MIL light came on in my 2001 Jeep Grand Cherokee 37K miles
I had just gotten off the interstate when I saw my Malfunction indicator light came on. Then as I accelerated from the light I noticed that it ran to 3500 rpms in first before it shifted to second (I wasnt gunning it or anything). I came out this morning and it did the same thing on the drive to work. The rest of the gears act fine, shifting at around 2500 rpm. I check my trans fluid and it was fine. I only have 37k miles on it. Any ideas what it could be? Thanks for your help.
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.
I am so interested in this very same tester. I was going to build my own, but have gotten side tracked. Glad to hear that it works well and you are happy with it. The tester you have just paid for itself, during that one application. Good job.
94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new
88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new