Computer geek/IT Student
Join Date: Jul 2010
Location: Upstate NY
ComputernerdBD is offline
Re: 98 blazer 4 wheel drive no releasing help !!!
Just got back from my local transmission shop. I was wrong saying the vacuum canister only engages in 4 lo. (I'll have to reread my owners manual.) My Jimmy is still stuck in 4 hi but the tech at the shop disconnected the vacuum hose at the tee up the line a few feet and plugged the hose with a golf tee. This disconnected the front axle from the drive line. The transfer case is still engaged but is not driving the front axle. Have to drive to Detroit tomorrow and he said this will al least get me down the road with no damage but my fuel mileage will suffer. When I have more time, will out her into the shop for repairs. He believes that the "motor" is frozen, giving the signal it is stuck in 4wd, thus, not releasing the vacuum on the canister.
Are you sure the transfer case is still engaged with it in 2HI? Grab the front driveshaft and try to rotate it to be sure. If it is free, your problem might be the vacuum switch on the transfer case that activates that actuator. 98 3-button setups have a switch on the transfer case. Cheapest thing to try. Look in the HELP! section of Autozone. Replace it and cycle it through all of the modes (but wait about 10 seconds between shifts). If it works, you might have just solved your problem.
If it is locked (or you can't get it into 2HI), it might be your encoder on the transfer case (likely) or the computer (less likely, but common). Also check the ATC fuse under the hood. I once got it stuck in 4WD and it was the ATC fuse. GM dealer put a 10A instead of a 20A to try to defraud me. Also try pulling the 4WD fuse for about 10 seconds to reset the system. If it works, it is electrical (TCCM (computer) or the encoder). If it is engaged, in 2HI and the encoder is working (going through all the modes properly), you might be looking at an internal transfer case problem.
1998 GMC Jimmy 4.3L/4L60E/NP233 SLT
Mods: Fog Lights, eBay Eurotails, Spectre Cold Air Intake, B&M transmission cooler, deep trans pan, interior LEDs, Posi-Lok