Towing my new fifth wheel home today I noticed that the ABS light had come on about 250 miles into the trip. We were stopping at a rest area so I took some time to check fuses and everything appears OK. I also noticed that the integrated trailer brake controller display showed the trailer connected, brake lights worked fine, but stepping on the brake pedal didn't cause the brake controller display to show any bars as if the trailer brakes weren't working. Using the manual trailer brake levers (squeeze them together) would actuate the trailer brakes just fine. Started down the road and the ABS light went out and then pressing the brake pedal caused the trailer brake controller to display the bars showing that the trailer brakes were working fine and I could tell that brakes were once again working. A little later the ABS light came back on and sure enough...the trailer brakes stopped working with the brake pedal. I did notice a few times that if I really pressed hard on the brake pedal that I'd see one or two bars on the controller display.

Any ideas?

thanks

 

Do you have a bad connection at the 3 ABS sensors or bad ABS sensors?

Check that first.. and if it checks.. then go further.

2 sensors are at front wheels, 1 at the rear in the "pumpkin" at the top.

Follow directions below to clean contacts.. check sensors.. see if that can get the ABS out of failure mode.

 

Thanks, Gear...I found several TSBs regarding this and a few posts where folks had similar issues and the VSS needed to be replaced. I'll climb under it tonight and take a peek. I may just order a VSS to install as well.

thank you

 

While you are at it... check the connections into the VSS

Post the TSB numbers or the TSBs if you can.. thanks.

 

Here's one that explains the diags for ABS light on, although it doesn't mention trailer brakes with the integrated brake controller I found a post on thedieselstop that had the same symptoms on an 06 and a VSS replacement cured it

06-7-6***ABS LIGHT ON AND POSSIBLE DTCS C1175, C1236, P0500, P0503

Link to the posts on the diesel stop...look at the bottom and find Cody315's posts

 

Here is the real interesting part from that TSB:




For quite some time, I have been thinking that Ford has got to greatly improve their electricals / wiring / electronics.

 

Yep...I'm going to go thru and put dielectric grease in as many connectors as I can access. I was thinking of selling this truck to get an 08 or 09 V10, but I think we'll just hang on to it for a while. I put about $1000 a year into it which is still wayyyyyy under what a used truck payment would cost.

 

Here's an update...ABS light is on...no codes in the ECU. Normal? Expected behavior?

 

Not all code readers read the ABS boxes...

You need one that specifically say it reads those codes.


If you want to be annoyed...

The ones that read Airbag codes.. extra $$$

Read extended Ford codes $$$$

Read diesel codes $$$$$

Need I go on?

 

LOL...makes sense!

 

I know that the original post is 10 years old. But did you ever solve the problem? Our F450 is performing exactly the same way. Except, like yours, our problem started out intermittently and now our ABS light is always on.