Low brake volts @ 7 pin connector - only with brake pedal

Question

Hi... I have a 2012 F350. I'm having problems with the 7 pin connector, specifically the brakes. With my factory integrated brake controller set to 10 (max), the brake pedal gives me 2-6.5 volts at the trucks 7 pin connector at the bumper (the voltage changes around). As soon as I squeeze the manual over-ride I get a full 12 volts at 7 pin connector. I'm testing this with the truck actually running.

As a result the brakes on the trailer aren't engaging properly and I'm reluctant to drive it in the mountain. I was supposed to leave tomorrow though :(

Any thoughts? Are there any fuses relays I should be checking?

I did read one post that said they heard it could be a problem with the pressure transducer. Does this make sense and is it easy to swap out?

I appreciate everyone's thoughts
Dan

home_skillet · Answer

You won't get full voltage when applying the brakes at a stop in park.Hook up the volt meter, go drive the truck and monitor the voltage.

dsulliva · Answer

Thanks for the suggestion. Dumb question, how do I do this? Currently I have the probes of a volt meter stuck into the 7 pin connector at the bumper. Do I sit in the box while someone drives around or is there a better way?

Should have also mentioned a few more details:
- I'm getting no error messages on the message centre, brake controller recognizes the truck as connected
- I used a 7 pin tester and was getting similar results (brake light was off or dim with brake pedal, bright with manual over-ride)
- When driving pedal would apply little pressure to trailer brakes but manual over-ride would lock up the tires
- Trailer brakes worked good when I put it away 2 weeks ago (that always seems to be the case though)

dsulliva · Answer

OK... I think I figured it out. It seems the cord from the trailer was slopping around in the receptacle on the truck. When the receptacle cover put that little extra pressure on the cord it was creating a flaky connection. Phew. Nothing big. A little electrical tap on the cord to tighten it up in the receptacle. All is good...

Thanks
Dan

sport45 · Answer

I believe it's an inertial controller. When the rig is stationary the it won't send 12V to the trailer brakes because it knows they don't need it.

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Low brake volts @ 7 pin connector - only with brake pedal

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