wiring help needed

[429CJ-3X2]

The left turn signal and brake light didn't work on the trailer I bought. The problem seems to be in the truck wiring as that terminal on the truck was dead. Wire doesn't seem to be live on the truck side of the trailer connection just before the terminal. I pulled the taillight and connected a wire there and ran it to the trailer connector. I left the original wire in place too. Thought it was fixed until I hooked to the trailer this morning and immediately blew the fuses to the left taillight and the flasher. Now I have no turn signals on either side of the truck without the trailer.

Replacing the fuses will fix the truck, but how should I run power to that terminal on the trailer hookup? Should I have disconnected the original wire from the taillight to the trailer connector? What other vehicle uses the same factory trailer wiring as a 2002 Sport Trac?

 

[429CJ-3X2]

I checked all the fuses, replaced a couple, but still no turn signals - either side. No 4 way flashers either. This is just the truck. The trailer is not hooked up. What did I screw up?

 

[scdix50]

Do you have brake lights on the truck? Do you have an after market wiring or factory. Some trailers have 4 bulb tail lights/2 stop/2 turn. Is the truck a 2 bulb or 4 bulb. Stop, turn & 4 way is controled thru the multi switch at steering wheel. You could have picked the wrong wire at the tail light and feed power back thru something. What does the back side of the trailer connector look like?

 

[429CJ-3X2]

Yes, I have brake lights. Factory wiring, which had probably never been used til now since I put the hitch on and the plug is still in the bumper. There was some corrosion in the terminals on the truck wiring, but this wire seems dead before the terminal. Truck has only 1 multifilament bulb for tail, stop and turn. The trailer has 2 bulbs each side - standard lights, nothing uncommon there. Until I added this extra wire, all the trailer lights worked except the left turn and left brake lights, which are the same bulb. I even tried a new light assembly on the trailer before I found no power to the one terminal on the truck.

A new flasher didn't help, so I'm thinking I killed the multifunction switch. Brake lights still work probably because I just hooked up the trailer and hit the turn signal to check it. Didn't touch the brakes while the trailer was hooked up. I wonder if I spliced in ahead of a relay I shouldn't have bypassed.

 

[scdix50]

Read your post, Still thinking and running things thru my head. If anyone has any ideas jump in. Lets get the truck fixed Then the trailer. I have seen trailer wiring done all wrong.

 

[429CJ-3X2]

Thanks for the bump. Getting the truck fixed is definitely the priority. Spent a couple of hours this morning at the salvage yard pulling a couple of multifunction switches, relays and factory trailer wiring pigtails. I don't think the problem is with the trailer. All the trailer wiring is factory. Once I get the Sport Trac working, I'll hook my Explorer to the trailer to see if the left brake and turn signal work with it.

 

[429CJ-3X2]

FIXED THE TURN SIGNALS ON THE TRUCK!!!! I rechecked all the fuses again and found a bad one I missed yesterday in the bright sunlight. The fuse for the flasher unit was blown. Makes sense.

FYI - other than the flasher unit, the rest of the relays in the aux box 2 under the dash are all the same. And there are 2 more in the main fuse box under the hood just like them, and much easier to get to if you're pulling them out at the salvage yard. Wish I had known that several hours ago! Pt # F57B-14B192-AA.

Now to solve the trailer connection issue.

 

[scdix50]

Thats great. Is the trailer new or used. Go to etrailer.com & look at the wiring codes. I have seen new trailers with wires crossed and colors switched. If they are crossed you will get a feed back into your truck.

 

[429CJ-3X2]

The trailer is used. I've towed it 260 miles already and the only issue is the left turn and brake light. Just hooked it to my Explorer and the right side works like it should, but both sides flashed when I signaled left. Don't think that's due to a problem with the Explorer, but trailer wiring seems original. May have to rewire it anyway. Someday. Not a priority right now since most everything works right.

Still have to get power to the 1 terminal on the truck side.

 

[scdix50]

#1 should be ground. Trying to post this wire code as a PIA

 

[429CJ-3X2]

Sorry, I didn't mean the #1 terminal, but I can see how it was interpreted that way. I meant the 1 terminal of the 3 that should have power but doesn't. The terminal with no power is the yellow wire which should feed the left turn and brake lights.

As I was dealing with the other problem I discovered 2 bulbs that were burned out - the reverse light and the front turn signal on the left side. I wouldn't think the front signal being out would cause the trailer light to not work.

Thanks for the help.

 

[429CJ-3X2]

Fixed it!

Finally got this fixed!! There were 2 problems.
1) The wire from the taillight to the pigtail on the truck was dead. I ran a new wire from the taillight to the pigtail. Cut and capped the old wire.

2) I rewired the left side of the trailer starting at the back. Found the problem when I got to the pigtail on the trailer. I didn't start there because the guy I bought the trailer from said he'd had no problems. Anyway someone wired a new pigtail wrong. They had connected the white ground wire to the faded yellow wire, and hooked the new yellow (power) wire to a new wire which they grounded to the trailer frame. No wonder it blew fuses.

Lights all work like they're supposed to now.

 

[scdix50]

Great, Happy motoring