Trans problem or "computer"

[Doc Holiday]

My transmission will not shift (hell it doesn't even hunt) into OD. The TPS is new. So I am thinking a sensor or the brains. Any ideas aside from buying a manual transmission for this one or a stick truck next time around. Which by the way is my solution to the issue from now on.

 

[TonyDenton]

check the trans temp sensor on the cooler line near trans . the early models were bad about that . or the speedo cable. sensor i would bet on temp see that a lot hope this might help tony denton TD,S transmission and Auto 30 yrs exp have nice day

 

[Doc Holiday]

I haven't checked either yet, but was also told of a sensor on the top of the trans what is it? The speedo works if that matters. I'll check tomorrow evening at work and let ya know. Can i remove the temp sensor and just wire the wires together?



Does the PCM have any control over the transmission?

 

[Not_Agn]

Check where the tps sits. The piece on the injection pump. I had a similar problem and had a shop replace the tps. It was actually this part on the pump that was worn out and had some slop in it. It just screws off of the pump. Lee

 

[Philip]

Check the RPM sensor. If it looses the RPM signal it will drop OD or not let it go in.



Pull the plug on the TPS and put some dialetic grease into it. Same for the RPM sensor.



What voltage did you set the TPS at?

 

[DPetrey]

i think i kinda have the same problem i have no OD and no speedo i have check the tps and used diealectric grease and still no fix i think the speedo sensor is bad it some how controls the pcm for shifting otherwise i am out of ideas

 

[Moab4x4]

The ECM signals the OD to engage. The TPS, transmission overheated sensor switch, speedometer (and probably the Crank sensor) give information to the ECM to control the timing of the signal.



One side of the OD solenoid is at 12V when the key is in the run position. Ground the other side with a switch and you will go into OD if the mechanicals are in working order. This wire is connected to pin 55 of the ECM controller. FSM says it is an OR/LG color wire. I grounded this wire with a switch under the dash when I still had the 518.



If that doesn't do it, check to see if 12V is on the other wire. If you have 12V on one side and grounding the other doesn't put you into OD then you have bigger issues than I can help with.

 

[hdm48]

FYI guys, the speed sensor does play a part in OD operation. If the speedo isn't working then it will never go into OD. If for some reason it still won't work after fixing the sensor, then you need to check iether the OD switch on the dash, the PCM, the trans temp sensor (just cut the wires and connect them together) or the plug on the TPS.

If all this checks out OK, then do a search and just bypass the whole sheebang and control it manually with a variable resistor. There are several guys here that have all the info on this subject.





Dave