My first diesel!!

[Philip]

The cruise goes throught the computer, but not the TPS

Would you like to explain where the TPS goes and what other processor the Dodge truck has that can take a voltage signal and convert it to a reading the PCM can use to allow upshift to OD.

 

[Greenleaf]

In my particular OEM FSm it lists the controller as having a very intricate part in the operation of overdrive/TPS function.



That's my manual... ... ... ... ... ... ... . others may vary. I'm not going to pull any wires from the controller to find out.



GL

 

[esamuelson]

I finally have narrowed down my od problem. I tapped into the orange\green wire at the trans for the overdrive solenoid and ran a wire up into the cab and hooked my volt meter to it. I found that with the key on, truck not running, in park, I had 12 volts at the wire. I then took it for a drive will watching the volt meter, at around 35 to 40 mph the voltage dropped to basically 0 volts. It looks like the trans is getting the signal but either the solenoid is bad or the is another problem with the od internally :{ I guess I am pulling the transmission now and will look into rebuilding and upgrading it. I did get the cruise to work though, the cable was not adjusted properly Its nice to know that all is not lost anyway.

I appreciate all the help you guys have given me in trying to resolve this problem!!

 

[Philip]

Did you wire in that reostat?



It sounds like it if you have cruise now.

 

[esamuelson]

I did not wire up the reostat, my old tps seems to be ok, it is just not physically hooked up to the motor. I just set the tps at about 1. 8 volts and clamped it there and everything seems to work, the cruise seems a little jerky and maybe if the tps was hooked up it would be able to read the throttle position and not overcompensate like it seems to be. Should I get the trans rebuilt or look at buying an upgraded one from someone? Any suggestions would be great!

 

[Philip]

Well the not going into OD could mean the solenoid could be bad. A person I know here had his 93 CTD A518 rebuilt. One week later the solenoid died. The person that rebuilt the trans borrowed my FSM to troubleshoot the system.



Locked at 1. 8 volts would equal about 1/4 throttle setting to the PCM.



The jerky cruise could be sticky linkage or the cable from the cruise head might be binding to. How much slack is in the end of the cable before it touches the throttle linkage. If the gap is wide it can cause a harsh engagement.



This is a new truck to you. Check the throttle linkage at the pump arm. If it has the plastic snap in sockets. Check them to see how loose they are. If there is much slop. Replace them. Dodge makes a replacement kit with steel rod ends and a new connector rod.

 

[RamAZ]

TPS and Cruise Control

I have been running a rehostat for almost a year now and not a problem. Cruise is rock solid, is not jerky and does not creep. Doing away with the TPS piece of junk was the best move I've made. I'm sure there a few out there that will disagree but to each his own.



I used a 10 turn, 1 watt potenometer to do the job and 3 conductor shielded cable to eliminate the noise. Total cost 20. 00 or so verses 169-200. I set it once and have not messed with it since.



Good luck.



Jim

 

[Paychk]

Would you like to explain where the TPS goes and what other processor the Dodge truck has that can take a voltage signal and convert it to a reading the PCM can use to allow upshift to OD.

Puzzled by your Q, not sure what you are asking? my post was in response to this inquiry:

I got the speedo fixed today but still have no od. I guess next I will check the voltage on the center wire on the tps and see what I get. Can someone tell me what color wire goes were or what function? There is no plug on my tps, someone soldered the wires direct to the tps and I am wondering if they wired it wrong. My cruise does not work, is that part of the tps or something different?

This is how I answered:

The cruise goes throught the computer, but not the TPS.



schematics here:



https://www.turbodieselregister.com/user_gallery/displayalbum.php?&userid=5777&albumid=678

I was just stating that the cruise isn't part of the TPS



Sorry for the long post

 

[esamuelson]

I did actually buy a potentiometer for this if the tps did not work. It is a 15 turn 1. 25 watt. I may still use that but was thinking that if all the tps does is basically adjust your od shift points why can't I leave the current tps set were it is and shift the od with the switch ( I would install the new shifter with the switch in the shifter end. ) Am I wrong in this theory?

As far as the cruise I set the cable so that it has about 1/2 inch of clearance at the throttle linkage. I do not have a manual yet, it is on its way, so I just guessed at this to prove that it does work and should be ok with some minor adjustments, hopefully!

Back to my trans problem, I am guessing the only way to know what is going on is pull the trans and tear the od apart to see if it is just the solenoid or something else. Is this correct? What for upgrades do you guys recommend? Is there someone that sells a heavy duty kit or a complete beefed up trans? I am figuring if I am going to pull it I want to do it right and not have to worry about it again.

 

[Greenleaf]

Thays everyones dream... . pull something off and rebuild it then never worry about it again. In real life it just won't work that way. Too many variables.



Some members do wire the TPS similar to how you described. Remove it from the pump, lock it in place and it sems to work fine. I have not tried it but others have and seem to think it works just the same.



GL

 

[Philip]

Puzzled by your Q, not sure what you are asking? my post was in response to this inquiry:

You should have quoted that question. To post that one sentence that the cruise goes threw the PCM but not the TPS might lead people to think the TPS goes somewhere else. I wasn't the only one that posted about that one sentence. It was missleading. You posted an answer. But didn't give anyone a reference to what you were talking about.

 

[cerberusiam]

Before you tear into the trans verify the OD works. You can bypass all the electronics and manually shift to OD by tapping the OD wire from the trans, running it thru a switch and grounding it. The OD solenoid is on the valve body so no need to tear OD apart to check it.



You should have a 2 wire connector on the trans driver side towards the back of the case and it will be pointing up. The heavier wire is 12 volt supply and should be energized with the key on. The other wire is the OD activate wire. Grounding it will engage OD if the solenoid, clutches, governor, etc are working correctly.



Cruise, TPS voltage, VSS, crank sensor, trans temp sensor all run thru the PCM. Bad components, bad connections, etc will cause intermittent or complete failures in one or more systems. Then the PCM could have a problem and screw one or all the pieces up. It sounds like somebody used the "slash and burn approach" to troubleshoot issues on your truck. I wish you luck getting it fixed.

 

[Greenleaf]

Cerb,



What's wrong with the "slash and burn" method? Works for me.....



It's similar to my book-keeping method, the "Pilot System" Pilot. Get it?

PILOT



Pil... ..... ot.....



pile it!



Never mind.



GL

 

[esamuelson]

The wire I tapped into the orange/ light green wire to test to see if the trans is getting the signal. It showed 12 volts with the key on and above 35 mph it changed to basically 0 volts which should mean that it got grounded and should work. I could take that wire and ground it just to prove it is getting a proper ground. If I dropped the trans pan and ground this wire can I see the solenoid work? Can you replace this without tearing the trans out and apart?

 

[Paychk]

You should have quoted that question. To post that one sentence that the cruise goes threw the PCM but not the TPS might lead people to think the TPS goes somewhere else. I wasn't the only one that posted about that one sentence. It was missleading. You posted an answer. But didn't give anyone a reference to what you were talking about.

Philip, Greenleaf I apologize for the confusion I caused. I will withdraw from this thread... I do not want to cause any distractions & wish it to remain on topic.

 

[cerberusiam]

Got it! PILOT... . pile it! Does that mean you have a PHD?



Pile it Higher and Deeper? :-laf





Now that the accolades have allocated... ...







That should be the right wire. The solid color should have 12 volts constantly and the PCM grounds the other wire to complete the circuit. On reflection you should see 12 volts when OD is off and drop to 0 when enaged as the ground is the path of least resistance. If OD doesn't engage it is something else internal to the transmission. The OD is on the valve body so it can be changed in the vehicle. You can't check physical operation of the solenoid installed but maybe can if it is off and voltage applied.



If OD still doesn't engage it could be a VB problem or the OD clutches and seals themselves.

 

[Philip]

You can't check physical operation of the solenoid installed but maybe can if it is off and voltage applied.

You can check it with the engine off and the key on. If you ground the wire you should hear I lite thunk if the solenoid is moving the valve assy. If it is moving then the problem will be in the OD assy itself. Sometimes the sound is so lite you need the trans pan droped to hear it.





Paychk no reason to drop out of the thread. All help will be appreciated.