I have a 93 d250 cummins that recently stopped shifting smoothly into overdrive and started dropping in and out of overdrive repeatedly. I found information on this site on how to test the voltage with a multi-meter and paper clips. I tested the TPS and i am getting the correct amount of voltage, i cleaned it and it still drops in and out of overdrive. Is there anything else i should be doing or looking into? Thanks

 

Are all your connection good down at the tranny?

 

Yes they are i double checked, and i cleaned the shift down linkage for the transmission.

 

Here is something you can try for testing I work on windmills and we have to testing for similar problems im not sure if your multi meter has this option I know on fluke meters they do ok so get your meter to hook inline with the wires at the tranny turn on the min max on your meter and drive around have a friend watch the meter to see the readings (your driving hard to watch the meter and drive) find that loss of power then when you do go back on the wires to the next component and drive and test again keep testing back from till you find your point B (point A would be your tranny) sometimes old wires can look like they are fine from the outside but a sipple bump in the road can loose that power (drop a gear) I hope your following me on this I know problems like these can rack the brain and loose sleep over about but so when you find your point A to B you can find is it the power to the tranny from the tsp or tps to the main power it doesnt take much to have things drop power for a few seconds. Good luck man I keep checking every day back to see how this is coming

 

Okay i will be sure to give that a try, i cleaned all of the wire connections on the transmissions, i had it in the shop sitting for the last couple days at 70'f which is above the minimum temperature for the coolant switch, which i thought might be the problem. I took the truck for a drive and it hit overdrive right away and stayed in, i stopped at a light and when i started taking off again it dropped OD twice and then stayed in again.

It seems to be speratick, before i touched anything last week it would always hit and drop out right away, but after i cleaned the connections and tested the TPS it seems to be some what better but not perfect

Any suggestions? PCM maybe? or worn clutch bands in the tranny? Thanks.

 

Does it drop a gear when you hit a bump or a turn in the road cause it sounds more electrical to me then anything

 

No it doesnt do that at all, like i said it seems to drop it occasionally when driving, tonight it shifted into overdrive and stayed in the first time when the motor was cold. But sometimes it will drop in and out no matter the temperature. The previous owner used it as a toy hauler to bring a fifth wheel down to Florida every winter and he had countless wires running off the battery to all parts of the truck, so in that respect it is an electrical nightmare to try and find the problem.

 

Well that aint no good

 

Replace the transmission temperature sensor. I had the same problem, Dodge tech said it was TPS. Bought a $350 tps, put it in, same thing. He then hooked up the scan tool and found the controller was seeing the trans temp jumping everywhere. Dodge designed the trans to not go into overdrive until the coolant temp/ trans oil temp were above "x" so they became "emissions compliant" sooner. I'll bet that's your problem.