95 cummins auto trans problems.

Hurley

Hurley

WTFab
Joined
Feb 22, 2008
Location
Statesville
So I have just purchased a 95 cummins 2wd with auto trans. Truck has 187k miles, I've no clue on the history of the trans - whether it is original or not. Currently the trans fluid is at an acceptable level and quality. I've only driven it about ~60 miles.

The problem is the inability of the thing to shift to overdrive and then stay.

Shifting into OD generally takes a nearly full throttle application, resulting in a shift point around 2300rpms. once it's in OD, it will drop back to 3rd - regardless of throttle position, road grade, engine load, vehicle speed. Then it will shift back to OD, and the cycle will repeat soemtimes as frequent as every 5 seconds, and sometimes I can travel a mile before it happens.

What is wrong?


- Joey
 
I need a little more info to be helpful. Do you have acsess to a scanner with a data display? I would like to know if the computer is commanding OD or if it is cycling it on or off.

Could be overdrive solenoid, or bad seal on the overdrive pistion in the trans, bad computer, valve body issue blah blah.
 
I had a similar issue with a Mazda. It ended up being some solenoid on the trans that was acting up. Replace it and the trans lasted another 6months before it completely died
 
I had a similar problem with my 02 cummins. Turned out I had a bad shift solinod and low line pressure. It was actually pulsing, the diesel tranny shops new what it was when I talked to them. The line pressure is low in OD and since the governor watches for pressure signals, throttle position and speed and few other inputs it was commanding the trans to lock/unlock back and forth a constantly at 45-50 mph at 1/4 throttle or less. It ruined my stock converter to. I put a dunrite VB in it and new shift solinods as well as adjusted the bands all at once and then put the TCS triple disc TC in the following weekend. It made a huge difference and fixed the problem completely. If yours is not staying OD you need to take it and see if the trans is being ordered to shift out of OD or if it is a mechanical failure allowing it to just fall out.
Good luck.
 
^thanks for the info. I had sent mysterync a pm and received some info/TSB's as well. Now it's time for to check out what's up.
 
Drained the pan, new trans filter, and adjusted the band torque.

Finally did some diagnosis and found that the TPS is bad. .24V with it unhooked from the throttle assy (to test). Rotating it yielded an immediate voltage jump to ~4.5, then a slight drop to the high 3's at stop.
 
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