troy900ss

I have a 1996 RAM2500 4x4 LB with the factory tow kit installed. Currently I am not getting the 12v to the jack where I plug in the trailer electrical to the truck. The trailer turn signals work and if I jumper the flashing 12v to the turn signal post over to the trailer lights post all the running light flash so I am very confident this is a issue in the Dodge wiring harness not the trailer.

I have the Chilton manual but it is not helpful. Can anyone point me to a schematic of the Dodge tow/trailer kit wiring?

Thanks,

Troy

dslpower

Look at the connectors where the 7way plug wiring hooks to the truck harness for dirt and corrosion.

Also look inside the plug housing (where the wires go in) for dirt, mine was half full of dirt/mud and trapping moisture around the wires and terminals, corroding them badly.

troy900ss

There are two such plugs, of which I have disconnected both and measured voltage. The 1st was a thin 3 wire plug, that has the 12v for the turn signals. The other 4 wire plug is a square and on all 4 pins I get nothing... no voltage, from there it goes back up into the wire harness thus my question. Thank you for the suggestion though, says I am on the right track.

J BODY

From what I can read you have ts and brakes, but no running lights. There is a relay that feeds that circuit in the PDC as well as a fuse for it. The relay feeds 12v to the trailer plug via the blk/orn wire.

troy900ss

Ok, more good information. If the PDC is the fuse box under the hood then I have already replaced the Relay and 40A fuse for the trailer circuit. The blk/orang wire is good info and I can hopefully trace the voltage with that info.

Thanks,

Troy

2003Summit

Check for output from the PDC (yes, the fuse/relay box under hood). Get a schematic off of body builders or wherever you can and carefully locate the output for your trailer lights and test it. Trailer lights are completely independent of the truck lights (fuses, relays and wires). If you are sure the fuse is good but you are not getting output on the bottom of the PDC, it's could be a bad relay.

On an 03, the trailer light relays are actually not user accessible. There are three relays on the underside of the circuit board, sealed in the box: trailer left turn, trailer right turn and trailer running lights (way to go DC for hiding them). If you determine it's a bad relay, you have to physically pop the PDC apart (don't damage it, it's a $600 part!). You can spit the PDC easily enough by drilling out the 3 or so bonded points holding it together (places where you think there should be screws, but instead the plastic is melted to hold it). You only need to drill far enough to break the bond (1 mm or 2 with about a 5/16 bit). Seems to me there is 1 or 2 screws and a few clips along the side. It's not very hard to take apart. You can re-connect your taken apart PDC (put it on a towel or something, you don't want to short anything) and probe to find out which of the three relays is your target. Make sure you understand which relays is which (left, right, tail), I wrote on mine with a marker.

The hard part is getting the bad relay off. I had to physically peal the relay apart with a pair of pliers - bit by bit. Take your time, be careful when you do it so as not to damage the other relays or the circuit board. When you get it down the point where you have the four contacts left, clip them off with side cutters leaving enough of a stub to solder wires onto (or if it's too hard saw them off by hand). Your goal is to not damage the circuit board and leave something to saulder wires to. I then soldered on 6" leads and attached a standard after market relay. There is just enough room in the box to fit the aftermarket relay and re-assemble the unit.

J BODY

.....while good info it is not any way pertaining to the 96 the discussion began with. Whole different animal.

NoSeeUm

Not sure about your truck, but I believe my truck has another connection for the trailer wiring harness that is located in the gap between the cab and the bed.

Jim

J BODY

Yours, in a way, would be much similar to the 96. The connector for the rear harness would be right behind the left front tire up on the frame behind the splash shield. Even though some trucks were not equipped with trailer tow, the PDC often had the terminals and fuse provision, but the wiring would terminate at the aforementioned connector.

troy900ss

Ok I have traced it down to the connector tab that is missing the 12v to drive the lights. However I do not know where this wire runs to. The pin annotated in red is also routed to the connector that jumpers in the trailer brake. However I cannot find where else this wire goes so I have no idea where it is suppose to be connected to 12v? Anyone have a schematic for this circuit?

J BODY

Five O'clock position on your RV plug is the Electric brake circuit. That would be the light blue wire that runs out of your Electric brake. Back in 96 there will be a light blue wire buried up under your dash near the bulkhead or e brake. Seems they liked to "hide" it, but it is there on the trailer tow equipped trucks.

12 volts for the RUNNING LAMPS (blk/orn) is at the 11 O'clock position.