[reekor]

Your transmission output sensor is bad or has a bad connection. There are two sensors on your model, an input speed sensor mounted to the front drivers side of the transmission and an output speed sensor mounted to the rear drivers side of the transmission.

Originally Posted by thejeepman

2000 Jeep Grand Cherokee Limited
6 cylinder (yes, a 6-cylinder limited)

My 4-speed automatic transmission went nuts on me today. Seems it forgot how to upshift to 2nd or higher. Tried manually moving the shifter to 2nd ... nothing. I took the RPMs up pretty high—almost redlining in 1st gear—but no upshift. I tried turning off the ignition and starting it again, but the same deal.

So, I drove the thing to a gas station in first gear ... 30 mph ... that was fun [I was on E of course]. I put in half a tank of gas and decided to drive home. Miraculously, it worked fine (although the check engine light was still on).

When I got home I did the old ignition trick to retrieve the error code. I came up with P0720. Here's what the research says:

P0720 (M) Low Output SPD Sensor RPM Above 15 MPH—>
The relationship between the Output Shaft Speed Sensor and vehicle speed is not within acceptable limits.

P0720 (M) Low Output SPD Sensor RPM Above 15 MPH—>
Output shaft speed is less than 60 rpm with vehicle speed above 15 mph (4-speed auto. trans. only).

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That's all well and good except the problem is that I have no idea what that means. Anybody experienced this before? Anybody know why there are two different descriptions for the same code? Any good suggestions on what I should do?

Thanks a ton.