Erratic shifting 95 cummins 2500
 

Here was i got...
-1995 dodge cummins 12v 2500 4x4 47-rh auto tranny. Rebuilt tranny 25,000 miles ago. Just bought the truck last month.

The issue..
-at constant speed truck with either surge up 200rpm then return back. Or it will completly fall out of overdrive into 3 than back into overdrive. I have notice it way worse in cruise control. It will keep on acting up until i brake or accelerate. It usually happends at 60mph and almost every time around 64-67mph.

-what i have done...
Cleaned all grounds and have adjusted the kick down cable but the only thing that has done is change the speed in which the issue occurs. Lots of guys talk about possible tps, speed sensor, electronic noise, band adjustments, lock out switches, throttle body issues ect...
Just wondering if anyone has had identical issues/ or some guidence for a new mechanic. Also does the torque converter lock in 3rd and 4th? Or just 4th?
-thanks guys!

The tranny will go into lockup for all gears except 1st.
It sounds like you and I are experiencing similar problems.

Are the lights on the bottom of the climate control flashing at the same time when this problem occurs?
Do you have a cold weather cover on the front of the truck?

The problem is probably between the three wires that control lockup and overdrive between the computer and the transmission.

What your experiencing is a TPS failure ..going in and out of lock up and O/D .. change your TPS sensor ... easy fix. don't buy a cheepo unit .. they fail quick :argh:

The lights are not flashing on the climate control (that I know of) buy I will double check.

Also I live in california so really no need for a cold weather cover up in my opinion. The coldest it gets is around 40f.

I have been meaning to check the tps voltage. When you say cheapo? Napa quoted me $150 and mopar oem was $315- so no napa? Also woupd the tps have an affect even in cruises control?

Personally I would ditch the TPS all together and wire in a 10 turn 5k ohm potentiometer which will allow you to adjust when O/D and LU occur.

10 turn 5k pot [URL="http://www.amazon.com/gp/aw/d/B00C9O0MDK/ref=mp_s_a_1_8?qid=1447649774&sr=8-8&pi=AC_SX110_SY165&keywords=10+turn+5k+potentiome ter&dpPl=1&dpID=31YuJ3Pm9OL&ref=plSrch"[/URL]

Cutting the ends off a computer power cable gives you a nice, insulated, 3 conductor wire for you to run from the TPS connector to the pot. [URL="http://www.amazon.com/gp/aw/d/B006VKCFAQ/ref=mp_s_a_1_8?qid=1447649237&sr=8-8&pi=AC_SX110_SY165&keywords=laptop+power+cable&dp Pl=1&dpID=41j8rFZQzdL&ref=plSrch"[/URL]

Update
 

Took the batteries down to napa and had them check, turns out one was bad and the other haf such a low voltage they couldnt even test it. So i bought new batteries and went trough all of my grounds in the truck and scuffed them up and added some elctro-conductant lube. Problem didnt pop up as i drove maybe 40-60 miles the first day. The second day on my way to work in the morning it started to happen again. Its always worst in the mornings when its colder.

Can this be the temp sensor on the tranny? Also would i have any luck hooking a computor diagnosis ststem up?
Im going to instal a lock up switch this weekend and test the TPS

Try cleaning up all the ground connections, from batteries to block, and all the others in the engine bay. There are several. A bad ground will wreak havoc in short order. Hope this helps.

Thats what fixed it temporarily as i stated above. Although it came back a day or two after