Engine/Transmission (1994 - 1998) Torque Converter not locking up...

[moremph]

We're working on a '96 2500 4x4, and cant get the torque converter to lock up and it's shifting too early under Wide Open Throttle.



We installed a built Sun Coast trans. and tripple disk converter and a ATS billet flexplate about two weeks ago. We'd like to take care of the problem on our own, but we will contact Sun Coast if we have to in the near future. After instalation we noticed the upshifting too soon and on highway driving the TQ would only lock up under acceleration. Normal cruising it stayed unlocked. Now we cant get it to go into lockup at all. Also, under normal driving it shifts exactly where its suposed to. Under WOT, it winds out 1st gear nicely but the 2-3rd gear shift is waaay too soon. And as soon as it shifts into drive it goes into OD.



We have reset and let the TPS "find" itsself and adjusted the T. V. cable a few times. Today I tryed driving it with the TPS unplugged and it would not shift into OverDrive. We removed the TPS and tested it with a multi meter and got very sparatic voltage readings through it. As you would turn it the voltage would fluxuate up and down throughout the range of motion.



The computer had a code #24. wich is a TPS high voltage code. but that was after I tryed driving it with it unplugged. Tomorrow I will clear the codes and try it again. I priced a TPS at a local parts store today at $200. no thanks. I will install a potentiometer if I have to, but only if I have to.



Where should I go from here?

Try making a mystery switch?

Check the speed sensor?



Thanks in advance for any insight or help.

 

[Jim Fulmer]

If you get a TPS get it through Cummins if you can as it is allot cheaper. The TPS voltage deal is a PITA and I have had my rounds with it also. Install a lock switch as you will want that anyway and it is a backup if you do have to drive for a distance with it throwing a fit.



The transmission deal sounds like stack shifts..... nothing new for a 12V but it is curable with springs and line pressure... ... . 2-3 hang shift at WOT is another one for a 12V.



If you have the Gov springs too tight or too loose it affects the angle that the linkage is in based on how much the idle screw is up or down. I know this thought is out there but it does matter. Check your linkage adjustments and set them IAW the service manual.



Jim

 

[zstroken]

Sounds like the TV cable is not adjusted right or a bad TPS. I have my TV cable set on the tight side to get the shift timing like I want it. The pattern my converotr locks and unlocks is unique, but it is worth it for the 3600RPM WOT shifts.

 

[moremph]

Thanks guys.



Jim, We did just put 3K gov. springs in it also. I guess that is something else to check, good call.





I have found instructions for wiring a lockup switch on a few diffrent sites. I believe it is Pin 54 (orange with a black tracer wire) that needs to get tapped. Problem is I dont know where pin 54 is. Can anyone tell me wich one of the three connectors it is in and kinda where it is located on the connector.





Thanks again gang!

 

[Ridesamule]

If that 96 is an early model I would get the flash done before trying a mystery switch or you are just inviting more agrivation in to the mix.

 

[Howard Durand]

If your TPS is giving you erratic voltages as you turn it. It is doing you more harm than good. You found that removing it completely doesn't work. Try removing it from it's mounting but leave it plugged in. Tie it up out of the way and drive the truck a ways. You will have a constant low voltage from the TPS but the results should be similar to what Ridesamule gets from his scheme. You could change the voltage by locking the TPS at different points of it's rotation with a bent piece of metal and a small "C" clamp. The thing only rotates about !/4 turn.

I have done the same thing except I have a pot. in the ground leg of the TPS that I can adjust. The TPS just hangs there.



I think the information you are reading about the lockup switch is for the 94 & 95 trucks. At least the 94. They only have one PCM and it's connector has 60 pins.

Later models use a different setup.

 

[Joe G.]

If you have an early '96 the PCM programming is not right. You need the reflash before doing anything else. The part number for it is 04886926 just in case you get some static from a Dodge dealer.

 

[moremph]

FINALLY!



we have it locking up now. I messed with it for a few hours today and finally broke down and wired in a Potientiometer. Went for a drive and you can adjust O/D shift and lockup where you want. Its pretty nice actually.



I could only find a 5k Ohm Pot.

Will that be allright, or will I get a High Voltage TPS code?





The 2-3 and drive to O/D under WOT shifts are still way too early.

Im starting to think its a valve body issue. I may call Sun Coast tomorrow.



Thanks to everyone for all the advise.

 

[Howard Durand]

Good to hear it is working. Don't worry, there is no danger using a 5K pot. It actually presents less load on the 5 volt supply. It seems that the readily available pots are 2k and 5k. I have a 5k single turn pot and plan to do the same thing.

You might get a high TPS voltage code if you turn the pot too far toward the 5 volt end. If you mount the pot where you can adjust it, mark the point where you get 3. 5 or 4 volts and don't advance it any further than that. That should avoid any high voltage codes.

As to the early shifting, the TV cable may be too tight. As I remember, Bill K suggested having about 1/8 inch of travel left in the TV lever when the accelerator is fully depressed.