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This is in reference to an 03 Rendezvous w/ a completely rebuilt engine. Mechanic has cannot locate problem as it does not happen when he test drives vehicle. Best I can equate problem to is when I brake normally the foot pedal “stutters” or “hiccups” and the ABS Light, Service light and one other come on. The car drives well and other than having to replace window motors 3 times there is no other issue. Can you suggest a repair.

The problem is more than likely in your ABS system. It will have to be checked by a good, independent mechanic. Cleaning of the ABS sensors may help but it still needs to be checked out.

AHA! I have had the same problem. Replaced the brakes and a week later it started again. It happens most often when I first start the car or at slow speeds. The “traction active” light comes on and it stutters like the ABS is trying to engage.

The local mechanic spent an entire day and couldn’t figure it out. The error codes change from ABS to traction etc. So I did some research and think I found the problem.

The Pontiac Aztek is basically the same car and there is a crazy group of folks out there who work on them non-stop! From what I can tell, it seems that the problem is because of the wiring harness and the connectors. The real problem seems to be where all the wires come together under the left passenger seat. It seems that if water gets into the car, the wiring is not protected and then things go down hill.

This if from a GM expert:
OK, more than likely, there is a broken wire going to one of the front wheel speed sensors. The “acting strange” was actually the ABS engaging. Because these wires flex everytime you turn the wheel or go over a bump, after awhile the wires inside the insulation begin to break (although the insulation remains intact, making it appear visibly sound). These breaks in the wires cause intermittant connections, which the ABS controller reads as “wheel lock-up” and engages the ABS. After some time of doing this, the breaks in the wires start to pull away, which causes the ABS controller to set a wheel speed sensor fault code, turn the light on, and disable the ABS.

Two things to keep in mind:

  1. there are only two ways to know which wheel is causing the problem, and thats either use a scantool and have the ABS fault codes read, or remove the insulation from the speed sensor wiring harnesses and find the break (usually within 8 inches of the sensor connector).

  2. Most shops, when they see a wheel speed fault code, automatically assume the wheel bearing (hub) is bad, since the sensor is internal to the hub. I would estimate that 3 out of 5 speed sensor codes are NOT the hub, but the wiring to the sensor, like I mentioned in the first paragraph. GM sells replacement connectors with wiring to repair this, if that is indeed the case.

Read more: Anti-lock warning light on, 2003 pontiac aztek - JustAnswer

@brsmith Huh, good answer. Ask and ye shall receive I guess.