My 4 wheel drive stopped working

Asked by Jul 15, 2014 at 08:42 AM about the 1990 GMC Sierra 2500

Question type: Maintenance & Repair

After struggling with the 4 wheel drive it stopped working. The last two winters the 4 wheel got cranky. If you shifted it in and out of gear it would engage, sometimes in low sometimes in high, now it doesn't engage at all. It is a floor shift so I would think it is mechanical, but the light doesn't come on either. I use the truck for field work so getting it to a shop is not a good option. I checked the fuse it is ok,,,out of Ideas is there an electrical connection?

2 Answers


There is an actuator on the front axle housing that has a tendency to fail, that is what I would check out. Mechanical selector should not just randomly select 4WD lo or high as there is a detent pattern it should follow, there could be a problem developing in the transfer case, most likely it will need an overhaul.

1 people found this helpful.

I ment to say sometimes the low works and sometimes the high works the low worked the best. I crawled under and saw 3 wires I think they might be for the actuator, will check those connections first

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