trailer lights with factory connector
#1
07-01-2005, 05:02 PM
trailer lights with factory connector
Hello all my fellow Ford truck owners..
I have a 1995 F-150 supercab that is ten years new this December..I have a 5.0 engine and the auto trans is a 4r70w. with 189194.2 miles I have had this truck since day one and it has been very relialbe for the past 9.9 years, no major work has been done. The truck has not needed it. Now that the small talk is over lets get down to bussiness
Here recently I noticed while towing I had only a turn and tail light working on the trailer both on the left side. after some trouble shooting I found that my 25A fuse located in the power dist box ( engine compartment) fuse 4 D was blown. I replaced the fuse and the only improvement was that the running lights along with the left turn / brake was working. I them replaced relay number 4 trailer/ marker lamps (relay) and there was no change. what the hey only 20 bucks.. so then I took the trailer harness out of the back where it plugs into the rest of the harness. I tested it all seven wires for continuity and it rang true all wires are intact and fuctioning fine...So here is my problem....The fuse is now intact there is a new relay an it seems to be fuctioning as well as the OEM relay and the trailer harness is fine but still no right hand brake light or turn nor running light at the tail light (trailer and yes I checked the bulbs and wiring the trailer lights up on my dads truck)....I figure the collective brain power here may stirr me into the right direction...because the rest of the lighting on my turn works fine all signals and brake lights and running lights... so please if you have experienced this problem or know of a work around for fixing it...let me know ..i dont want to have to pull the bed off to trace the entire wire loom....
I have a 1995 F-150 supercab that is ten years new this December..I have a 5.0 engine and the auto trans is a 4r70w. with 189194.2 miles I have had this truck since day one and it has been very relialbe for the past 9.9 years, no major work has been done. The truck has not needed it. Now that the small talk is over lets get down to bussiness
Here recently I noticed while towing I had only a turn and tail light working on the trailer both on the left side. after some trouble shooting I found that my 25A fuse located in the power dist box ( engine compartment) fuse 4 D was blown. I replaced the fuse and the only improvement was that the running lights along with the left turn / brake was working. I them replaced relay number 4 trailer/ marker lamps (relay) and there was no change. what the hey only 20 bucks.. so then I took the trailer harness out of the back where it plugs into the rest of the harness. I tested it all seven wires for continuity and it rang true all wires are intact and fuctioning fine...So here is my problem....The fuse is now intact there is a new relay an it seems to be fuctioning as well as the OEM relay and the trailer harness is fine but still no right hand brake light or turn nor running light at the tail light (trailer and yes I checked the bulbs and wiring the trailer lights up on my dads truck)....I figure the collective brain power here may stirr me into the right direction...because the rest of the lighting on my turn works fine all signals and brake lights and running lights... so please if you have experienced this problem or know of a work around for fixing it...let me know ..i dont want to have to pull the bed off to trace the entire wire loom....
Last edited by Jack01; 07-01-2005 at 05:04 PM.
#2
07-01-2005, 06:02 PM
What do you mean about "wiring the trailer lights up on your dad's truck"?
If you have all good connections on the truck then it HAS to be the trailer. It could be a bad ground on the right side. Or, the bulb on the right could LOOK fine but not be. I would switch the left and right side bulbs on the trailer and go from there.
Good luck!
-Matt
If you have all good connections on the truck then it HAS to be the trailer. It could be a bad ground on the right side. Or, the bulb on the right could LOOK fine but not be. I would switch the left and right side bulbs on the trailer and go from there.
Good luck!
-Matt
#3
07-01-2005, 06:11 PM
To track the problem down troubleshoot the truck with the trailer disconnected. You need to get all of the brake lights, running lights and turn signals working on the truck first.
When all the truck lights work right, take voltage reading between the truck's frame and each pin of your trailer connector. Assuming that you have the factory tow package and the standard 7-pin trailer connection pin 1 (top) should be backup lights, pin 2 (next pin clockwise) is trailer battery charge, pin 3 is trailer right turn signal, pin 4 is trailer brakes, pin 5 is trailer ground, pin 6 is tailer right turn and pin 7 is trailer running lights.
Fuses for the trailer stop/right and stop/left turn signals are in the engine compartment fuse box (fuses F and G, 10 amp each). Fuses for the running lights are in the cab. The relays in the engine compartment trailer tow add-on relay box are for the trailer backup connection and the battery charge connection only. Relay 4 in the engine compartment fuse box is for the trailer running lamps and it receives power from fuse 4 in the truck's cab fuse panel and from fuse D (4) in the engine compartment fuse box.
Once the truck is OK, troubleshoot the trailer without it connected to the truck's wiring harness. I use a 12 volt battery and a couple of jumper wires. Connect the battery negative to the trailer's frame and touch the positive lead to each of the trailer's connection pins for running lights, turn signals and brakes one at a time. This will track down any problem with the trailer's turn signals, running lights or brakes.
This is easier than it sounds. You will probably find that fuse F or G blew.
Lou Braun
When all the truck lights work right, take voltage reading between the truck's frame and each pin of your trailer connector. Assuming that you have the factory tow package and the standard 7-pin trailer connection pin 1 (top) should be backup lights, pin 2 (next pin clockwise) is trailer battery charge, pin 3 is trailer right turn signal, pin 4 is trailer brakes, pin 5 is trailer ground, pin 6 is tailer right turn and pin 7 is trailer running lights.
Fuses for the trailer stop/right and stop/left turn signals are in the engine compartment fuse box (fuses F and G, 10 amp each). Fuses for the running lights are in the cab. The relays in the engine compartment trailer tow add-on relay box are for the trailer backup connection and the battery charge connection only. Relay 4 in the engine compartment fuse box is for the trailer running lamps and it receives power from fuse 4 in the truck's cab fuse panel and from fuse D (4) in the engine compartment fuse box.
Once the truck is OK, troubleshoot the trailer without it connected to the truck's wiring harness. I use a 12 volt battery and a couple of jumper wires. Connect the battery negative to the trailer's frame and touch the positive lead to each of the trailer's connection pins for running lights, turn signals and brakes one at a time. This will track down any problem with the trailer's turn signals, running lights or brakes.
This is easier than it sounds. You will probably find that fuse F or G blew.
Lou Braun
#4
07-01-2005, 08:23 PM
Originally Posted by Beast12
What do you mean about "wiring the trailer lights up on your dad's truck"?
If you have all good connections on the truck then it HAS to be the trailer. It could be a bad ground on the right side. Or, the bulb on the right could LOOK fine but not be. I would switch the left and right side bulbs on the trailer and go from there.
Good luck!
-Matt
If you have all good connections on the truck then it HAS to be the trailer. It could be a bad ground on the right side. Or, the bulb on the right could LOOK fine but not be. I would switch the left and right side bulbs on the trailer and go from there.
Good luck!
-Matt
My vote is that is still may be a fuse. Most people read the fuse box descriptions, and then selectively check the fuses they think will apply. This is the most sensible thing to do, but sometimes Ford's fuse boxes do not make sense. I would pull every fuse one at a time and check it, both under the hood and in the cab just to make sure there isn't another one blown somewhere.
Last edited by Franklin2; 07-01-2005 at 08:27 PM.
