03 suburban 4WD problem

[rdharley3]

I own a 03 1/2 ton sub with 170k the problem I have had for the last 6 months is with the 4WD system when started you never know what position the drivetrain is going to be in 2W hi, 4WL, 4WH, or 4WAuto. Most of the time I just put it back min to 2 wheel drive but there have been a few times when it would not shift from 4 wheel low to 2 wheel drive unless I turned the truck off and let it sit for a couple of hours.

I replaced the push button drive module on the dash and no change. Any help on what this problem could be will be greatly appreciated.


DGS

[gmtech1]

Originally Posted by rdharley3

I own a 03 1/2 ton sub with 170k the problem I have had for the last 6 months is with the 4WD system when started you never know what position the drivetrain is going to be in 2W hi, 4WL, 4WH, or 4WAuto. Most of the time I just put it back min to 2 wheel drive but there have been a few times when it would not shift from 4 wheel low to 2 wheel drive unless I turned the truck off and let it sit for a couple of hours.

I replaced the push button drive module on the dash and no change. Any help on what this problem could be will be greatly appreciated.


DGS

There will be a code stored in the TCCM, probably a C0327. You most likely have a bad encoder sensor. It's inside the encoder motor. Not too tough to replace.

[rdharley3]

gmtech1 thanks for the info I will check for the code and reply back with my findings.


DGS

[rdharley3]

The problem has been solved. Here is what I did to fix this.

I shoppped around and finally found a shop that would read the codes On the TCCM for a reasonable price one shop wanted $120 to read the module I finally paid 37.50 plus tax I explained to the mechanic that all I wanted to know is if 1. the encoder motor needed to be replaced. 2. the sensor in the encoder motor needed to be replaced. and 3. if the TCCM needed to be re-flashed. It was determined that the encoder motor needed to be replaced.

Others that have replacced the encoder motor dropped the front drive shaft to get the middle bolt out I did not there is enough clearance to get the bolt out and remove the old motor I did need to move the front drive shaft around to get the last few turns on the bolt but it worked also these bolts have loc-tite on them and the top bolt and middle bolt were a fraction of a turn at a time getting the bolts out and back in took the most time, but now all weorks just fine....gmtech 1 thanks for putting me on the right path you saved me from 300-500 in cold hard cash...

RDH

[gmtech1]

Originally Posted by rdharley3

The problem has been solved. Here is what I did to fix this.

I shoppped around and finally found a shop that would read the codes On the TCCM for a reasonable price one shop wanted $120 to read the module I finally paid 37.50 plus tax I explained to the mechanic that all I wanted to know is if 1. the encoder motor needed to be replaced. 2. the sensor in the encoder motor needed to be replaced. and 3. if the TCCM needed to be re-flashed. It was determined that the encoder motor needed to be replaced.

Others that have replacced the encoder motor dropped the front drive shaft to get the middle bolt out I did not there is enough clearance to get the bolt out and remove the old motor I did need to move the front drive shaft around to get the last few turns on the bolt but it worked also these bolts have loc-tite on them and the top bolt and middle bolt were a fraction of a turn at a time getting the bolts out and back in took the most time, but now all weorks just fine....gmtech 1 thanks for putting me on the right path you saved me from 300-500 in cold hard cash...

RDH

Glad to see you got it fixed! Thanks for the update!