ABS trouble on a 1991 Cutlass Supreme

[peeeot]

Hello,

 

I bought a 1991 Cutlass Supreme convertible a month or so ago, and I was told the ABS light was on. The previous owner had covered the light with a piece of black duct tape so she didn't have to look at it. When I uncovered it, I discovered that not only was it on, it was flashing! Further analysis of the brake system has revealed several problem symptoms, all associated with the rear disks (which I gather is a frequent thing). First, the parking break engages more securely on the driver side than the passenger side. Second, the passenger side brake releases more fully from the rotor than does the driver side. Third, neither side operates UNLESS the ignition key is on, such that the ABS power assist operates. Fourth, a small amount of brake fluid seeps (and sometimes squirts) from a hole in a sort of cap screw in the rear proportioning valve, next to the fuel filter.

 

At this point, I suspect that ALL of these symptoms are linked to and caused by a sticking or otherwise faulty rear proportioning valve. Apparently this particular ABS system was not used for long, nor was it ordered very often, because the part is rare and relatively expensive. What's more, I'm not aware of ANY later model cars that use integral ABS instead of the traditional vacuum booster with a separate ABS module.

 

Anyway, I'd like to know if anyone else has encountered this problem, and what they did to take care of it. I'm baffled as to why the valve at the rear would have a hole in it that could leak, but it was clearly there from the factory. Just not supposed to leak.

 

I'd also like to know whether it would be a good idea to go ahead and do the rear disk conversion that the creator of this site did. I'd like to keep things as stock as possible for convenience but if these brakes will be a constant source of trouble and the conversion is cheap, I'd consider it. Thanks!!

[bigshynepo]

AFAIK, It's inevitable to have to do conversions on all four break assemblies due to the faulty nature of the system from the factory. I had to on my 88 and 89, my 95 has also had rear break work on it.

 

Lets see some pictures of this Cutty!!!!! Members Rides is a nice place to introduce yourself.

[herb427sc]

Is this a PMIII (PowerMaster3) brake system???

[White93z34]

it sounds like it, however from what i read it has gotten FAR more easy and cheep to repair these systems in the past year or so.

 

i know next to nothing about PMIII but someone will surely chime in about it.

[peeeot]

I don't know what model ABS system it is. This is the hydraulic unit for it:

 

http://www.partsamerica.com/ProductDetail.aspx?mfrcode=RAY&mfrpartnumber=ABS540087&parttype=1395&ptset=A

 

it has a pressurized gas reservoir, an electric fluid pump, a fluid reservoir, the master cylinder, and who knows what else all in one assembly. There appear to be separate brake lines for each front wheel and a single line for both rears, with a proportioning valve for the rears.

[Lee]

Welcome to the PMlll misery.

 

My rear proportioner valve started leaking this spring. New part was $204 = tax. I was able to get one off this board much cheaper. J/Y would be a source also.

 

Yeah the factory put some kind of odd nut on the beveled part of the proportioner block with a little rubber plug in it. It rots! The GM Manual says no repair/replace only. Dealer part only.

 

As for the rest of the troubles.....you'll be fortunate if the valve replacement fixes them. Keeping my car instead of junking it all depends on the PMlll continuing to get by. My biggest fear.

[peeeot]

Wow, I think you've confirmed my worst fears about this system (and accordingly my purchase of this car). It almost makes me consider swapping for a standard power brake setup, but that wouldn't be a simple affair, in any respect. Nor cheap. It's a relief to know that someone else has experienced this though.

 

I was taunted by a $30 part listing on oehq.com for that valve, only to look more closely and realize that it wasn't available and that the replacement part that IS avialable is $137. Same AC Delco part number as what the dealer provides for the $204 part, #88927272. I don't get why the same part can cost $100 different. Oh well.

 

Were you able to get your replacement valve for cheaper than $137? How did you get it? Also, what's "J/Y"?

 

That's ridiculous about them using a rubber plug. Why couldn't it simply be removed and replaced with a solid metal cap screw? Why didn't they do that in the first place?

 

I hope this car doesn't prove to be a headache like ALL of the other computer-controlled, fuel-injected, post-70s cars I've owned.

[Cueman]

"J/Y" = Junk Yard, great/only place for some parts off of our vehicles!

[peeeot]

Haha, seems like I should have been able to figure that one out.

 

I checked with several local yards. None of the W-bodies around have ABS.

[Crazy K]

vaccum booster conversion is the only way to go! wanna sell it?

[Lee]

The vacuum coversion is very in depth. I'd just find a used proportioner valve and get it switched. That may be all that is happening. At the junk yards you want to look for that odd brake fluid resivior cap. They had them in Bonnivilles and probably Rivieras. Not sure they'd have the same rear proportioner valve but maybe. I think you may have best luck with Regals in the w-body family. Mine is only a custom and it has ABS. Look for 88 - 91. Regals were only 2 doors from 88 - 90.

 

Best of Luck!

[peeeot]

Crazy K, do I want to sell what?

 

Lee, I've gathered that the vacuum conversion is very in depth, and honestly it's more trouble than I want to go through for this car. I like it, but I'm not a w-body fanatic or anything. I've searched local yards (mostly by phone) for any ABS-equipped Cutlasses or siblings of the right vintage and nothing has come up. Either the yards don't have cars that old or the ones they have don't have ABS. One yard didn't know what they had and I drove out and looked myself. There were around 4 or 5 candidate cars, none had ABS. I didn't look under hoods; I looked right where the valve should have been. They all had 2 steel lines where the valve should have been.

 

Given that the cause of the leak is rotting rubber, I feel like finding a used, 15 year old valve is not worth the trouble, and plan on simply obtaining a new valve.

 

Now I have a new cause for fear. I pulled into the parking lot and the ABS pump wouldn't stop running, even with ignition off. I turn the ignition off, on, press the pedal, etc, nothing stops it except pulling the motor fuse. The prop. valve was not leaking. In the fluid reservoir, I could see the disturbance in the fluid caused by the pump operation, but the fluid level was not changing.

 

After reading information here http://www.tpsgarage.com/TGP/brakes/powermaster.htm and price checking parts from oehq.com, I'm very worried.

[Crazy K]

Crazy K, do I want to sell what?

 

the car, actually. I am crazy enough to do a vacuum brake conversion. done one already, to MY 91 vert.

[peeeot]

Crazy K, do I want to sell what?

 

the car, actually. I am crazy enough to do a vacuum brake conversion. done one already, to MY 91 vert.

 

Hey, make me an offer I can't refuse, and, well, I won't be able to refuse! I am debating whether I want to keep the car or not at this point. The last thing I want from a car that is supposed to be economical, reliable transportation is headaches about my brake system.

 

Incidentally, do you know whether it's okay to drive the car with the ABS pump motor not cutting off?

[Crazy K]

where are you located, and what did you pay for it? I really do not need another car! besides I am looking at another vert today, already!

 

I do not think it is safe to drive your car, but please rear thru the following for more info than you would ever want to know.

 

http://www.tpsgarage.com/TGP/brakes/powermaster.htm

[peeeot]

I'm in Raleigh, NC and I paid $1800. I have a post on it in the members' rides forum that includes links to pictures.

 

I have the site marked as a favorite. The information has been pretty key to me having a clue about this system. I just wish it had part numbers for all the parts it lists (esp the motor relay).

 

I won't drive the car until this is addressed. Too bad it's the only one I've got!!

[peeeot]

Good news! I got the pump to stop running!

 

I was trying to get a part number for the motor relay and had to remove the relay from under the hood. With the engine compartment cool, I had no trouble removing it. Ultimately, I found the current GM part number, and priced the part. When I put everything back together, the pump operated the way it had been before. So it would appear that my relay was sticking or otherwise not operating properly. I'm going to replace the proportioning valve and hopefully the system will behave properly from then on. If it starts acting up, I know where to check.

 

For every Powermaster III owner's benefit, I'll list current part numbers and the best prices I've seen for the parts.

 

1. ABS pressure switch. GM # 88927270 List $325.26 Buy at gmpartsdirect.com for $112.49

2. ABS accumulator GM # 88927271 List $370.74 Buy at gmpartsdirect.com for $131.59

3. ABS Rear proportioning GM # 88927272 List $204.24 Buy at gmpartsdirect.com for $65.21

valve

4. ABS pump motor relay GM # 88927273 List $291.50 Buy at gmpartsdirect.com for $96.70

 

Hope this helps someone.

[Crazy K]

glad you are getting it figured out.

 

and for the info of all I now own TWO W Body Convewrtables!!!!!

[peeeot]

Well, I ordered my new proportioning valve on the 10th, but it still hasn't shipped from gmpartsdirect.com. The site says the order status is "special ordered," which the site says could take more than 10 business days before being shipped.

 

In the mean time, the red brake warning light has started coming on sporadically. It used to flash on just when I first pushed the pedal sometimes, but lately it has started coming on and staying on, even when I'm not touching the brake pedal. My shop manual tells me this means accumulator pressure is below 1800 psi--not good. (I've checked for parking brake and fluid level)

 

Then today, about an hour ago, I was driving back from the gas station and I lost power assist more than once. It is still somewhat intermittent; I would push the pedal and have power assist temporarily and then I'd lose it, or I wouldn't have it at all, or I'd have it through braking. At this stage I don't know what I'm gonna get.

 

It takes a lot longer to stop without power assist, and only the front brakes are working, so I don't think I'm going to be driving my car any more until this is fixed. Since it doesn't seem like the already-leaking prop. valve can be responsible for this new development, I'm concerned that the accumulator or pump/motor or relay has bit the dust.

 

Oh well. I have the worst luck with cars.

[Crazy K]

try an accumulator?

 

you read through the tgp garage website? it should help diagnose

[peeeot]

The part (prop. valve) arrived today and I installed it. I haven't finished bleeding the brakes yet because I ran out of fluid. The fluid in the entire system was really filthy; now you can easily see the bottom of the rear reservoir but the bottom of the front reservoir is still hidden in a fog of dirty fluid. There is a light layer of sediment at the bottom of the rear reservoir that I don't know what to do about. Also, when I was bleeding I'd get little particles of who knows what (hopefully not rust!) in the fluid here and there.

 

By the time I finished with the one wheel that I bled, the fluid was much cleaner. I have hopes now that replacing this valve will actually solve my brake problems. Perhaps they are unfounded though.

 

I was surprised to see the big rubber plug on the new prop. valve. For one thing, I thought they would have improved the design; for another, the rubber is totally absent on my old valve!

 

I'l post an update when I finish with the repair.

[peeeot]

No dice. I've replaced the valve and bled the system as best I could per the shop manual's instructions. The only part that may not have been done adequately was the isolation valve bleed, because it was so hard to get a fluid catch can in there and make sure all bubbles were removed. I didn't see any bubbles though.

 

At the end of my efforts, these are the symptoms of operation: brake pedal is perfect when ignition is off. Hard as a rock after an inch or so of travel. Turn the ignition to "run", and press the pedal, and the pedal will sink down a few inches, accompanied by a running pump motor and a red brake warning light. At the bottom of travel, a slight bump occurs, the red light turns off, and the pump stops. If held at the floor for a few seconds, the pump will blip on and off every couple of seconds, accompanied by a flash of the red warning light. The first time the pump blips, the ABS light starts flashing and continues on until the ignition is turned off.

 

The new prop valve is not leaking, nor do I see evidence of leakage anywhere else.

 

I should also note that the pump runs for only 3-5 seconds after fully depressurizing the system, which doesn't take 40 pedal presses based on the feel of things. The manual says it should take closer to 30 seconds.

 

I'm thinking the accumulator is at fault. It sounds like most people will have had to replace their accumulator by this point, after more than a decade.

 

The driver side rear brake caliper doesn't release fully. It releases enough to turn the wheel, but the pads are definitely still touching the rotor. Could this be a part of the problem, or a symptom of it?

 

Should I just buy a new accumulator, or would I be better off taking this to a professional before buying more parts?

 

 

[Crazy K]

replace the accumulator. you would never find a professional to fix this anyhow!!!

a diagnosis and info guide.

http://tpsgarage.com/TGP/brakes/Braking_main.htm

http://tpsgarage.com/TGP/brakes/powermaster.htm

 

 

as for the rear brakes, the probelm you noticed has nothing to do with the PM3. if has to do with the crummy design of the 93 and down rear brakes (94 and down lumina as well)

 

I recommend upgrading to the rear brakes of the 94 and newer.... note that I have done so on mine using junkyard parts from recently serviced cars at a minimal cost.

here's how:

http://tpsgarage.com/TGP/brakes/rear_brake_upgrade.htm

[peeeot]

Thanks Crazy K. You agree with me, then, that the accumulator is the probable cause?

 

I read all those pages on the tpsgarage site. I can't believe that GM actually put such problem-prone parts and systems in their cars. It looks like the caliper swap is easy but the parking brake requires welding, which I can't do. I'll deal with those calipers in due time, I guess...

[peeeot]

I got my Prior remanufactured accumulator and installed it yesterday. The operation of the brakes was much, much better, and seemed to fit with the description of how it's supposed to operate in both the tpsgarage site and the factory shop manual.

 

BUT.

 

Now all of the brake warning lights (red and amber) are on all the time. I don't understand how that's possible. Did I not bleed the brakes thoroughly enough or something? According to the information I have about what triggers the red light, that shouldn't be the problem. I can't think of anything else though. And the ABS light used to turn off after the initial check and some back on when I pushed the pedal (because the pump would run). Now it turns off very briefly and comes back on right away, before I touch the pedal.

 

I really thought the accumulator would take care of all this. Any ideas?