03 ram light problem

I did a starter in a 2003 Dodge Ram a week or so ago and the owner just called me and asked if I could take a look at it. He said that the headlights and foglights are backwards. Basically if he turns the headlight switch it turns the fogs on, and if he turns the fog light switch on it turns the headlights on.

The starter went perfectly smooth and nothing out of the ordinary happened so I can't imagine what is causing this. I can't remember exactly, but I don't think there were 2 different plugs that I possibly plugged in backwards... but I'm not 100% on that. And before anyone asks, yes I used a relay.

Anyone have any ideas? He's coming tomorrow evening for me to take a look at it.

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Kenny
Owner / Technician
KKD Garage LLC
Albany, NY 12205

anyone?

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Kenny
Owner / Technician
KKD Garage LLC
Albany, NY 12205

A few thoughts...

Bulldog and DEI indicates it could be either a 330 ohm or a 1400 ohm resisitor.  While Bulldog shows a relay, DEI and Audiovox suggest using the relay to isolate away from the switch.  In that case the relay wiring would be :

Relay Pin 85 to chassis ground
Relay Pin 86 to to R/S (+) Parking Light output
Relay Pin 87a to switch side of cut Purple / YELLOW Parking Light MUX wire
Relay Pin 87 to chassis ground thru correct resistor value ( 330 or 1400 ohm )
Relay Pin 30 to car side of cut Purple / YELLOW Parking Light MUX wire

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Soldering is fun!

Thats how I installed the relay. I believe it was with a 330ohm resistor. Any other ideas? If it had somehow been wired backwards (it was working fine, but issues always make my mind go to worst case scenerio) could it have done any damage other than to the switch. If I don't find anything, I'll disconnect the light wire completely and see what happens. If it still has an issue then I'll probably end up picking up a new switch and see if it somehow still backfed...

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Kenny
Owner / Technician
KKD Garage LLC
Albany, NY 12205

I have had a few cases where the suggested resistor value didn't quite work.  Used a 5K ohm multi-turn pot to dial in the correct value, then replaced it with a resistor ( network ).

Backwards would have applied an open to the MUX circuit.  The parking lights shouldn't have come on.

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Soldering is fun!

I seem to remember reading this same issue somewhere else. Maybe try changing the resistance going to the switch. Maybe the same wire is used for both the fog lights and headlights depends on what resistance it sees

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If i Can't Install it    I Don't need it   Joe

I'm going to try some different things. I have a feeling its probably just something with the resistor. I did change some things on the parking lights because I originally used the 1.4k and it wasn't working so I had to try a few different values... so its possible (unlikely, but possible) that I may have connected it backwards one of the times and may have sent the signal to the switch instead of the car side. We'll see what happens tomorrow... hopefully its nothing big.

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Kenny
Owner / Technician
KKD Garage LLC
Albany, NY 12205

Well that was interesting. The guy came back and I took a peak at it. Everything was connected properly, so I disconnected the 2 wires at the switch and reconnected the factory wires and everything worked perfectly. So I took another look at the relay and it seemed to be hooked up correctly... so to make things easy I just ran the parking lights out to the relay under the hood and soldered the factory wire back together. So really not sure what the original issue was.

Although now that I think of it, I may have had the resistor on the wrong side of the relay... which would have changed the resistance of the wire (probably just enough to activate the fog lights) and then by turning the fog lights on it brought the resistance up enough to activate the headlights again. That would make sense.... but man what a crazy coincidence... lol.

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Kenny
Owner / Technician
KKD Garage LLC
Albany, NY 12205