First off thank you & everyone else for your input.
Disconnected the 2 wires, no difference.
Drifted this thing back several times hoping the adjusters may even the adjustment out. The rear brake did not grab.
Just had the oil changed & the shop pulled the rear drums. Did not find anything other than brake dust.

 

Correct me if I'm wrong but there should be a fuse for the entire ABS system.

 

I forgot to mention that when the 2 connectors are hooked up to the RWAL module the brake light stays on. When disconnected it is off.

 

That’s because the RWAL module is tied into the brake warning indicator circuit. In the event of module malfunction or failure, the red brake indicator will turn on.

The top (blue) connector in your pic is the one that has the primary circuits.

Unplug it and check the following:

Black wire - ground
Brown/white wire - battery Voltage key on
orange/black wire - battery voltage at all times

If these circuits prove good, and the connector terminals are in good condition, the module needs to be replaced.

That said, given that the wheel isn’t locking up in reverse, I suspect the shoes are in the wrong position. I understand the shop told you they didn’t find anything but drum brakes are not as widely used as they used to be and many techs don’t know to look at the length of the shoe linings.

See below pic - the shoe with the shorter lining must be positioned in the front of the axle (marked them with red to highlight the difference). Because of how drum brakes work, if it’s positioned behind the axle, it can cause wheel lockup even if everything else is installed correctly. And given that letting off the brake resolves the problem, it’s a likely culprit.

​​​​I recommend verifying this yourself.

 

Being how the brake light stays on doesn't that indicate the module is bad? Can I just disconnect the RWAL module and leave it disconnected? Anti lock has not worked for a long time. I will check out the brake shoes positions.

 

Technically no - the light indicates a problem with the RWAL system that’s causing it to be disabled.

However, it wouldn’t surprise me if the module is bad, so that’s the reason to verify the power and ground circuits.

It’s your decision - leaving it unplugged is an option if that’s what you want to do.

 

I did check the wiring as you suggested and those circuits were ok. I just unhooked the module.
Will look at the shoes when I get a chance. Thanks for your help.

 

An update on this thread. I had this truck to the 4th garage for this problem. This garage turned the brake drums, installed OEM brake shoes, which the mechanic insisted on OEM shoes, and installed a new left side emergency cable. Right now the brakes are working great. Hope they keep working.
My question is he was adamant about using the OEM shoes saying he thought that was the problem. In what ways would they be different than aftermarket shoes. In all the times the shoes have been changed they were always aftermarket. This time they are OEM & they are working great????

 

Thanks for the update - glad you got it sorted out.

I can only speculate on the insistence of using OEM brake shoes - there’s too many factors to be certain about the decision. I’ve used aftermarket shoes on several of these trucks and I’ve never had problems with them, so you may just have to ask for more details from the mechanic.

 

I do know this mechanic pretty well & he is pretty hard core against aftermarket stuff, even though he knows most OEM stuff is not made in the USA. However, whatever shoes he put on the truck are working better than all of the other that have been installed. Just hope it keeps working well as this problem has been going on for quite a while. I am curious as to why this would have made a difference? He did install a new left side emergency brake cable which had been replaced not too long ago. Could this have been the problem?