[MightyPirate]

Okay, so I have a problem with a 1999 Pontiac Grand Am but I can't seem to find an active Pontiac Forum (wtf guys, answer my posts). So, any help would be appreciated:

"My girlfriends 99 Grand Am decided that it was going to have braking issues a few nights back.

Symptoms:
-Very mushy brake pedal, still brakes okay but there is definitely some air in the system somewhere. Seems to brake fine but you really have to push on the pedal a lot more than usual. Happened more or less all of a sudden. Isn't getting noticeably worse though.
-ABS, Trac Off, and, briefly, the battery light all came on. After stopping and starting the car they would go off but come back within a minute or so.
-Had full brake fluid 4 weeks ago, checked it yesterday and it gone 1/4 of the way from MAX to MIN, not a huge amount but obviously a leak somewhere.
-Checked all the lines, both front calipers, the brake pedal, and all around the master cylinder. No leaks that I can see. Put it in the garage and topped it off. After playing around with it for about 2 hours it had gone down a very tiny bit but still not a drop anywhere I could see.
-Bled the front two lines and topped it off, no change but the lights went away for about a 50 mile drive and then came back. Can't bleed the back cause I cant get a 8mm socket on the nut there (strut bolt in the way) and I don't have a 8mm wrench. Getting one tomorrow and then I'll check the rear drums for leaks.

So, obviously I have a leak somewhere. My thoughts are the master cylinder or the ABS regulator. I couldn't find the ABS unit though, anyone know where is it on the 99 grand am? Also, is there a special process for bleeding the 99 grand am cause I read online that some have to be bled at the ABS unit as well? It's still drivable but who knows for how long."

So, I'm thinking I should start by replacing the master cylinder after I check the rear drums but I'm REALLY tight on money (girlfriend got laid off, helping her out) and I can't afford to just throw parts at the car.

 

[B3NN3TT]

Man; ABS is great until you have to service it.

I always assumed the ABS unit was connected to the master cylinder.

A faulty master cylinder would generally have different symptoms. When I experienced MC failure (not in the Cougar), the pedal felt fine at first, then leaked down as you held it in, so the pedal just inched closer and closer to the floor instead of holding pressure.

 

[MightyPirate]

I always assumed the ABS unit was connected to the master cylinder.

Me too but from what I read it seems that 'most' GM vehicles have a separate ABS unit with it's own bleeder valves. However, since I can't seem to find it and after finding a brief post the other day about the 99 grand am not needing any special bleeding (the validity of the poster is definitely in question though) I think I must just be overlooking it and in any event I should probably leave that for last.

A faulty master cylinder would generally have different symptoms. When I experienced MC failure (not in the Cougar), the pedal felt fine at first, then leaked down as you held it in, so the pedal just inched closer and closer to the floor instead of holding pressure.

Well, that's sort of what's happened. The pedal has definitely got some more play in it before actual braking occurs than it did before but it also does do exactly what you described where I can push on it and push on it and it will brake but it will also go all the way to the floor. Though, after re-reading what you said, do you mean that it would go to the floor and not come back up? Perhaps I just have a small leak internally in the MC so that it's losing pressure and introducing air into the system?

Oh, and if you're wondering about the TC light being on that's apparently cause the traction system and ABS systems are so linked in the grand am that they both come on if somethings wrong with one or the other.

Anyway, found a good deal on a master cylinder so I think that might be the place to start. Can anyone recommend a good bench bleeding kit or is the $8 NAPA special the way to go?

 

[MightyPirate]

Update:

So, talked to my girl-friend a bit ago and she said that after a quick drive it seemed to be loosing power and shuddering. WTF is that all about?

Anyway, does anyone have any idea where the ABS unit would be and any advice on how I should proceed?

P.S. If you search google for "1999 pontiac grand am abs regulator" this post comes up 4th, sometimes google's speed amazes me.

 

[eric]

in case anyone's still out there looking for this.. on a 99 grand am.. the lines that run from the master cylinder to the ABS go under the air intake/filter and under the battery.. the air intake comes off with a couple of bolts.. the battery is a little more of a pain in the neck because you have to remove the tray and of course it's probably rusted.. i had to drill out the three bolts that hold the tray.
after all that you have about an inch or so to work in.. good luck.

 

[RiverRojo]

The MC may be leaking inside of the brake booster. That may be why you're not seeing a leak. As for the abs/tc lights, you most likely have a bad wheel speed sensor on the front axle. Hopefully a wire just got damaged and you can fix that yourself.

 

[MightyPirate]

The MC may be leaking inside of the brake booster. That may be why you're not seeing a leak. As for the abs/tc lights, you most likely have a bad wheel speed sensor on the front axle. Hopefully a wire just got damaged and you can fix that yourself.

Well, I guess since we're digging this up. The final issue ended up being a bad wheel sensor but I couldn't get to it without taking off the hub (at least that I saw). Never did find the leak though but it's like 1/10 of the fluid over the course of 6 months so whatever it is it's REALLLY slow (either that or some of the fluid is evaporating or something, not really sure if brake fluid can do that). Another weird thing is Pontiac (or prior owner, not sure who) used aluminum bleeder valves on the steel brake calipers so, a bit of galvanic action later, the damn valves rusted themselves to the calipers and we had to replace the whole caliper to bleed the system, what a waste of money.