1988 GMC sierra 2500SLE 4x4 not working? - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


GMC/Chevrolet Truck/SUV When starting new posts, please specify YEAR, MAKE, MODEL, ENGINE type, and whatever modifications you have made.

Reply
 
 
 
Thread Tools Search this Thread
Old 12-09-2010, 01:29 PM   #1
Junior Member
Thread Starter
 
Join Date: Dec 2010
Posts: 3
Thanks: 0
Thanked 0 Times in 0 Posts
X8BaLLX is on a distinguished road
Default 1988 GMC sierra 2500SLE 4x4 not working?

hi all just wondering if anyone has any suggestions on how to get my 4x4 working. the problem is that the differential will not engage to the front drive shaft when i switch to 4x4. the T-case engages with the drive shaft and the front drive shaft spins but it will not engage with the front diff?
X8BaLLX is offline   Reply With Quote
Old 12-09-2010, 01:38 PM   #2
Retired Senior Admin

Expert Gearhead
 
Danthurs's Avatar
 
Join Date: May 2006
Location: Sheboygan Wisconsin
Posts: 29,661
Thanks: 0
Thanked 16 Times in 13 Posts
Danthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to all
Default

This has auto engage on the front? Start with locating the wiring harness where it goes in to that area and start checking for any damage or corrosion.
Danthurs is offline   Reply With Quote
Old 12-09-2010, 01:57 PM   #3
Junior Member
Thread Starter
 
Join Date: Dec 2010
Posts: 3
Thanks: 0
Thanked 0 Times in 0 Posts
X8BaLLX is on a distinguished road
Default

yes it has auto engage in the front. i have already inspected the wires and it all looks ok there is no broken/bent wires and no corrosion. i jave also unplugged the connections and re plugged them in on the front diff? would i be able to test them with a volt meter?
X8BaLLX is offline   Reply With Quote
Old 12-09-2010, 02:21 PM   #4
Senior Member
True Car Nut
 
sawgunner's Avatar
 
Join Date: Jan 2009
Location: Dover, NH
Posts: 7,122
Thanks: 0
Thanked 0 Times in 0 Posts
sawgunner is on a distinguished road
Default

common failure in these is the actuator in the front differential. had this problem many times with my 93 chevy WT and my 97 GMC K3500. on the 3500 they replaced the actuator with the one from the electronic controlled 4WD (push button) and had to do some rewiring of the harness. after that never lost 4WD again other than when i snapped the front drive shaft
sawgunner is offline   Reply With Quote
Old 12-10-2010, 12:15 PM   #5
Junior Member
Thread Starter
 
Join Date: Dec 2010
Posts: 3
Thanks: 0
Thanked 0 Times in 0 Posts
X8BaLLX is on a distinguished road
Default

thanks for the replys. i believe it is the actuator in the front diff. i have looked into it and believe i am going to install the posi-lock instead. engaging the front end manually seems like the best way to go for me.
X8BaLLX is offline   Reply With Quote
Old 12-10-2010, 11:22 PM   #6
Junior Member
 
Join Date: Dec 2010
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Hawger is on a distinguished road
Default

There is a vacuum switch that engages the dogs in the diff. It is under the shifter on the floor. There is a vacuum line that runs from the intake to the switch and then from the switch to the diff. Check for good vacuum at the diff when you have the 4X4 shifter engaged and the motor running. If no Vacuum work back from there to the switch and the intake.
Hawger is offline   Reply With Quote
Old 12-10-2010, 11:27 PM   #7
Junior Member
 
Join Date: Dec 2010
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Hawger is on a distinguished road
Default

Did not read the other posts, got to scroll further.This is electronic, not the older vacuum system like I had.
Hawger is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
09 gmc sierra no 4x4 jamesredwood GMC/Chevrolet Truck/SUV 5 01-24-2014 02:28 AM
What size tire can I fit on a stock 2002 GMC Sierra 4x4 iowaGMC GMC/Chevrolet Truck/SUV 4 11-18-2013 01:25 AM
1999 GMC Sierra 1500 4x4 chevyman Introductions for new members 6 07-23-2013 07:03 AM
HELP! 1994 GMC Sierra 4x4 5.7L clsxtwo GMC/Chevrolet Truck/SUV 8 04-06-2013 02:53 AM
GMC Sierra gauge not working Britro GMC/Chevrolet Truck/SUV 1 10-01-2011 09:25 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 04:46 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.