2000ish ford f 150 trailer brake control module, heads up.

nickb2

Wrench. Diagnostic Tech.
Joined
Nov 22, 2008
Messages
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Location
St-Hyacinthe, Quebec, Canada
Make
ford
Model
f150
Year
2000 ish
Miles
200ish
Engine
5.4l
Ok guys, ran into a very specific problem on this one that ended up with me doing a wrong diagnosis.

This was another can bus mystery.

First off, truck came in, complaint was electric brake inop for trailer.

Ok, this should be easy enough. Nope.

First thing I do, get diagram, study wiring to get a gist of it and start testing. Fuses etc. No power to TBCM (trailer brake control module) fuse. SO I start there.

Find that BPP is not sending signal to PCM. So drag out scanner, find a few codes, one of which was very revealing. I cant remember the code, but it was a short to Vbat in the TBCM. Clear that and lo and behold, power is now restored to TBCM and now have brake signal.

Then proceed to diagnose the rest. I find that all is fine in the wiring and all is good also on the trailer.

So I then use my sherlock holmes theory that it must be the module itself.

Wrong.

This is where talking to a client is important. But with covid shyte, not so easy anymore.

Anyway, here is the heads up.

If the abs module has a code, it will disable the TBCM. Put a sensor on rear right, everything back to normal, and now I have a junkyard TBCM for sale.
 

nickb2

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of interest here, is I work in a shop that does trailer stuff among other things. So I went and saw the trailer guys, they said same thing as me. Must be the module.

No. The can bus would not let electric brake function on pedal apply, but would power blue wire if used gain manually.

This was most confusing to me. SO, I ask my foreman to call client. Did electric brake stop working lately or a long time ago

Client reports back, says it stopped working a while ago. I ask, did it stop working when you hooked it up to your other work trailer, he says no, it has been off for a while. I ask, why the abs light is on, he says it has been on for a year or so now. I ask, when was the last time you actually used the electric function, about a yrs or so ago.

Bingo, found it.

Moral of this story, always ask questions.

Cuz nobody in my shop knew that if a ABS code is stored, it will disable electric brake function. All the rest will work, gain, light back up etc.

So I hope this helps someone some day. Cuz I am not a ford tech. I am a all around tech and cannot know all this stuff by heart.
 

nickb2

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So, I then proceed to install a new sensor, find that brake lining are gone. Tone ring is damaged because client now remembers he had not enough money to fix that, so just let it go. Linings had tor out of back plate, broke the sensor and had also gouged the tone ring.

He said since this covid thing, not enough work to get his work truck done, cuz he has no work. Now he has work, and needs it running good.

So I completely believe him. I trust my work, and this was a shamble from get go cuz I for 1 did not have enough info and #2, I have NEVER seen that on any other truck before.

So, Now I know.

hence, my heads up :fixed:
 

billr

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You may not feel this way, but I say "good job"! It is an example of how tricky problems can be to diagnose, and it sounds like you did not charge the client for the un-needed module. The client should be very happy with your professionally-assiduous effort.

PS: If you really want to find a home for that module, you better post the P/N or exact year of F-150 it is for.
 

nickb2

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PS: If you really want to find a home for that module, you better post the P/N or exact year of F-150 it is for.
Thx billr for those kind words, and the module isnt for sale, that was just a end thread joke. A conclusion if you will.

Again, thx for those kind words
 

Mobile Dan

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Kentucky
This thread reminds me that there should be a Programming Guide that spells out "how it works" specifically for each code for each vehicle for each year plus notes for changes made during flash updates. Yep, auto repair can be tough!
 

jigfeett

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Good job, those issues derived from another issue do make for a big challenge.
 

nickb2

Wrench. Diagnostic Tech.
Joined
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Location
St-Hyacinthe, Quebec, Canada
and the module isnt for sale
I forgot to say, around here for 15yrs or so I have been doing business with this salvage yard. Nice and local no hassle, he will take it back, he knows we give him alot of volume.


there should be a Programming Guide that spells out "how it works" specifically for each code for each vehicle for each year plus notes for changes made during flash updates

FAT F ING CHANCE!!

 
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