Hi I have a 01 lb7. All stock. TCase is stuck in 4Lo. Can hear the encoder trying to get outta the lo range, but cant. Dash flashes the selection but reverts back to the 4 lo. Ive read it may be the tccm, not the encoder. Both parts are pricey in Canada. I have an option of a reman case that comes with the encoder, but itd be real bad if after that it still didnt work. Any suggestions here? Truck has 270 kms, and Im sure will eventually need a case due to the dreaded "pump rub". Im not opposed to that but if the tccm is the problem I ll just replace that for now, and keep rolling miles on. Any help appreciated.
Encoder or TCCM?
- Thread starter nwodiesel
- Start date
I know I've had a few times where if it was in park there was a bind on the driveline from it rolling a bit after putting it in park and locking in the park pawl and it would not come out of 4lo. I had to put it in Neutral with brake off to release the load on the driveline and it came out. Just a thought.
I tried multiple times various ways...rocking it back and forth in park no luck. Just had a snapon scanner on it and the machine read that it was in high range, and that low range was inactive( reading from the tccm??) there is the problem, because its definitely stuck in 4 lo, and the dash selector is verifying that, yet the scanner is getting different information. Its as if the encoder either is out of time, or its getting a false reading from someplace.
I can get a new reman from gm with an encoder for a decent price, but Id like to verify it isn't the tccm first
Could pull the shift motor/encoder off and see if you can manually move it out of 4LO. May have a broken fork. Just don't turn the key on and hit a button.
Yes thats tomorrows plan. Like i said the scanner said the truck was presenting itself as in high range, but it clearly isnt. I figure if i can move it by hand then its probrably the encoder itself, if not then something is broken. Thanks
I have dealt with this problem on numerous trucks...... every one has been the encoder motor ring. You can waste money on a whole new motor or you can take apart the motor yourself and replace the ring with an AC Delco part for around $30 I believe.
So this is probrably an isolated issue, but seems the encoder case itself got so corroded between the encoder and transfer case, that when it tried to do its thing the case just lost its integrity, and buckled instead of turning the shaft, If I get a used one can I just touch power to the motor to turn and align it to the case, as I don't know what gear it was in upon removal. Anyone following me here?
It is not recommended to do that as it can cause damage to the encoder if it goes too far 1 way or the other. It is better to move the shaft to get it close and then put the motor up to it and move it around to get the shaft to line up. Once it is lined up in the motor turn the assembly, motor/shaft, until you can get the bolts in. Hope that makes sense.