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Speed sensor circuit

DOMDOTCOM

New Member
Joined
Jun 9, 2018
Messages
4
Hello forum, I bought my 2009 Z71 LT Avalanche last June and haven't had any problems since.  Recently I have been getting codes "Service Stabilitrac..Service Traction control..Stabilitrac off...Traction control off.." and ABS light on.  It was doing it intermittently and would sometimes come on during start up, sometimes when driving.  It would always go away for a couple days then come back randomly.  It stays on now so I took it for a code readout at and auto place.  Code read was "REAR LEFT SPEED SENSOR CIRCUIT", now, Iv'e heard of people with the same dash lights on with loss of power also.  They said they called *ONSTAR* and that was the problem?  This is not happening in my truck, I do not have "LOSS OF POWER". I called ONSTAR they told me they could do nothing.  The only 4 wheeling I've done is driving on sand at the beach maybe 5 times last summer.  I actually just drove it on the beach last week with the dash warning lights on and there was no problem. 
Has anyone else had this problem?  I'm just wondering if it really is the SPEED SENSOR or some other underlying problem.  Just asking before I buy a new sensor circuit and install it.

Thanks for the help!  BTW, only 81k miles.
 
Also, it is ALL stock except for rear door speakers.  Just aftermarket same size speakers in rear doors.  No lift or different wheels/tires, nothing has been done to it yet.
 
Pull your wheel off and inspect the area around your brakes. Insure the ABS sensor is not damaged.

See picture if you are not aware of where this is...

If that is not it then its the tone ring. I have attached a PDF that shows replacing the tone ring. In other vehicles the tone ring would be built into the wheel hub. Not sure how that works on the trucks. I believe in the 1st gen the speed sensor is integrated into the rear end but 2nd gen they moved them to the wheels. May be on the wheels in 1st gen if they have traction control as well. Not sure.

I only spent like 2 minutes to pull this up in my service manual so I did not look any further into it but this can give you an idea what your looking at. I know earlier models were prone to getting rust stuck on the tone ring which would make intermittent issues like you are complaining about. Since it is a magnetic ring it can grab onto rust particles. If that is the case you can remove them but you may want to do a google search for people that have done it. Maybe others here have better ideas.

I believe this is an issue on first gens but only with the front wheel sensors. But I believe in those the tone ring is built into the wheel hubs.



 

Attachments

  • replace tone ring.pdf
    396.8 KB · Views: 3
  • 09 speed sensor.PNG
    09 speed sensor.PNG
    11.3 KB · Views: 14
OK thanks, I'll check into it and post results.  I'm hoping it is just dirty or rusty and can be cleaned.  Unfortunately, I'm at work so I will have to sneak off to get a look.  I'll look at some youtube videos as well and let you know.

Thanks for the quick response,

Dominic
 
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