1988 1500 no 4x4 question

[02suburbanZ71]

My friend has a 1988 1500 with 288K miles. He puts it in 4x4, you hear it engage, the front drive shaft turns but it will not send power to the ground. He checked the wiring and all looks good. We think its a problem with the front diff. Any ideas?

[Jsdirt]

You can have someone work the 4x4 while you watch the actuator. If not working, check for vacuum leaks first. Check the vacuum switch in the transfer case - make sure it's sending vacuum to the actuator when in 4x4. If that's all set, then it could be a busted cable. IF the cable checks out, your last chance is the unlikely chance the cable came unhooked inside the diff - if that checks out, now you've got to go digging in the diff.

 

Shift into 4x4 with engine off - see if you can spin the front driveshaft. If you can spin it, you've got a transfer case problem. If you can't, good. Now put it in 2x4, have a buddy squeeze the actuator so as to yank in the cable, then spin the front drive shaft. One or both front wheels should turn. If nothing, check the cable and go from there.

 

I'm at this stage with a '89 S10 Blazer that I've been throwing money at for the past 4 years ...

[02suburbanZ71]

You can have someone work the 4x4 while you watch the actuator. If not working, check for vacuum leaks first. Check the vacuum switch in the transfer case - make sure it's sending vacuum to the actuator when in 4x4. If that's all set, then it could be a busted cable. IF the cable checks out, your last chance is the unlikely chance the cable came unhooked inside the diff - if that checks out, now you've got to go digging in the diff.

 

Shift into 4x4 with engine off - see if you can spin the front driveshaft. If you can spin it, you've got a transfer case problem. If you can't, good. Now put it in 2x4, have a buddy squeeze the actuator so as to yank in the cable, then spin the front drive shaft. One or both front wheels should turn. If nothing, check the cable and go from there.

 

I'm at this stage with a '89 S10 Blazer that I've been throwing money at for the past 4 years ...

Thanks maybe i can try this tomorrow!