Brake controller ground problem

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Oct 6, 2005 | 02:52 PM

therdt

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From: Colorado

Brake controller ground problem

I have a Prodigy brake controller installed in my 97 F250HD. The controller intermittently displays a "b9" code which equals a faulty ground. The truck was equipped with the factory wiring harness for the controller to plug in under the dash. I have confirmed that there is a good ground connection right at the trailer connector (extra line straight to the frame). Any body have thoughts on how to fix this?

'97 F250HD Crew 7.5L E40D

Oct 6, 2005 | 02:55 PM

therdt

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From: Colorado

Forgot to mention that the error code is present without a trailer connected, and when the trailer is connected the controller functions intermittantly. Thus I believe the problem to be isolated to the truck or the controller.

Oct 6, 2005 | 03:36 PM

alchymist

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From: Mifflin, PA

Is there a ground wire at the dash? Is it solid?

Oct 6, 2005 | 05:53 PM

therdt

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From: Colorado

I couldn't see up inside dash. Would it be a standard factory assembly practice to have a ground wire in a connector and then contact a chassis ground as close the connector as possible? I can't tell from schematics in the manuals where the wire would actually be attached to the chassis for ground

Oct 6, 2005 | 10:23 PM

Cowboy Brett

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From: Wickenburg, AZ

Did you buy the connector that plugs the Prodigy straight into the Factory harness, or did you use the Ford pigtail and solder/crimp onto the prodigy's pigtail?

If you "made" the harness like I did from the pigtail Ford gives you and the Pigtail Tekonsha gives you with the Prodigy, I would make sure you have good connections there. If you had a cold joint or you did not crimp that terminal down right, you could get a bad ground.

Are you still using the factory 7-pin round connector at the back of the truck? Perhaps if the connector was swapped out for something else or replaced for some other reason, the ground wire is not connected properly all the time to the appropriate pin at the truck side of the connection. If it is not the factory connector at the back or they didn't have those with that truck, my bet would be that you either have a loose screw inside the terminal block or a strand or two or wire touching the ground to something else in there (probably the electric brake circuit feed).

Oct 6, 2005 | 10:36 PM

Cowboy Brett

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From: Wickenburg, AZ

A small (ha!) addition for you....

You know, if you don't have a trailer connected to the controller, it should say "n.c" if you slide the manual lever or just have the decimal point when you hit the brakes.

Somewhere on the truck, you've got to have that brake controller output line shorting intermittently to ground.

If you just used that six-pin grey connector under the dash to hook up the controller, you should have good power and ground at the controller end. Now, I could be wrong, but if you had intermittant power to the controller iteslf, I would just expect the decimal point to flicker on and off or something silly like that. Besides, if it had bad power being fed to it, how would it be able to tell you a diagnostic code? I don't think it has any back-up battery built into it or anything like that. I think it is telling you that there is a fault in the controller output circuit.

Oct 7, 2005 | 10:34 AM

therdt

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From: Colorado

I used all the factory stuff, and the ford specific pigtail. I have disassembled the 7 pin connector at the bumper and confirmed that all connections are good and there is a solid ground there. thats a good point, if there was a intermittant short on the output and not the ground that might cause the error codes. the controller never goes dark so i don't think it ever loses power. thanks for the tip, i will trace the other lines instead of the grounds.