98/99 Cruise control

[svoking]

hi guys this may or may not be in the right place for this post i was trying to get it in a forum that will get traffic by those well versed in the wiring specific to 98-99 trucks.  

i have a 98 ram that the CC will not turn on. the light on the dash will not turn on and attempt to work.

this is not a very standard truck.  the build is..

-1998 ram 1500 4x4

-4bt

-nv4500

-98 MT PCM

-98 cummins MT engine and transmission harness

-99 2500 cummins frame, under hood and in cab wiring harness 

-99 2500 cummins interment cluster.

CC is the only thing not working i can jump in her and it starts and runs like a 12v truck. no CEL, tach, odometer, speedometer, fuel level, engine temp, and volt gauges all work correctly.  
i cant find any wiring in C130 at PDC that is causing a problem.  CC signals are getting from the steering wheel controls to the pcm (c3 pin 11).  The CC circuit from pcm through brake switch to CC actuator is complete with foot off the brake pedal and opens when pedal is pushed.(pcm C3 pin 11 to CC actuator pin 3) speed control supply on pcm C3 pin 11 will only produce +12v when I actuate the CC vacuum/ vent circuit using my scan tool. The best I can tell the pcm is un happy and will not turn on CC.  am I missing something on the 98 12v side? I know the vac brake trucks had a vac sensor that turned on the brake light but I didn’t think hyd boost trucks used this sensor?  There are no codes in abs module either.

I have 3 symptoms that I under stand are unrelated judging buy replies on a previous posts on there pages.

-p1765 was told this is not going to stop CC any impute on this code?

-p1388 I have gotten this intermittently recently but CC still doesn’t work even when its cleared.
-seat belt light comes on after engine is running and will not shut off.

 

I’m pretty disappointed I drove this using 99 under hood wiring for an at with a at in it for 12 years with the ecm flopping around and every thing was working before buying a southern truck and swapping to the MT and MT wiring during the resurrection proses.

[Great work!]

First Try checking the brake sw signal at PCM C3 pin 24.

 

The auto tranny has a park/nuetral signal at  pcm  C1 pin 6 on MT truck that wire is grounded all the time. AT is grounded only in park or neutral.  Maybe your PCM is setup for the AT.  See if the connector has a wire and pin for that. Try cutting it if it does. Look at the old harness too.

 

If that doesn't help then I suspect the dodge ECM for the 24 valve has a specific message on the CCD bus that the PCM is looking for to enable the CC.

[svoking]

hmm i did not check C3 pin 24 i didn't think at was part of the CC, but ill check it to make sure its working. 

 

as for the pcm ecm ccd bus its a 98 pcm as stated so no ecm. i did confirm 98 pcm is for an MT and engine/trans wiring is for an MT.  It doesn't set any AT trans codes either.

i do have another pcm, it is a 98 AT 12v can the AT functions be fooled to make CC work with that pcm? i still wonder if code p1765 is the culprit.. 

[Great work!]

Are you using the PCM as stock for an alternator voltage regulator or do you have an external voltage regulator?

The alternator field circuit and auto trans relay are both turned on when the engine RPM is running. 

[svoking]

i am using pcm as 100% factory controller for everything.

i know its the same circuit but being an mt there is no trans relay wired into the harness. 

[Great work!]

It's odd the PCM has a code for the trans relay if it's a manual. Maybe wire on in temporarily.  Maybe some member on here has a manual truck and can check if the relay is installed.

[svoking]

the output from pcm to the trans relay is used on an MT for the 12v+ to the alternator. its shown in the 98 wire diagram. 

i would love to find someone in my area of wi i could just plug my pcm into there truck and see if its the pcm its self. 

[svoking]

so i checked the c3 pin 24 for brake sense. it is grounded with foot off pedal and then 12v when pedal is pressed. 

[svoking]

On 8/10/2024 at 10:06 PM, Great work! said:

The auto tranny has a park/nuetral signal at  pcm  C1 pin 6 on MT truck that wire is grounded all the time. AT is grounded only in park or neutral.  Maybe your PCM is setup for the AT.  See if the connector has a wire and pin for that. Try cutting it if it does. Look at the old harness too.

thought i would mention this, my mt wiring dose not have a pin populated in the pcm at all, i also have a 98 v8 mt pcm and this pin is not populated in it either. so in 98 an mt just did not use it?

dose any one know what the abbreviations on this diagram stand for? I'm not sure what there in reference to and i am trying to check compatibility of components on the ccd bus. also on a 98-99 ram what is considered to be the bcm? there's not to many modules on these trucks and I've not run into one being called a bcm. 

i figured out the seat belt light was on because the srs module is different between a single cab and a quad cab. swapped them and took care of that light. 

[Great work!]

So looks like the 98 must not use that pin.

You are using a 98 PDC and wiring for a 12 valve? Or is that part of the 99 2500 wiring left behind? Study the pins at the connectors where the truck harness plugs into the engine harness. Also look at the old harness for the AT. Are there any extra or missing wires? Do all the pins have a mating pin in the plugs? Is there a connector that went to the AT harness that's part of the truck harness not engine harness? If so plug the old AT wiring in that went down to the tranny.

 

I Don have a 1998 12v wiring diagram can you post a link to it?

[svoking]

1 hour ago, Great work! said:

You are using a 98 PDC and wiring for a 12 valve? Or is that part of the 99 2500 wiring left behind?

 

I Don have a 1998 12v wiring diagram can you post a link to it?

so the way the harness is laid out is like this, starts at pcm runs to engine and trans then over to PDC. both the 98 12v and 99 24v are designed this way. the difference being the 24v adds the ecm but is wired to every thing else in the same manner. essentially what i did was install a 98 12v MT pcm and engine harness in a 99 24v AT truck.

ive been looking for something i missed in connectors c1 c2 c3 and c130 (pcm and pdc, the only 4 connectors really involved in the swap), as far as what they do on one year versus another and they are very similar. 

 

the 98 service manual is a bit tricky with the wiring, the first set of diagrams are 12v, if you are searching the pdf and end up near the bottom of the page(page 1931 and up) you are in the supplemental 24v diagrams.  and now that im looking at this is not the 98 document ive been using apparently i have saved two and the other wont upload though it looks the same.

 

im suspect a compatibility issue on the ccd buss the PCM "logic"  seeing something it doesn't like, or its not seeing at all. but i cant figure out the acronyms for the ccd modules are so im not sure what's actually talking on the ccd to start looking at that end of things.  i can email you any manuals you want for the second gen you want is this doesn't post right. 

1998 Dodge Ram Wiring Diagrams.pdf

[Great work!]

Thanks for the diagram, it's kinda a catch all with gas, 12 valve and 24v AT and MT all thrown together. It's confusing. 

 

I did some checking on my truck 1999 24valve auto. I have a special stand alone vp44 system. No ECM is present ( long story ).

 

My CC light won't turn on with key on engine off. It will turn with engine running. The CC works fine without the CCD from the ECM. It disengages when shifted to neutral but light stays on.

 

My CC works with the trans relay or the ACD relay unplugged.

 

At C1-6 PND I get 0V in P and N. 12V in D.

 

At C3-32 CC switch from steering wheel I get 4.7v nothing pressed. 0.93v on/off, 3.5v set. 2.86 coast. 4.18 accl. That's back probing with all 3 connections plugged in and key on.

 

I hope this helps.

I don't remember how the clutch affects the CC on a MT. It either speeds up or disengage. 

[svoking]

9 hours ago, Great work! said:

Thanks for the diagram, it's kinda a catch all with gas, 12 valve and 24v AT and MT all thrown together. It's confusing. 

 

I did some checking on my truck 1999 24valve auto. I have a special stand alone vp44 system. No ECM is present ( long story ).

 

My CC light won't turn on with key on engine off. It will turn with engine running. The CC works fine without the CCD from the ECM. It disengages when shifted to neutral but light stays on.

 

My CC works with the trans relay or the ACD relay unplugged.

 

At C1-6 PND I get 0V in P and N. 12V in D.

 

At C3-32 CC switch from steering wheel I get 4.7v nothing pressed. 0.93v on/off, 3.5v set. 2.86 coast. 4.18 accl. That's back probing with all 3 connections plugged in and key on.

 

I hope this helps.

I don't remember how the clutch affects the CC on a MT. It either speeds up or disengage. 

thank you that's good information to have, i will check those inputs as soon as i get a chance. 
I'm really surprised the cc works with no ecm talking to the pcm but that's good to know. 
 

i have to ask do all the gauges work on your instrument cluster?

[Great work!]

20 hours ago, svoking said:

thank you that's good information to have, i will check those inputs as soon as i get a chance. 
I'm really surprised the cc works with no ecm talking to the pcm but that's good to know. 
 

i have to ask do all the gauges work on your instrument cluster?

No I'm working on a custom ECM

[svoking]

On 8/24/2024 at 2:09 PM, Great work! said:

At C3-32 CC switch from steering wheel I get 4.7v nothing pressed. 0.93v on/off, 3.5v set. 2.86 coast. 4.18 accl. That's back probing with all 3 connections plugged in and key on.

thanks for posting these to compare to, mine are the same at 4.7v, 0.93v on/off, 3.49v set, 2.86 coast, 4.17 accl. 

so last night I went and tried something kind of wild, I pugged the old 99 pcm into the 98 engine harness with no changes to it.  

key on engine off no cc, key on engine running the cc light will turn on in the cluster. this light wont even turn on with with either of my 98 12v pcm's AT or MT. 

now the 99 pcm will not set a target speed but my tach is not working, i have no tps signal and pin c1 6 is not populated so i wouldn't expect it to fully function. 
it looks like the 99 would probably run cc if i wired the c1-6 but that would leave me without my instrument cluster working and that would defeat the purpose of what im trying to do.

sense 98 and 99 are clearly different i wonder if the 98 12v AT pcm needs to see 12v at the c1-6 pin before the cc will even turn on the light.  i may try this with the 98 AT pcm next. given the  98 12v MT pcm is setting that p1765 code im not sure i trust it is functioning correctly internally, but the AT pcm only sets trans codes so every thing engine side seems good.  

[Great work!]

Do you have a 98 instrument cluster to try. The CC light is turned on by the CCD bus. Unlikely but maybe the command structure is different. 

 

I always wondered about the CC on manual trucks. Seems like the motor would Rev away when the clutch is pressed. Maybe the diagram has something missing about the clutch switch. Maybe someone will chime in that has a manual. 

Do you have good vacuum at the servo?

 

[svoking]

i have a 98 gas cluster that i have installed and tried, it dose exactly the same thing as the 99 one dose, even the tach works correctly.

vacuum is good at servo.

 

from what i read in the service manual cc is canceled when the engine rpm increases to rapidly on all engines, and this is how it is canceled if the clutch is pressed. 

perhaps i should switch out clusters and see if the 99 pcm turns on the cc light of the 98 that will tell me if the ccd signals are the same.

[Great work!]

I think the earlier trucks like 1997 had the CC light in the steering wheel switches instead of the cluster. But a very different PCM.

 

Do you have the clutch safety switch hooked up or bypassed?

[svoking]

clutch safety is bypassed, just left the jumper wire in the cab as i didn't have a safety switch i to install. 

[Great work!]

Interesting read, but just adds to confusion 

https://www.turbodieselregister.com/threads/clutch-pedal-safety-switch.258150/

 

Some say it causes problems others say not so. There may be more going on with the clutch switch it is an expensive part so maybe it's more than a simple switch.

Maybe your PCM doesn't have CC it could've been a stripped fleet truck or had it programmed out.