My 05 z71 started getting the 4wd service message, and the dash lights would not be there, or would say 4hi, neutral, ect... when I was still in 2wd. Then it started putting me in safe mode and starting the truck in 3rd gear, so I had to get out and reset the battery all the time. so I started replacing parts cheapest to most expensive with the dash switch, front diff actuator, transfer case encoder motor, and still it wont engage. I can hear the encoder motor engaging, and it lets me put the transfer case in neutral, but 4hi or lo do not work? I'm running out of patience so if anyone has any ideas I'm all ears. thanks

 

What are the DTC's?

 

well it was stupid on my part and I never went to autozone to check them, I just started replacing parts... There was no ses light, only service 4wd message. and actually nothing since i installed the encoder motor. I even put the stock actuator back in, and nothing.. also checked all fuses that i know off.

 

There's a bulletin or two regarding intermittent 4x4 problems. Check the speed sensor harnesses and connectors for damage, and for continuity. Depending on which DTC is there, there are several other things that it could be. If the service 4x4 message illuminates, there will be a code set. If the light goes out, it will stay there as a history code. But I'm not sure if the AZ scanner will read the TCCM.

Did your new encoder motor come with a new sensor?

 

yes it was a new motor and sensor. if the encoder unit was bad, would it be able to switch in and out of neutral? come to think of it, i don't think i ever engaged 4wd after the new gears were put in, is there any potential for something to do with the gears to be the problem?

 

I'm not totally sure about that. I believe the sensor tells the TCCM when the t-case is in 4x4, and in low range. Not sure how or if it works with neutral and auto-trac.

I don't think so, you did have the front & rear gears swapped at the same time, and tuned the PCM, right?

 

yea front and rear were professionally installed and I tuned it the next day...

Does the tccm need to be re flashed or anything after installing a new encoder?

 

Not necessarily, but I'd bet GM has a reflash available.

 

There is an updated program that eliminates a lot of problems. But a code would really help.

 

I'll pay you good money to help me figure it out.