Unwanted ABS 2004 GXP
 

I will be driving my car straight on dry pavement and when I hit the brakes the ABS system turns on and I can not stop. This happens about once a month. The Dealer can not reproduce it and there are no ABS faults. The message center says "Service Stability System", the code there was for the stearing sensor. The dealer said this would not cause my issue. Also, sometimes when driving the "Low Trac" light turns on for a few seconds (again on dry pavement). When I hit the brakes during this fault the brakes act normal so I am not sure if they are related. I feel my car is unsafe to drive since this problem caused me to run a red light last week. The dealer says they can not fix because they can not reproduce the issue and send me on my way after charging $70 to read the codes. This is my second dealer...... Please help.

the stability system notification is for the position sensor simple fix https://www.gmforum.com/mechanical-134/replacing-steering-wheel-position-sensor-2000-a-287531/ i have a spare sensor hanging around to fix that. but the rest sounds like a bad wheel speed sensor (hub) but that will usually have a code to go with it unless it's intermittent

I would check the plugs on the wheel speed sensors, if they are dirty or corroded they will randomly send a bad signal and cause issues with the braking and stability system.

If you lose all brakes when these lights come on you must have either a brake booster problem or a hard\mechanical failure some where because the stability system and ABS in my 2000 Bonneville has not worked for about 6 months now and our brakes are as firm as when it worked.

I would check your wheel speed sensors. Make sure they are in tight. Better yet, unplug each one and squeeze a little dielectric grease or Vaseline into each female connection and replug tightly. If one is intermittently breaking contact a fault code wont register. Ever get an erratic low tire pressure on you DIC?

Yes I do get the tire pressure alert at times. not as much as the breaking problem though. Are the sensor connectors easy to get to ?

Yes, turn each wheel in all the way and their easy to spot. Only two wires going into the back of the wheel assembly. This is off a 2002. But very similar.

https://www.gmforum.com/attachment.p...1&d=1269521518

while you have sensors disconnected measure resistance accross sensor terminals wiggle a little see if any changes. correct resistance is 850-1350 ohms. Also spin wheel and measure AC voltage accross sensor terminals. correct voltage is 100 mV if you are checking you may as well make sure problem is not there.