98 Jeep Cherokee That Won't Upshift, Help!

[JeepJumper]

I just bought a used 1998 Jeep Grand Cherokee Larado with the 4.0l. 1st gear and reverse seem to engage and work fine but it simply will not upshift. Tranny oil is at the correct level, red, and does not smell burnt. I'm a car mechanic and just need some ideas as to where to look first.

Thanks for your help

[Chaoul1]

98's have a digital speedometer. Try doing the "key dance" by switch the ignition from Off-On, Off-On, Off-On and leave it on "On" the third time (Three times quickly) and see if any codes pull up!

Since you have a 42RE it might be the Governor Pressure Solenoid Valve. That's one of the main problems with these ZJ's from 93-98 on the 42RE Tranny's

[JeepJumper]

Thanks for the info. I probably won't get to it before the weekend, but I'm hoping you're right. Either way I'll let you all know what happens!

[erleep]

had the same problem with my 93 and i tought the trans was going out come to find out there is a plunger in the valve body that cracks and dont work right it is a 15.00 part but time consuming to replace as youll have to remove the valve body to replace it i did mine and i have not had a problem with it from that point on this is common with the 42re as well

[JeepJumper]

Just wanted to let you all know that I was able to fix 42RE transmission. The problem was the transmission output shaft speed sensor. It cost $50 bucks at the dealer and took 5 minutes to replace. I've been driving the Cherokee for the past two weeks now. Just thought you all would like to know.