O'Neill

ok first off i have a 95 cummins 75 k miles reg cab long bed 410 gears 47rh no mods but a little plate profile change

the problem i am having is i will be going really about any speed over 40 and out of no where the tranny will unlock the converter then downshift out of overdrive into 3rd some times the tranny temp light will light up when it does it but not always

fluid temp seems to make no difference

i am confident that it is not internal in the tranny i feel its an electrical issue i had this problem when i first got the truck but i changed the temp sensor and it whent away for a little wile well its back and i have swaped out the temp sensor 2 times in the last 2 weeks thinking that was it

i am thinking that my TPS could be dirty and need cleaned? and that i need to pull the tps wires out of the main harness to eliminate the interfierecne but i find it odd that it whent away for about 2 k miles but now its back? i havent even towed anything with it either.......

please help me im really getting depresed about this truck it seems like its always something.......


Chris O'Neill
Events Coordnator
Purdue Off Road Club

j-fox

First , clean the TPS next, if it doesn't fix it put a filter on it. It is electronic and can easily be noise.

O'Neill

what do you mean put a filter on it? a inline noise filter? where do you get one how big does it need to be ?

CarlJensen

Do a search on TPS cleaning and adjustment. You will get enough reading to take a while to get through. When dirt gets inside the thing there is no predicting the way it will act. I forget who has the filter kit, but you should be able to find that info with a search. I clean mine regularly and long ago pulled the wires out of the original harness. Don't have trouble with it now and mine is the same set up as yours. I do not have the filter installed. Don't replace temp sensors until you have inserted a 1000 ohm resistor in the plug and driven it to make sure that is it. The resistor tells the computer the tranny is at 100 degrees to allow lock up and OD.

Dufrain

You can try slotting the holes in the tps to,it will come up in your search.you just file the mounting holes into slots so you can rotate the tps a small amount so you have some adjustment.Id do the resister in the plug and clean and slot the tps before you do anything else. It will only cost you a dollar.the resistors are at radio shack and a chainsaw file will do the slotting.

O'Neill

thanks im pulling the wires out and cleaning the tps today well go from there.....

Sidewinder

Try the 1000 ohm resistor in place of the temp sensor. Very easy to check and will eliminate any questions about the temp sensor. I did this first, (not the problem with mine) and then opened and cleaned the TPS which fixed all of my shifting problems.

I left the resistor in for the winter so I don't have to wait forever for the OD and Lockup to work.

As already suggested try a search, you should find more information than you can read.

infidel

Since you say that the temp light is coming on it is more likely a problem with the trans temp sensor than the TPS. Try the resistor trick.

O'Neill

ok little bit of an update i drilled the 1 16 th hole and sprayed the contact cleaner in and then sealed the hole drove it and it still did it but the temp light wasnt comming on still doing the same shifting pattern so i drilled a little bigger hole to allow for the tube of the cleaner to go in filled it with the spray worked the wiper arm again drained it as best as possible then refilled it and let it sit while i worked all night

got the resistors goingto put the tps back on tommrow afternoon and try it if thats the culprit great if not im going to throw the resistor in i have just been getting gp sorensen temp sensors at advanced auto are they no good? is there one out there that is much much better?

infidel

I would suggest if the trans temp sensor is bad that you leave the resistor in place and buy a real tranny temp gauge and forget the idiot light. Just install the new sender in place of the stock one.

Pop-Pop

I had a '92 that did just as you described. It was still under warranty so I took it back to the dealer. Kinda fuzzy about what they did but remember them saying that a switch had to be replaced. I'll bet that this is a well-known problem & with a standard fix.

O'Neill

i just installed autometer phantoms in my truck a couple weeks ago i have heard about ppl putting there guage sending unit there but it gets to the negitives here in indiana wont it hurt the tranny if i leave the resistor in place? i thought it was a built in saftey feature or something along those lines?

Dufrain

The cold wont hurt it Infidel has talked to the better trans builders and they assured him going into overdrive cold doesnt hurt it.He is in Montana and it sure gets cold there.Add the gauge and you will be all set.Its super easy on the 95 with the sender right in the line.The resistors are about 1.00 at radio shack

infidel

It is a safety feature if the tranny overheats but no big deal on the cold side. I wouldn't recommend jumping it with a resistor except to test the sender unless you have a tranny temp gauge.

O'Neill

thanks for clearing that up i will move my tranny temp sending unit to the line where the factory line is if the resistor trick works i have a autometer phantom guage on my a pillar now and i got the 1k ohm resistors today at radio shack im going to put it in tommrow and give it a whirl what is a normal opperating temp in the line right there what temp do i need to worry at?