About 6 months ago I parked my truck and everything was working fine. It was driven 3 times during that period, then it just sat and was started for brief periods to keep the battery fresh.

I finally have it back on the road and my parking lights or tail lights suddenly don't work. Fuse 50 is fine and I don't see any fuses for parking lights so I'm not really sure where to go from here and what I should be looking at.

any help would be appreciated.

 

check battery voltage and clean all the grounds would be first place to start

 

The battery is doing good, it's a year old Optima Red Top and for the last month or two it's been sitting on a charger trickle charging and remaining fully charged.

Wouldn't bad grounds be causing other issues as well? also, where are the locations of grounds I should be checking other than the one connected directly to the battery?

 

http://www.rambodybuilder.com/2004/d...ingdiagram.pdf has a good diagram of pin out on plugs, great info for a 2004 ,,but check bulbs close,,check sockets for good grounding ,,the FMC module goes to back of fuse box an controls all the lights has been problematic on many ,,check bulb sockets for good grounding and check for voltage at bulb sockets,,check headlight switch as it could fail if its all parking lights are out ,,maybe multi function switch , things like that,,there are clusters of ground wires that bolt to fender around battery under hood, clean those

 

iirc the rear taillights on those years had circuit board issue's. I would check there.

 

I have to replace a burned out tail light bulb so I'll check. I still have brake light functionality though, but I'm really hoping this is a simple fix.
Like I said the truck sat for 6 months without going anywhere, and to the best of my knowledge the lights worked before it was parked....they definitely worked the night I got arrested in it....but I digress, that's a different story and the reason it was parked for 6 months.

I towed a Chrysler 300 with it on a trailer and I don't think the trailer lights worked I can't really remember but I know something was wrong at the time. I've also read that the trailer plug could cause this issue too, not sure how true that is.

 

I have heard towing lights can cause issue an needs to reset in ecu but I have only heard of it an do not know for sure as I never had the issue , seems like it was to protect the circuit if it was shorted out ,,

 

I'm getting 12V at the 7 pin trailer plug for the running lights, but at fuse 15 (50A) I'm only seeing 0.96V

not entirely sure where to go from there. My brake lights work, turn signals work, but I have no parking lamps, tail lights, or license plate lights.

 

I may have found the problem, I think it's the fuse box :/
If I jump the pins on the park lamp relay I get parking lights.

Testing the voltage on the other two pins that activate the relay I don't get any voltage across them so the relay isn't being activated. so it looks like it's a problem with the trace on the circuit board for the IPM, unfortunately I can't really fix it because I can't disconnect my battery due to a device on my car.