2001 gm 4wd issues

[Stuck]

My buddy called today. Hes having issues with his truck 2001 2500 8.1 push button 4wd 4hi, 4lo with auto4x4. He lives 9 hours from me right now so I cant go look. Its also colder than hell up there.

He said when you hit the 4hi or 4lo button you can hear the transfer case shift but the front wont engage. 4Lo goes into lo but again the front wont engage. The lights just blink. He pulled the actuator and connected the new one but didnt install it. Left it on a milk crate so hecould see it. It didnt push out. My next thought was the encoder motor. If its the encoder it wouldnt shift into lo would it? I havent dug too much into the gm push button 4wd system so Im sure there is something Im missing. I dont know if the front shaft is spinning. He has it on ramps right now hes gonna put it on stands tomorrow. What else might cause the issue.

 

[cervelorod]

Had the same issue with my F-250 Friday. Couldn’t be bothered to get off the couch yesterday or today and clean out the shop enough to get it inside to take a look. Supposed to be in the 20’s in a couple of days and then I’ll tear into mine.

Read several things about the encoders getting out of whack and manually extracting the shaft to make it relearn can get it working. Need a shifter on the floor…

 

[total newb]

Pull codes.

Iirc 1382 is the encoder moder code.

The encoder itself is a small black dial, inside is a rotating maze of ciruit paths and 4 micro thin contacts that drag the over the maze and makes contacts at the right times. Basicaly a 1" record/lp with 4 heads.

the encoder activates the plunger. You can stick a screwdriver into plunger hole and push on the fork and roll the drive shaft and it should lock in.

It should be a splined encoder shaft. The motors are typicaly fine and its just the encoder dial itself, which is avaiable seperately and used to be about $65. Only takes 2 small torx bits to install into the motor. The motor is 3, 15mm bolts. Its easier if you pull the driveshaft but not manditory.

 

[total newb]

 

[total newb]

 

[Gdogg]

Pull codes, see if the front driveshaft is locked in to the transfer case. I had one GM and the clip that holds the right front axle shaft into the spider broke, so the axle shaft was disengaged. I had to put the truck on a lift and see what wasn't locked in to find it.

 

[total newb]

/\/\ one thing that happens is if the p-side axle pulls out far enough the thrust washer falls down and will prevent the slide collar from connecting the 2 inner shafts. This will be obvious when you push on the fork as i said earlier.

 

[Stuck]

First a big thank you to everyone for the help and advice. My buddy is finally whole again and able to plow.

So Einstein (it will be apparent shortly) calls me a couple hours ago. Tells he had ordered a new shift motor, and the sensor ring. He was going to try fixing the old one first.

He said he pulled the shift motor off the transfer case and there was a build up corrosion betwenn the shift motor body and the gasket and the shift motor case was all corroded. So he said fuck it and threw the new shift motor on.

Still not working, but it shifts the tcase faster. He cleaned up all the connections, di-greased the plugs, checked the wires. Still nothing.

He said he went back up front and pulled the actuator, bench tested it, and it was good. Checked the wires, yada yada yada, still nothing.

Thats when he called me. Were BSing, actually I was just listening to him rant about burning the thing to the ground, when he mentioned the airbag light coming on randomly.

So I asked him "didnt you just replace all the calipers, rotors and hoses last month?" He just got real quiet and said "I gotta go."

Apparently Einstein had unplugged a flat 4 plug near the rubber/steel brake line connection (maybe wheel speed sensor) when he did his brake job and forgot to plug it back in.

I shouldnt laugh too hard, god knows Ive done dumber shit, but holy fuck thats funny.

So remember boys and girls double check and make sure everything you fondle gets plugged back in.