97 Jimmy 4WD Problem

[Greedfly13]

Vehicle Specs:
1997 GMC Jimmy SLT...4.3 Vortec...4 door...4WD

Ok, I believe that I have something electronically wrong with my 4WD HI. About a month ago, I was driving a country dirt road at about 35 MPH, and I hit the 4WD HI button. The RPM's jumped really high and there was a loud whining noise that seemed to be coming from the front half-axles, and the vehicle became very hard to steer. The 4WD HI indicator light was on, but I assume that it was in 4WD LOW. The only way I could get in back in to 2WD was to press the 2WD button and then back up about 10 feet. Since then, I have tested it a few times (starting from a completely stopped position), and it has always emitted that loud whining noise and was tough to steer after getting the vehicle up to about 15 MPH...the 4WD HI actually did work normally one time, but after I stopped and repeated the process, it was again malfunctioning. This is why I believe it to be something electrical.

Now, I have only had the vehicle for about 6 months, and I had never previously put it in 4WD LOW, so I am not completely sure if my speculations are correct. I know that it is only supposed to go into 4WD LOW if the transmission is in neutral and you going less than 3 MPH, so again, I really need some help here. Have you ever encountered this problem before, and is there any advice/information you could give me to help? Thanks again for your time, and I really appreciate it!

Blake Gibbs

[modification_inc]

Are the tire sizes the same on all 4?

[Greedfly13]

Yes, all 4 tires are 235/70...but how would that have anything to do with the problem I am having. It rides completely fine when driving in 2WD Low. Thanks.

[vinnie97]

its going to be tough to steer. both front wheels want to turn at the same speed. Only use your 4WD on snow or sand when you have no traction. DO NOT use 4WD on pavement or anywhere you have traction.
Doing so will ruin your front axle.

[Greedfly13]

Yes, I understand that 4WD is only supposed to be used in off-road situations...again, I believe that the hard to steer feeling I am experiencing is due to it being in 4WD LOW...my problem is that I can't get the vehicle into 4WD HI...