Auto transmission Searching for Gears...

[DeanP]

Hi folks,

I've got a '93 D250 Cummins LE 2wd with the 4-speed auto transmission and with 105k miles. I need help dissecting a possible transmission problem. A lot of times when I'm cruising on the highway (on level ground and empty) at a steady 45-50 mph, my transmission seems to shift (or search) for gears between 3rd and 4th. My truck does not have a tach, so I couldn't tell you what the rpms are showing. So, is this a problem with the transmission itself or maybe just the torque converter? How long do these trannys last before a rebuild? Any help would be great and thanks...

 

[EWalshak]

This may sound simple, but is the fluid at the right level. I have a 94' gas burner that has basically the same trans but with lockup and it does that if the fluid gets low. Unfortunately I am rebuilding it as we speak. They are not that hard to do. I may be doing a rebuild post on it with photos for the people that have never been inside an auto trans before.

 

[dodgenstein]

Sounds like the common symptoms of a throttle position sensor (TPS) problem. There are many threads on cleaning, adjustment and replacement of this.

 

[cerberusiam]

TPS, speed sensor, CPS, or even ground problems can all contribute to the OD hunt issues. Generally its TPS wear or adjustment, or, the speed sensor.



To rule out the trans you can tap into the OD sense wire at the trans connector with a switched circuit to ground. Ground the circuit and OD will apply and should stay even at a stop.

 

[JLEONARD]

Definately sounds like the TPS needs adjusting.