4x4 problem

Big truck 32 · January 31, 2020

Hi I got a 94 Chevy heavy 2500 5.7L I can't get my 4x4 to engage it's a floor shift transfer case. I put it in for and it locks the drive shaft to the front diff in and the actuator was just replaced and I get nothing I tried backing up and going forward and it does nothing.

davester · January 31, 2020

Test if the actuator is getting power/ground at it's electrical connector. Or just unscrew the actuator from the diff and see if it goes in/out as the truck is shifted between 2wd and 4wd.

It could be anything from something busted inside the transfer case (TC), to the mode sensor in the TC, to a wiring problem between the TC and the actuator up front, to the fuse being blown, to something busted inside the front diff.

Big truck 32 · February 1, 2020

It gets 12 volts and moves in and out when shifted. And the fuse isn't blown. It work yesterday then I went for a drive and got stuck and I couldn't get it in 4x4

davester · February 1, 2020

Well, if the actuator moves in&out correctly, then shift into 4wd (with the actuator screwed back into the diff), and lift up one of the front wheels.

If you can still rotate it, then something is busted in the front diff, most likely the passenger side stub axle or the ring that locks the front diff together (this is the piece that the actuator moves), but potentially could be other bits in the diff.

If you can't rotate it, then the you are in 4wd. If you feel this doesn't happen all the time when you shift into 4wd, you a) have to test if you are in 4wd or not doing something similar (lifting one of the front wheels and trying to rotate it, and b) you might have some kind of intermittent problem, which will suck to figure out.

Big truck 32 · February 2, 2020

I lifted the whole front end and put it in 4x4 and spined the driver's tire and the passenger side I can hear a clunk as it turns

davester · February 2, 2020

If, (in 4x4 mode, with one front wheel lifted up), if you can spin the front driveshaft, then, most likely, the chain in the transfer case is broken.

If you can't spin the front driveshaft, then, most likely, the passenger side stub axle (in the diff, not the cv axle) is broken, or the locking ring in the diff is broken. It's possible other bits in the diff are broken, but those are the most likely to. It's possible to repair both of those by just unbolted the passenger side of the diff (it splits near the diff) so you don't have to remove the diff (you may loose some oil doing this, so have a bucket ready).