Brake problem/RABS I issue?

For a little background on this problem:

http://www.oilburners.net/forums/showthread.php?t=39738

Here's the deal: I replaced the vacuum pump as was recommended in the above thread, but the 'Rear Antilock' and 'Brake' lights have come on since. I've put about 120 miles on it and they've only come on twice in that time, whereas before I replaced the vacuum pump the lights would come on after the truck had been running for five (or less) minutes. However, I hadn't noticed the brakes locking up like they had been.
A couple of days ago, I took the truck out on a 15-mile trip to get the engine warmed up. Towards the end of it, I decided to brake fairly hard to see if the brake lock-up problem had been solved. It had not.
Yesterday I went down to the dump to get rid of a load of garbage. I pulled in, shut off the truck, unloaded the garbage and got back in the truck. I started it up, put it in gear and released the clutch. The truck acted like the parking brake was on. It wasn't and the 'Brake' light on the dash was not lit up. I pressed down on the parking brake pedal and there was very little resistance. I released the parking brake, put it in gear and again tried to leave. It still acted like the parking brake was engaged. I left with the brakes dragging. After a couple of miles, they had released and were not dragging.
This is leading me to believe that there's something going on with rear brakes. I read my Chilton's and reviewed the procedure for obtaining codes from the RABS I system. (I'm pretty sure that's the system my truck has, I couldn't find a control module behind the glove box like the RABS II system.) I grounded the diagnostic connector with the ignition in the RUN position and the 'Rear Antilock' light came on while my jumper cable was connected to ground, but as soon as I released it, the light went off. According to Chilton's, if you ground the connector for 1-2 seconds, the 'Rear Antilock' light should start flashing in a sequence to allow for a reading of the trouble code.
One odd thing to note about the RABS I system in my truck: according to Chilton's, the diagnostic connector should have two halves that you need to take apart in order to ground the black/orange wire. My truck doesn't have two halves, it's just got the one black/orange wire hanging free (with a plastic connector half protecting the bare metal). I searched around and couldn't find the other half.
Does anyone have any experience or input that might be helpful?

Rears locking up like that and then drifting back I would suspect rear rubber brake hose. What happens is it will get a split in the inside and act as a check valve, trapping the pressurized fluid and keeping the brakes in the rear on even though you released the pedal.

87crewdually said:

Rears locking up like that and then drifting back I would suspect rear rubber brake hose. What happens is it will get a split in the inside and act as a check valve, trapping the pressurized fluid and keeping the brakes in the rear on even though you released the pedal.

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Hmm... that makes sense. Is there any way to tell from the outside that the rubber lines have gone bad?

Anybody else have any other ideas? I've been thinking about tearing into the rear drum brake assemblies and would like to avoid it if at all possible.

No real way to tell until you remove them. A guy I worked with was having brake problems and replaced all the front brake hardware on the front wheels. Still had the problem, so he took it in (didn't talk to me till after it was fixed...) and they found the lines were bad. He brought the old lines in, and they looked just fine, but were bad enought you could not blow air thru the lines....

No real way of telling a hose has collapsed internally, that's the bad thing about that type of failure...

take it to ntb or pepboys let them throw parts at it till they fix it then tell them they didnt need to replace all that and only get billed for the one that fixed it

BrandonMag said:

Hmm... that makes sense. Is there any way to tell from the outside that the rubber lines have gone bad?

Anybody else have any other ideas? I've been thinking about tearing into the rear drum brake assemblies and would like to avoid it if at all possible.

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With the bend of the hose and 20 years of flexing the hose it deserves to be replaced anyway, after all it's affordable.

87crewdually said:

With the bend of the hose and 20 years of flexing the hose it deserves to be replaced anyway, after all it's affordable.

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Good point. I'll be replacing these hoses as soon as I can.

I replaced the rear brake hose, no changes. The rear brakes were still dragging.
I rip into the rear drums and find that the sheathing on the parking brake cables has gotten old and chipped off, binding up the cables and causing the rear brake shoes to not release completely. I go to NAPA, buy the cables for just over $40, and install them.
I decide to take it for a quick trip, quite sure I've fixed the problem. I brake fairly hard a couple of times, no problems. The third time I brake hard, however, I notice the dreaded dragging brakes are back. I'm about halfway through a 15-mile test drive. Once I get about a mile from my house, I can see a cloud of smoke emitting from the right rear wheel.
I pull over, get a snootfull of that great burning brake smell, and wait to let it cool down. After a couple of minutes, I try to move it. NOTHING. It's like the rear brake shoe is welded to the drum. After about 20 minutes, I'm able to get it home. I re-rip apart the driver's side drum, and the front shoe comes out in chunks.
At this point, I say "F%$# it" and take it to the mechanic. We'll see what he says in a couple of days.

With it isolated now to the one wheel, the only thing left that I didn't see if you replaced is the wheel cylinder.

Wheel cylinder is a possibility, but I'm thinking also the backing plate - the areas on it where the shoes ride on (being pulled by the retaining springs) get grooves worn into them with time, which causes the shoes to stop moving smoothly in and out of the drum - the solution to that is either replace the backing plate, or weld up the grooves shut and then grind the weld down smooth so you have a new surface for the shoe to ride on...

LCAM-01XA said:

Wheel cylinder is a possibility, but I'm thinking also the backing plate - the areas on it where the shoes ride on (being pulled by the retaining springs) get grooves worn into them with time, which causes the shoes to stop moving smoothly in and out of the drum - the solution to that is either replace the backing plate, or weld up the grooves shut and then grind the weld down smooth

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Had a forklift do this a few years ago. The shoe had worn a nice grove in the backing plate, and allowed it to sit at an angle in the drum and get stuck after a brake application...

Normally, I'd fix the brake problem myself. But I just got called out of the hall to a windfarm in Arlington, OR on Tuesday. I was supposed to be there Wednesday and ended up not being able to show up until Thursday because of this brake problem.
I talked to the mechanic yesterday, and he replaced both wheel cylinders, the shoes, turned the drums and readjusted the parking brake. He took it for a long test drive. No problems noticed.
My dad picked it up for me today. He didn't notice any problems either.
It sounds like it's fixed!

Glad things are fixed finally. I know how difficult it is when you try everything possible to fix something. Then give it to someone else and they have no problem repairing it. I don't get upset but I do learn for things like that....

icanfixall said:

Glad things are fixed finally. I know how difficult it is when you try everything possible to fix something. Then give it to someone else and they have no problem repairing it. I don't get upset but I do learn for things like that....

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He didn't try everything.............wheel cylinders sound to be the culprit. Times like this is why shops brake jobs can cost over $1000 because they replace everything to eliminate call backs with problems. Those 29.95 brake jobs are a thing of the past in the real world.