I started my truck and started to drive away to get some coffee when I noticed the speedometer needle start to bounce around. Just seconds later the abs light, brake light, and message center reading (service brake system) came on. Then the transmission started searching for shifts. This is a random thing thatseems to happen more with a warm transmission than not, but has happend with a cold transmission. It will happen at any speed also, but usually at speeds over 30 mph.I figured it was a badspeed sensor wire since it is random and the sensor seems to work most of the time, but I took it to chevy anyway to comfirm.
They diagnosed it and came back with bad rear wheel speed sensor. I picked up the truck and and grabbed the $50 sensor and went home.
While under the truck I noticed that the sensor connector was bad and the clip that holds the connector to the sensor is bad. So I returned the sensor and purchased a ac delco weatherpac connector from a local parts store. It came with two wite wires instead of the colored wires so I made sure it was connected correctly with the same amount of pig tail I removed when I cut the old one off. Sure I had fixed the problem My wife and I took off and it happend again.
By this time I was starting to hate my decision to buy this truck.
Is it possible that the sensor is bad? It is my understanding that when a sensor goes bad, it just goes bad. It is not a random thing like I am dealing with.
Anyone have a clue. This has been the first thing I have ever had stump me like this.

Bill

 

This is the spped sensor on the transfer case?...any idea what the code was?

 

Yes it is the one on the transfer case. I don't know what code they got, but my own scanner pulled no codes. They just told me the sensor was bad, and that their scanner could go much deeper than mine.

Bill

 

Yeah,,,cheaper code readers only read the ecm...it takes a 4k tech2 to read the brake module..radio..cluster,etc


If its turning on the amber ABS lite,you have abs codes...perhaps its a front wheel sensor...or the ebcm itself..(Hope not)..

 

Well after a trip to chevy parts counter this morning, the problem is over. It was infact the rear speed sensor. It took me one minute to change and get back out on the road to test. I did make an appointment to have the programming changed for 285/75 tires.
Is this all that the dealerships can change or is there mor things they can alter, like deleting torque managment. Or are they limited gm or tools to do so, or is it a dealer by dealer thing?
I hate torque managment as it gives no power till the truck hits second gear, thus a wast of fuel and energy.

Bill

 

no..dealers can change tire sizes (gm charges us for that,btw)...and can do gm updates..but can't really "change" anything like your talking about.

mostly the updates are to correct a false code setting,or something like that.