I just bought a 97 AWD and am trying to sort out a periodic problem with the rear brakes locking up. It only seems to do this when the van has been sitting for several hours. If you stop and start 3, or 4 times (on dry pavement vs the snow we have here) it seems to stop doing it.

I searched other posts and found something about cleaning a pin in the modulator...no idea where those are...however that post said his BRAKE light and ABS light also kept coming on ... I don't have that problem.

Thought that this was an emergency brake issue, but don't think so, it works well and seems to be releasing fine.

Something with traction control/ABS system maybe...?

Any pointers are appreciated.

 

Still sorting this out. I looked for a gold colored RABS "box" which I thought (from another post) was supposed to be located on the drivers side on the transmission hump, up under the dash. I didn't find anything there. I did find a black box about 4" x 6" mounted directly under the ash tray which I think might be it.

Checked and (if it is the RABS box) the connector is plugged in. I don't get any ABS or BRAKE warning lights on my dash at all.

The other thing I have noticed is that when the van is first started and you apply the brakes, there is a loud clicking sound that seems to come from inside the dash (or perhaps in the engine compartment) on the passenger side. It's definately NOT from the master cylinder. The click (or more accurately "clunk") happens immediately just as you start to let off the brake pedal. If you keep pumping the pedal, this clunk happens for maybe 5, or 6 times then mysteriously stops.

I should mention that this van used to be city owned and (believe it or not) was rigged up as a small ambulance. So it has an assortment of wires and relays and switches for all the associated lights, bells and whistles that have since been removed. I mention this because perhaps this "clunk" is the sound of a (big) relay somewhere that has something to do with the ambulance conversion....I just don't know. I'll try to locate the source of the clunk when I can get a buddy over and look under the hood while trying the brakes.

Anybody out there with other ideas? Is my RABS box "pooched?"

 

Do you find that the brakes lock up worse when they are cool and it's damp out?
That used to be quite common.
Quite often just cleaning the rear brakes will help. You can remove the adjuster plug in the backing plate and flush the dust out with a garden hose aimed into the adjuster hole.
Another thing that helps is chamfering the ends of the shoes in to about 1/4-1/2" from the end.
If neither of those helps then you may have to replace the shoes.
Also make sure the brakes are adjusted properly and that there is no oil on them from leaky axle seals. Oil on brake shoes makes them lock up bad.

 

Thanks for the tips, I'll try and pull the wheels off this weekend to check the shoes for oil.

It's been cold and damp here this week so ... maybe yeah that's an issue too.

I'll let you know what I find.

 

It's raining pretty hard here in CA. If my van sits overnight, the rear brakes would lock up on me the first one or two times I step on it. So I guess it's normal, as long as it doens't do it all the time. In dry weather, it never happens.

 

canadaler
I have had a similar problem and the pin that holds the brake shoe on the hub was gone.The shoe can tip side ways and bind up.Look on back of hub and see if you can see the backs of these pins if not that could be your problem.It will probley back up and get tight when you go ahead. Had to put a small bolt with washers & nut rather than use old pin.

 

I have the problem when it has been raining overnight. If I apply the parking brake overnight (shoes pressed against the drums) the rear brakes don't lock up so easily. Perhaps by applying the parking brake, water doesn't get between the shoes and the drum.

 

Problem solved...there had been a brake job done on this at some point and somebody went "cheap" and didn't buy the $10 spring kit for it. The rubber plugs that go in the holes for the "self adjusters" were both missing and the adjusters were rusted solid.

Had a *&%^ of a time getting the drums off, but after I finally did, I put a new spring kit in each wheel, freed up the adjusters (required a torch for one) re-assembled and things are much better now.

Appreciate the suggestions from everyone...thanks.