Code P0720

From: david.clement@verizon.net
Date: Sat Jul 10 2004 - 08:27:48 EDT


Yesterday on the way to lunch the check engine light came on. I plugged in my
scan tool and got P0720. Cleared it a couple of times but it comes right back.

Truck runs fine but the shift points at light throttle have moved up a few
hundred rpm's (which actually seems to be better for performance). FWIW, 99
3.9l v6, 42RE tranny.

Anyway, the FSM states that P0720 is a descrpency in the output of the
transmission speed sensor and the vehicle speed sensor or that the transmission
speed sensor output is less than 60 rpm when the vehicle speed is more than 15
mph.

I have cleaned the connections on the output speed sensor but the code still
comes back.

Questions:

1. Before running out and picking up another sensor is there anything else I
should check?

2. If this sensor is not working or is giving erronous readings will that
account for the increase in light throttle shift rpm's?

3. Is this sensor the same for all Chrysler products that use the 42RE series
tranny (my son works for Jeep now and I would like to take advantage of his
discount if I can get it through him)?

Thanks as always,

Dave Clement
99 SLT+ CC 4x4 3.9l v6



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