Factory Tow Package Problem Solved
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Member
Joined: Sep 2004
Posts: 10
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From: Alabama
Factory Tow Package Problem Solved
1999 F-150 with Factory Tow.
I installed the factory relay (space 201 in the underhood box) for trailer running lights.
Turned the switch on and the lights worked. Turned it off and they were still on. Unplugged the relay and they went off. Repeated with the same results.
I saw hundreds of $$ in diagnostic fees on the way, but I looked under the bed and saw a bright "new" white wire going to the trailer connector. I snipped it and the lights worked right.
It appears that the first owner - or his trailer dealer - couldn't get power at the factory plug, so they just jumped over from a taillight wire to the trailer running light wire.
Once I tried to use the relayed feed, the relay got power and locked itself down until it was unplugged.
This relay serves a good purpose in taking the trailer running light load off the truck's parking light circuitry. It also prevents a short in the trailer wiring from killing the truck lights. But I wonder how many trailer mechanics don't know it's there and take the easy way like this one?
I installed the factory relay (space 201 in the underhood box) for trailer running lights.
Turned the switch on and the lights worked. Turned it off and they were still on. Unplugged the relay and they went off. Repeated with the same results.
I saw hundreds of $$ in diagnostic fees on the way, but I looked under the bed and saw a bright "new" white wire going to the trailer connector. I snipped it and the lights worked right.
It appears that the first owner - or his trailer dealer - couldn't get power at the factory plug, so they just jumped over from a taillight wire to the trailer running light wire.
Once I tried to use the relayed feed, the relay got power and locked itself down until it was unplugged.
This relay serves a good purpose in taking the trailer running light load off the truck's parking light circuitry. It also prevents a short in the trailer wiring from killing the truck lights. But I wonder how many trailer mechanics don't know it's there and take the easy way like this one?
Senior Member
Joined: Jul 2004
Posts: 6,200
Likes: 39
From: Easton, Pa.
I am just getting ready to install the 7 pin combination factory tow wire harness on my 02 Screw.
Installed the missing relay and checked for all the fuses for being inplace.
One relay for trailer back-up lites, I also find out, will lock up the trailer brakes trying to move a trailer in reverse, on a hitch sensed loading configuration when this relay is in place.
My final controller will be the Prodigy unit that should not be affected by the back-up lite operation should it be used.
Wire info seems to be hard to come buy.
Will report later about how it goes in addition to a trans cooler installation.
Installed the missing relay and checked for all the fuses for being inplace.
One relay for trailer back-up lites, I also find out, will lock up the trailer brakes trying to move a trailer in reverse, on a hitch sensed loading configuration when this relay is in place.
My final controller will be the Prodigy unit that should not be affected by the back-up lite operation should it be used.
Wire info seems to be hard to come buy.
Will report later about how it goes in addition to a trans cooler installation.
Thread Starter
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Member
Joined: Sep 2004
Posts: 10
Likes: 0
From: Alabama
Factory Tow Package
The backup circuit is intended to lock OUT "surge brakes" when backing up. I guess this makes it possible to back up an incline. It won't affect our normal electric trailer brakes. But you can use this circuit if you want backup lights on your trailer.
I have the Prodigy. Its inertia and "hold" work in reverse as well as forward. Bought it from RJay's over the Internet. I think it was like $106 including the shipping. They upgraded shipping to second day at no charge. Also bought the Ford harness for about $10. It plugs straight into the gray connector under the dash.
www.etrailer.com/faq/wiring.asp will show the pin configuration for the 7-way connectors. The colors won't agree with the Ford harness, but the pins agree with the F-150 factory connector. I just installed a 7-pin on the motorhome using this as a guide.
I have the Prodigy. Its inertia and "hold" work in reverse as well as forward. Bought it from RJay's over the Internet. I think it was like $106 including the shipping. They upgraded shipping to second day at no charge. Also bought the Ford harness for about $10. It plugs straight into the gray connector under the dash.
www.etrailer.com/faq/wiring.asp will show the pin configuration for the 7-way connectors. The colors won't agree with the Ford harness, but the pins agree with the F-150 factory connector. I just installed a 7-pin on the motorhome using this as a guide.
Senior Member
Joined: Mar 2001
Posts: 3,248
Likes: 2
From: Rochester, NY, USA
One small correction. The blue wire is not intended to lock out "surge brakes." It's instended to lock out disk brakes used on a surge brake system. With drum brakes on a surge type system, you do not need this feature. That's why disk / surge brake equipped trailers have a "flat 5" connector and drum / surge brake equipped trailers have the "flat 4." Disk brakes are so much more effective that the slight actuation you get when backing up - which isn't enough to stop a trailer with drums - will stop everything cold with disks. The blue wire energizes a solenoid which blocks the brake line.