness where the RWAL stuff is spliced in. Oddly my wires correspond to "Sweptline box" rather than cab & chassis according to the wiring diagram I found on 1stgen.org, but my frame was lengthened so that might be why.

So basically, at this point I have brake lights, hazard lights, and tail lights, although the hazard lights are temporarily only on the right side because that green wire doesn't do anything! Furthermore, I have no turn signals at all. I'm pretty sure they worked before I started taking the truck apart, and it's absolutely NOT the flasher or fuses, since I've checked those a million times, and the connections on the back of the fuse holder look fine. By "no turn signals at all" I mean that I don't even get one of the front turn signals to light up - absolutely nothing happens. The hazards on the front work just fine.

Help!

 

Have you tried a new turn signal flasher?

 

Yeah, I've got two regular ones and one electronic one, and all three of them work perfectly in the hazard flasher slot.

 

Since the fronts won't work I'm thinking turn signal switch but I'd like to troubleshoot it further before throwing parts on it if it was my truck.

Multifunction turn signal switch or old-school wipers on the dash?

 

Multifunction type. There's way too many wires coming out of the steering column

Unrelated but I just noticed this... why is there a switch of some kind on my accelerator pedal?

 

Does the truck have an exhaust brake?

With the multifunction switch unplugged, key turned on:

You should have power on the red and black wire.

Look at the switch connector. The side with the ridge will be considered the "top". It's numbered left to right in rows, cavity 1 being top left. This is as viewed from the wire end, not the switch end. Clear as mud?

Anyway, set your meter for continuity/ohms.

Signal lever left = continuity between pin 13 and 16, and between 13 and 15.
Lever right = continuity between 13 and 12, and between 13 and 11.

If this is not the case, the switch is bad.

 

No exhaust brake, pretty sure it never had one either as it's a 727. The two wires coming off the switch don't go anywhere, and make me think it's an aftermarket thing. Pushing the fuel pedal makes the switch turn on, same as the usual brake lights switch.

I took the cover off the turn signal lever (multifunction switch?) and located the gray junction box that contains all the plugs that seem to come out of the steering column. I can't find anything that matches what you're describing though (no numbering on any of them).

These are the wiring diagrams I'm looking at, specifically Scan26 and 27: http://dens-site.net/Dodge_CTD/1991.5-Wiring_Diagrams/

 

The numbers aren't literally on the plug, they are just used to refer to the holes. Re-read my last post and you will be able to figure out which holes/pins to check.

 

Yeah, I just figured that out looking at the wiring diagram again. 13/16 and 13/11 are the only ones with continuity, and ONLY with the hazard switch on - turn signal switch apparently does nothing for the turn signals (the wipers, high beams, and wiper pump all work). How'd that happen?

 

Sounds like the switch is toast. Get a new multifunction switch and things should be OK.