My rabs activated last night for the first time ever on the ice, and it blew the #13 fuse. Put a new one in, and as soon as I hit the brakes again, this time, no rabs activated as far as I could tell but it blew #13 again. I took out the other abs fuse, the 30 amp, and put another in #13 and was able to make it home with brake lights and no shift interlock. Got home, put the 30 amp back in and drove down the road. Got it up to about 40-45 and slammed on it, blew #13 again. My cruise has always worked, but I'm not sure if that is related or not. Checked the fluid, and it was a little low, but nothing to worry about, I added more though. Anyone have any ideas? I need my rabs since we've gotten pouned with snow, and now it's solid ice. Thanks!

 

https://www.ford-trucks.com/forums/3...ellow-red.html Have a read here. Probably best to check for trouble codes. Ignore anything in thread about full abs. Check things for RABS only.
Good luck and remember RABS only work properly if rear brakes in good condition and properly adjusted up.

 

Thanks, but the rabs link in that post is no longer available. My rear brakes are fine condition and adjusted properly. Since this is the first time the rabs activated, my thought is that it is a problem with the system. My first thought is the sensor on the axle. When the light was on, it would flash 15 short, and 1 long. I thought that indicates a normal condition. But that doesnt make any sense since it's blowing the fuse.

 

See what you mean about the pages no longer there.
Maybe navigate from raybestos .com to the tutorial on rabs.
Flashing abs light without grounding the diagnostic connector just indicates a blown fuse.
Your RABS ECM should be behind the glovebox, check that no cracked/frayed wiring.
RABS Hydraulic Control Module on left side frame rail, check for rayed/cracked/damaged wiring from it, from rear VSS and along frame rail.

 

Checked all the wiring last night from vss forward, all looked good. Thought it might be the trailer wiring since I have two, one in the bed and one at the hitch, nope all is good there too. I'll check the ecm tonight, but just seems strange that all of a sudden this happens. Could the ecm be bad? Would a bad vss cause it to freak out and blow the fuse? I know the ecm is really expensive and not something I can do right now. I also read that it could be the pressure switch on the master cylinder, how can I test this, by unplugging it, and see if it still blows the fuse when rabs activates?

 

The Powertrain Control Module (PCM) does not control the RABS hydraulic actuator located on the driver side frame rail. The RABS controller mounted behind the passenger side glovebox performs this function.

Fuse 13, which should be a 15 AMP fuse, sends power to the Brake On/Off (BOO) switch on the brake pedal assembly then onto the RABS controller.

It also supplies power to the Brake Pressure Switch on the Master Cylinder. This problematic switch is the cause of many vehicle fires and a massive recall. If your truck has not had the inline fuse harness installed then you have not had the recall performed and your truck is now a fire hazard. Pull the connector leading to the Brake Pressure switch ASAP, if not sooner.

Your fuse blowing issue may be a bad BPS switch. Applying electrical current to brake fluid causes fires...

On the other hand the BPS is always closed until you apply pressure to it, then it opens. But the membrane is known to rupture which allows brake fluid to come into contact with brake fluid. Perhaps the membrane leaks only under pressure? Might be a moot point if the recall has been performed.

 

The harness looks like it has an inline blade fuse taped to it. Has a tag on it that says it contains an unserviceable fuse and if its blown to replace with harness number blah blah blah. If this switch was bad, wouldn't cruise not work?

Sorry, used the wrong acronym for the rabs electrical control module. I wasn't referring to the hydraulic one on the frame rail. Seems like a circuit is overloading some how obviously since the fuse is blowing. I guess the only test I can do is make it happen again and read the codes while the truck is running since it doesn't store codes. Could a bad vss cause it to blow the fuse? That doesn't make sense. I could see rabs not working but not blowing the fuse because of it being bad. Is there a test I can do on the pressure switch?

Btw, I'm not new to turning wrenches, just uneducated on abs systems. So you can be as technical as needed. I actually prefer that.

Thanks guys!

 

No a bad VSS will not cause a problem with Fuse 13. A bad BPS switch would definitely blow the fuse on the inline harness/fuse. That is the reason why Ford installed it. Although the early recall harnesses were wired wrong.....the smaller fuse was effectively bypassed.

You could try unplugging the BPS then step on the brake, if the fuse still opens then you know that circuit is okay.

One other item Fuse 13 supplies is the Keep Alive Power for the RABS controller. I would start disconnecting the BPS, then the RABS controller until the fuse quits opening up. Perhaps a shorted wire between the BOO switch and the RABS controller? Or use a meter set to ohms, pull the fuse before doing so!