08 Trailer wiring ?

mkapp · 04-15-2008, 08:20 PM

Got an aftermarket hitch installed by uhaul, and it came wired with a 4-flat harness. The trailer that I commonly use (no brakes, just lights) is a 7-pin round, so I also bought a 4-flat to 7-round adapter. Everything worked great except the blinkers were going at a very high speed. Then it got dark, and with the headlights on and the brakes on, no blinkers worked - both sides just flashed like the emer. flashers were on. I went back to Uhaul and they tested their wiring and all is well (for the 4-flat). The problem stemmed from the adapter not being grounded separately. So I grounded it to the frame and now all the lights work, regardless of brake or headlights...but they still blink at a higher speed when the trailer is on. It drives me nuts! Anyone have any ideas? Is there a relay that needs to be in there, or is my wiring still not really correct?

hawkspringsfire · 04-16-2008, 12:51 AM

Watch this video it explains everything.

YouTube - Wiring Harness Install, Ford Escape Hybrid - etrailer.com

mkapp · 04-16-2008, 06:06 AM

Thanks! I will have to take off the taillights and make sure that everything is hooked up. I watched the Uhaul guy test all the wires coming off the 4-flat and they were all correct, but who knows.

mkapp · 04-16-2008, 05:38 PM

So I took off the taillights and crawled underneath to check out all the wiring from all angles. Everything appears to wired correctly, as done in the video. The fuse piece is connected to the battery, the other little unit is there, and all the wiring/grounds appear to be good. Like I mentioned, everything works, just flashes at Mach 1 when the 7 pin is plugged in. Is that just how it is? Anyone else have this issue?

jonmark1985 · 04-16-2008, 07:16 PM

check your trailer wiring out, you may have a short, clicking the flasher faster

mkapp · 04-16-2008, 08:28 PM

I thought about that. It's actually my father-in-laws trailer, and it works fine on his truck. He has a boat that I plugged into and it did the exact same thing too.

Maybe I am just paranoid, but I have a gut feeling that something is wrong. The silver lining is that all the blinkers and brake lights work.

Appreciate the replies. If you can think of anything else to check or try let me know. Am I the only one using a 7-round plug? Perhaps my issue is the norm, but others dont use the same plug?

Abusch · 05-10-2008, 04:14 AM

This used to be a common problem on older model vehicles, which may apply to your problem.
The flasher works on 'heat' which is created by the amount of power going through the flasher unit. The more power going through, the faster the flasher unit heats up, causing it to flash faster. If you continue to use the extra lights from the trailer on this flasher, it may eventually burn it out. The fix for this problem is simple. Go to Ford, or some other after market part supplier, and get a replacement flasher unit that is designated as 'Heavy Duty', this should fix your problem.