The family cruizer (2002 Buick Rendezvous) is acting up. The ABS system pulsates and the ABS pump motor runs from time to time. Sometimes when easing to a stop it feels as if you're going to run out of peddal. It's got my wife scared half to death.

I've been looking through my 2002 Camaro service manuals - visually it looks like the ABS system is very similar. Unfortunately it seems that an ABS scan tool is required to follow the diagnostic trees. I was hoping that someone may have some experience to share.

We paid GM about $95 to tell us they couldn't find anything wrong with it. I haven't done much myself so far. I removed the ABS control module connector, scuffed the terminals and reconnected it. Unfortunately it acted up immediately afterward, so I'm less inclinded to think it's a bad connection at the connector.

I wondered if there could air in the system (not sure how that could happen). My Camaro manual talks about an automated bleeding procedure that cylces the valves in the AB module. I can at least try a standard bleed to see if that helps.

Does anyone have experience with the ABS pulsating and buzzing when you try to stop?

Could the valve be at one axle verses in the middle?
Wheel speed sensor might be bad or loose connection, one for each front wheel and/or one for driveshaft or each rear wheel.

Seems like I'd be returning to dealer with receipt if in 30 days? Good luck overall.

if abs light isnt on a mechanic cant get code. but he can check while you braking and see if all sensors are at same speed. if 1 is off little bit by others. it picks up slipping and applying anti lock. but not enough to throw a check engine light on. if you went to gm bring it back and have mechanic go for ride while you drive as he monitors comp. tire pressure low in 1 tire will also cause it. make sure all tires are same pressure and same size. also all 4 are same brand name. dont think that 1 tire is a different brand but same size. each brand has its size and actually they arent. hope it helps you out.

Good tips, thanks for the suggestions. That helps me visualize the types of things that could be causing an oscilation. The ABS light is not on. I don't think it comes on when it acts up either, but I'm not certain of that. I put 4 new tires on it not too long ago. They should all be the same diameter etc. but it's worth a closer look. I've had tires separate on me before so it's possible one is not the same as the others if one is failing. I'll check the tire pressure. They should be close since I just topped them off less than 2 weeks ago. Unfortunately this problem has came and went in more than 30 days, so I'm not sure I have a warranty coming to me, but I had better check my receipt to be sure.

With your situation, just like was mentioned above is most likely a wheel speed sensor dropping out. I have seen this a lot and it is funny how they tend to drop at lower speeds which causes the pump to engage and cause the feeling you described in the petal. Even if it has been over 30 days still take it back to the dealer and talk with the service manager and explain it has continued to happen and you just need a tech to ride with you and let him monitor the speeds with the tech2. If the shop has a shop forman request him, as the guy who looked yours over may be a flunky and not know more than where the engine and rearend are, those types are everywhere even the dealerships. If you want to drive to NC, haha, I will be glad to check it at my dealership

With your situation, just like was mentioned above is most likely a wheel speed sensor dropping out. I have seen this a lot and it is funny how they tend to drop at lower speeds which causes the pump to engage and cause the feeling you described in the petal. Even if it has been over 30 days still take it back to the dealer and talk with the service manager and explain it has continued to happen and you just need a tech to ride with you and let him monitor the speeds with the tech2. If the shop has a shop forman request him, as the guy who looked yours over may be a flunky and not know more than where the engine and rearend are, those types are everywhere even the dealerships. If you want to drive to NC, haha, I will be glad to check it at my dealership

Thanks tumper. I know what you mean. I think the first step of their procedure was to scan for codes and then take it for a test drive expecting it to act up and sound the alarm. I doubt very much that any detective work was expended beyond looking for the code and a big idiot light saying "HERE IS THE PROBLEM...REPLACE THIS!" :D