ABS kicking when stopping & Stabilitrak light coming on from dead stop

shooter43

Original poster
Member
Aug 3, 2015
2
I'm an old guy with most of my experience on cars pre 1975 so the new ones are a challenge. I have a 2007 4.2 inline Trailblazer with abt. 72k miles. Symptoms are, usually under 5mph when stopping the ABS kicks in, seems to be one problem. After consulting the forums, I have removed, cleaned all surfaces & re-installed all 4 ABS wheel sensors.

Second condition is, when starting from a dead stop the stabilitrak light comes on & the engine sounds like it may stall. This only lasts for 1 -2 seconds then light goes out & engine runs normal. Now this problem seems to happen most frequently on the first trip of the day (but on occasions at other times). Back out of my driveway, put it in D start to pull away & that's when in occurs. If I disable the Stabilitrak as soon as I start the car I don't have a problem with the Stabilitrak. (for the sake of full disclosure). Went to Autozone & their code reader found no codes.

Note: I disconnected the front drivers side ABS sensor & both problems went away. (Made a 200 mile trip with it disconnected & no problems). Replaced that ABS sensor, reconnected it & both problems returned.

Question: If I disconnect one (any) wheel ABS sensor does it disable the entire ABS system & the Stabilitrak system or just the signal from that one wheel? An answer to this question & that will help in my trouble shooting.

Passenger side wheel hub/assy replaced at abt. 63k miles.

Am considering, 1. Buying one rear wheel ABS sensor & swap out one rear wheel ABS sensor, if that doesn't fix the problem on one wheel then swap with other wheel sensor. If that doesn't fix it then. 2. buy second rear wheel ABS sensor. If that doesn't fix it then, 3. replace driver side front wheel hub/assy. As of now I have no obvious bad wheel bearing signs but I have read that there can be a delay between symptoms I have & bad wheel bearing symptoms.

Before proceeding any further will greatly appreciate any advice/suggestions.
 

Tiggerr

Member
Jun 6, 2013
1,324
Perrysburg, OH
If it was me I'd replace the drivers side hub. Sounds like there's where the problem is. Pretty sure the stabilitrak uses the data from the abs sensor. The reluctor in the hub could be bad. I aways do both hubs when I do one. I see you did the pass side earlier, so I wouldn't replace it
again.
 
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HARDTRAILZ

Moderator
Nov 18, 2011
49,665
Is there any play in the hubs?
 

Sparky

Member
Dec 4, 2011
12,927
When I was having odd ABS triggers it ended up being the hub. Hub started making a racket a few thousand miles later.
 

neohio

Member
Nov 11, 2013
85
I am having a similar issue right now on my 08. All codes lead towards SWPS(2nd condition) and brake light switch(1st conditionn).
Mine turns on the ABS pump at lows speed as well, right around 5mph.

My truck also turns on stability control first thing in the morning. So lately I have gotten in the habit of disabling it before even moving it in the morning.
C0455(SWPS), C0161(brake pedal position) are the only codes in my truck right now.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
The StabTrak in morning is likely the steering wheel position sensor.

I had all the same slow speed stuff with a bad hub and a new one that was bad from the get-go. The new one had me searching everywhere til i swapped in a spare "just to see" if it fixed it. Got the vendor to send me another new one and all was good in the hood.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
neohio said:
I am having a similar issue right now on my 08. All codes lead towards SWPS(2nd condition) and brake light switch(1st conditionn).
Mine turns on the ABS pump at lows speed as well, right around 5mph.

My truck also turns on stability control first thing in the morning. So lately I have gotten in the habit of disabling it before even moving it in the morning.
C0455(SWPS), C0161(brake pedal position) are the only codes in my truck right now.
The ABS issue doesn't usually give codes but 90% of the time points to a defective wheel hub. There are usually no other signs except if you let it go, the hub will start making the usual failure humming noise, like Sparky said. If both are original, you could consider replacing both.

For your Stabilitrak issues, start by replacing the SWPS, which has a high failure rate. Then if still getting the error for the brake pedal, replace that sensor/switch.

Fix one thing at a time as sometimes one problem may trigger another that isn't really at fault.
 

24v 4.2

Member
Jan 16, 2013
430
I would lean toward the hub as well or the wiring for it.

I had a similar Stabilitrak issue, and it was fixed by replacing the hub. I had no hub noise btw.
 
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shooter43

Original poster
Member
Aug 3, 2015
2
Thanks for all the replies. It sounds like hub replacement is the way to go first, & will place an order today. I would like to know if anyone can give me an answer to this question tho;

If I unplug one ABS wheel sensor, are both the ABS & Stabilitrak systems completely disabled or just the signal from that wheel.

Thanks to all again.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
It will disable them. ABS of course because it won't know its speed and the Stabilitrak it needs input from all the wheels and the steering wheel to know how to apply the brakes and pull back the throttle during a skid.
 

freddyboy61

Member
Dec 4, 2011
276
Can I suggest a step before replacing hubs. I found that cleaning the surface under the wheel sensor would stop the slow speed ABS application. The cleaning needs to be very thorough, using a Dremel tool to get down to a clean rust free surface.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
It is a good suggestion worth attempting but I have yet to see anybody fix this problem with a cleaning of the sensor. Most have been defects/failures of the hub assembly
 

freddyboy61

Member
Dec 4, 2011
276
Moose - it worked for me. I had even replaced both sensors, without cleaning the mounting surface, and still had the slow speed ABS engagement. Cleaned the area thoroughly and all is well. I'm not saying this a fix all, but might be worth a try before changing expensive parts.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Well then, you're the first :thumbsup: . Like I said, it's worth a try and costs nothing.
 

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