Fixing RABS ground connection

[rreegg]

The “rear antilock” light has been on in the truck since I got it. The brakes should be bled but the pedal is still soft.

My thinking is the RABS May be responsible for the soft pedal.

Got the error code from the RABS unit and it’s fault #2 - Open Isolate Circuit. I’ve found a rabs diagnostic page (attached) from ford and believe the ground on the rabs unit harness to be bad.

Can I just cut the ground wire at the harness and ground it to the frame? If it doesn’t work can always splice it back but would like to save the hassle.

Grounding has given me some confusion in the past so not sure if this is a valid way to ground the rabs unit or if it needs to be grounded further upstream from where the wire originates

 

[IDIBRONCO]

The “rear antilock” light has been on in the truck since I got it.

I thought that was just normal on these trucks. They all seem to have that lit up.

 

[Nero]

Mine works lol

The ground wire is either between the battery and the core support on the left, or on the right. Ive seen it in both places. On my 1990 it is behind thr drivers battery and the connector likes to come apart at times.

 

[KansasIDI]

It appears that F Super Duty trucks weren’t equipped with any kind of ABS… I wonder why…

Ah well, one less thing to go wrong.

I couldn’t imagine not having that truck now, it’s been a godsend… definitely my favorite.


Do the RABS equipped trucks have the proportioning valve that adjusts the brakes based off of load, like the bullnose trucks and F Super Duty trucks?

Very pointless to have that sensor on a F Super Duty with the heavy spring package, 18k on a bumper pull doesn’t make it squat at all… like at all… zero… but the brakes still handle the load with amazing ease… big disc brakes all the way around and hydroboost makes a difference…

 

[Nero]

I don't think so. The few times mine have activated they just modulate releasing the rear brakes in a sliding event. So rapid on/off

 

[rreegg]

Yahtzee fixed the light haha. Yep @Nero was spot on it was the plain black wire on the passenger side between battery and fender.

Was able to check continuity between candidate wires at the firewall and at the RABS harness. What’s odd is the wire switches from black/white tracer to plain black somewhere in the engine compartment. The harness doesn’t appear to be tampered with but was open short regardless. Oh well.

Just snipped it and bolted it to firewall.

Didn’t really care about the light being on and brakes don’t appear to be any better, or negligible so if that.

Guess gonna adjust rear drums and bleed rabs again

 

[Nero]

Hah, crazy how one innocent looking wire causes so many people to say, f it I'm gonna delete the RABS. Glad you got yours working. I'm definitely a fan of keeping it, especially since its saved my bacon a few times.