1997 GMC 1500 4WD won't engage and just blinks

[buddyp]

Took truck to a shop and put it on lift.Much noise from tcase when shifting and no power to front wheels so it looks I may have to gut it.

 

[Axewhlder]

I replaced the actuator today and still no luck. It's doing the same thing it was doing before. Buttons flash, I hear "engaging" noises and nothing. Then the new actuator was hooked up and not screwed in it didn't do anything either. Suggestions? I'm about to put a match to this damn truck.

 

[Axewhlder]

Also, when it isn't engaged the drive shaft will spin freely by hand. If I engage it then the D/S locks so the t-case should be good. I pulled the dash and the 4wd buttons and the connections seemed good. Are there vacuum lines or anything that can be affecting this?

 

[Vortec Lover]

I love my pushbutton- but I've never had problems with it either....

well, depending on how much time/money you have, this would be a good time to convert to manual 4wd lever and lower gears front and back.

 

[Axewhlder]

Eh, just interested in fixing the problem at hand. I want to get this truck running 100% before I consider putting any cash into it that I don't need to. haha

 

[dirtridinz71]

If in 4wd and the front driveshaft spins while moving then the tcase is engaged and working properly. Sounds like a broken wire or bad tcase switch, since no power going to the actuator, time to dig out the 12V test light

 

[Axewhlder]

Great..electrical stuff.. my favorite. Any suggestion on where I should start? Any brittle points on the T-case as far as harnesses?

 

[Vortec Lover]

Great..electrical stuff.. my favorite. Any suggestion on where I should start? Any brittle points on the T-case as far as harnesses?

Just start poking around till you find a dead one

 

[buddyp]

If in 4wd and the front driveshaft spins while moving then the tcase is engaged and working properly. Sounds like a broken wire or bad tcase switch, since no power going to the actuator, time to dig out the 12V test light

I have been chasing the same problem with my 97 z.One Transmission shop guy said he thought the tcase needed overhaul.They had it on a lift with and were not able to get the front wheels to turn.I took it home,marked, the frt drv shft with tape and with the 4wd shift in 4wd I drove back/fourth and the frt shft had turned.I pulled both plugs leading from tcase switch to the actuator and there was power coming from both to the actuator (thermal) but still no 4wd.At times there has been much gear grinding noise from tcase while trying to engage.Since the main drive shaft is routed through the tcase shouldn't there be some shaft turning in the case in 2wd? My next step is to pull the actuator and check for movement.I plan on changing it out anyway since the oem part is known for trouble.Any thoughts on the after market manual cable actuator available?

 

[buddyp]

Just got finished with latest round of investigation.The actuator has power to it and I had truck on jack stands,shifted to 4WH HI and all wheels hooked up immediately.I shifted back and fourth to both ranges and 2wd.A lot of grinding noises came from tcase while in 4 wd,I pushed the clutch in till the noise stopped and then only rear wheels turned in 4HI.I re clutched and shifted to 4hi again,had 4wd and the noises started again,confirmed by a helper to be coming from tcase.We noticed a large nut( about 1" in size) at the bottom of tcase directly under the tcase shift link.Could this be an adjuster of sorts?