1999 Dodge Ram 3500 Quad Cab - 2wd Cummins - automatic transmission.
I am having erratic speedometer issues and need the PCM pinout diagram/schematic to check the wiring.

Dealership won't give it to me. Say it's proprietary.
Both speed sensors check ok.

Any help greatly appreciated.

 

Did you check the speedo sensor on the diff

 

Yes, the rear diff sensor has the correct resistance and the pigtail has 4.9V and a good ground respectively.
The transmission output speed sensor pigtail reads 2.63V on both sides, (I believe it should be a similar 4.9ish Volts and a good ground respectively)so I feel there is an issue somewhere in there that needs to be checked for the full length of this sensor's wiring.

 

I'll look in my stuff at the shop tomorrow and see if I have them.. Please bump this up if I forget about it in the morning... I'm getting old...lol

 

No Specific Code? Like a P0720 or P0500 or Check engine light ?

 

Boy that must be a well kept secrete... I dont have anything in my stuff.

 

There are no warning lights coming up. I tried the ignition switch(on/off/on/off/on) to flash the codes but it doesn't work. Apparently 1999 is not the same as previous years for flashing codes.

Thanks Bob, any information greatly appreciated.

 

True, Not the same. I think you need a DRBIII to look at the PCM / TCM / ECM and or the CAN BUSS.
I looked over at the iATN site. But looks like the help is all over the place !!

 

Bob

After many hours, I found this site with good wiring stuff - https://mopar1973man.com/cummins/art...ing-maps-r469/

and a 2001 pdf service manual that gives the pinouts.

Can't believe how stingy the dealership's are forced to be.

Many Thanks for your time !!

Peter

 

Your welcome Pete.... No problem. Wish I could have found more.
My guess is that the problem is going to be the cluster OR PCM to TCM Communication problem.
But at least with the pin out you was looking for, you could of at least ruled out a broken wire or a shorted one with out too much fuss.
I do have alldata and onDemand... Let me know if I can help you with anything else.
Keep us posted on what you find...
Thanks
Bob

 

 

I did find some other pin out info. I didn't have time to look for specifics....

http://connectors.dcctools.com/home.htm

 

Drag Pak !!!! Hope you are well !!!! Did you get your truck sorted out?
How is the old Hot Rod Doing !!!!

 

Where did you find correct voltage and resistance trying to diagnose my speedo problem.