One problem related to transmission failure has been reported for the 1998 GMC Jimmy. The most recently reported issues are listed below.
Windshield wipers fail to actuate on an intermittent basis with no discernable pattern. Frequency of failure is increasing. When the wipers do fail sometimes they will activate after 15-20 attempts to turn them on. At times only stopping and turning off the ignition swithch and restarting the vehicle will get the wipers to activate. Transmission fbegan failing with occassional but noticable late and hard shifts from first to second gear . Engine light code scan indicated a failure of the valve body. Replacement of the valve body fixed the problem , but the addtional torque put on the drivetrain from the hard shifts most probably caused the failure of the rear u-joint as well.