So I'm trying to figure out whats wrong with my fog lights and things just don't make sense. I am leaning towards a multi-function head light switch or a bad ground somewhere.


So this is what I got:

1999Ram QC 4X4 Sport. In the PDC I have 1 relay for the fog lights. In the pins I cannot find a ground?

1. No ground in Pin PDC.
2. Power readings are strange.
3. When fogs are on I get a .01v at Pink/Orange wire at split on front clip under truck.
4. Ground at Blue wire (at split on front clip under truck) is good.

Now about the strange power readings:

While the relay is plugged in and head lights are on I get full power to each of the 4 pins (3, 5, 2, and 1 (4 is not used) ) on the fog relay. Now when I pull the fog switch (to engage the fogs) I only have full power on #1 only with .14v on all other pins? I tested the Pink/Orange wire at split on front clip under truck for a continuity to ground and there wasn't an issue. The 15 amp fuse in the PDC is good. I switched the relays and same issue?

Now does this sound like a grounding issue or a switch issue?


Illustration purposes only.



1. Black
2. Blue
3. Green
4. Yellow (not used)
5. Red


Last question:

Is there a way to jump the multi-function head light switch to engage the fogs to test for wiring issues?

 

Sounds like an issue in the harness some where, could be the switch but i doubt it. i would consider just re running the wires for your lights and either wiring them directly into the harness for the headlights or to a toggle switch in the cab some where.

 

I made the toggle switch on account of I've ripped off my bumper at least 3 times and the fog's no longer work. But somehow I blew the switch because it no longer lights up and only one light works. Guess I need a new switch and a relay this time.

 

Well after hours of ****ing with it I have narrowed it down to a wiring issue. The sad part is I don't want to spent the $70 bucks just to see if it works. Well the main thing is I would have to special order the switch.


As I see it, the switch is ok and the issue is I get all sorts of current all over the place so I think I am going with the first option and complete re-wiring of the problem. I think I am going to tie into the positive and go through the fog switch (as OEM) and go back to the lights leaving all the harnesses open and pulling the relay. This way the whole system matches as OEM but i don't have to install a switch.

 

We the issue was the the main power wire Pin #86 "RD/OR wire" has a short and needed replaced. I want to include some DIY data.



Pin #86 is the "RD/OR wire" and is the main power supply. This is also the RD/OR wire on the schematics. This is the main power wire for many systems and is protected by a 15 AMP fuse located in the PCM. The Head Light Switch switch is a negatively grounded switch but also a positive switch to ground to BR/YE and finally to BL/RD at the switch. This main wire (RD/OR) goes directly as the the main power wire the Fog Lights so they should be a constant 12volts (hot) then they use the LB wire to essentially ground to the notorious BR/YE and finally to BL/RD at the switch.

All in all the whole system uses a positive as a ground until the switch is actuated to engage the Fog Lights then it becomes a ground but through the switch and Fog Light Switch and illuminates the Fog light on the switch.

All in a nut shell this system gave me 3 days of head ache and a half a gallon of whiskey to figure out. I'm including some Pin info for the PDC and also a Pin Wire color code for further diagnostics.

 

Awesome man thanks, deff saved that

 

No problem,

I put it into the DIY section #56. https://dodgeforum.com/forum/2nd-gen...diy-links.html