Join Date: Jan 2004
Location: Battle Ground, WA
Sounds like what happened to mine two weeks ago. 1-2 upshift at 2500~3000rpm, rest were normal. I bought a code reader from obddiagnostics.com for $88 that hooks up to a computer. It returned code P0720- Transmission output shaft sensor failure. So I went and got a transmission output shaft sensor from the dealer ($17) and replaced the old one. Now its back to shifting like new again.
About the code reader I bought. Yes, you can get ones that are around $75, but they only read one protocol. That means if you bought one with the ISO protocol to read your Jeep, you could not read any GM or Ford's. With the one from obddiagnostics.com you can read all the OBDII protocols with a single unit. Schucks had a hand held scanner for $117 or you can also get scanned for free at AutoZone. I like self sufficiency!
The sensor was located in the tailshaft of the trannyand can be reached from the drivers side, just in front of the skid plate. I lost less than a cup of ATF during a quick switch.
So get that code read and go from there.
'98 ZJ 5.9, Deep Slate, 2" BB, 245/75-16 BFG A/T
'01 Dodge QuadCab Dually, HO Cummins, 6spd
'02 Kawasaki ZX-12r