Wrecked truck repair 21 6.7 Ho, no tcm pcm communication?

[lugnuts124]

Looking for some help
Have a Wrecked 2021 6.7 HO was hit hard in left front
Battery was shorted, fuse box smashed
I have replaced the fuse box with same exact part number
Inspected left dash hanress(this is main harness on left side of truck from dash to fuse Box I had a couple damaged wire that i repaired near the fuse box plugs

I’m thinking I have communication issues, can bus issues?

Truck turns on but the P flashes and it’s says not in park. Then it say something about continuing to drive truck may not restart.

When I try to connect to tcm/pcm with jscan it fails
When I connect to bcm it’s successful

Other things to note.

Power steps are not functioning
Truck goes right to run when you push button. One time I got it in ACC mode
The

Shifter interlock in column won’t release

Radio is locked i don’t have code

Piles of error codes when I scan

I checked all connections multiple times and I checked grounds


Basically need to know how I can start proof testing can network or individual modules

Willing to pay for help/software/hardware/wire diagrams

 

[H3LZSN1P3R]

@Jimmy07 may be able to help.


Have you made sure there are no damaged harnesses anywhere?

 

[lugnuts124]

I shot him a message
I had some damage on the one harness at fuse box connections and i carefully repaired it all. If I can’t find a way to pinpoint issues I’d consider replacing that harness but it’s expensive and the whole dash needs to be removed to replace it

 

[HarryN]

Look at the can bus and star connector connection setup.

Things can look ok, but still not be functioning correctly.

Here are some example videos.

https://www.youtube.com/results?search_query=ram+canbus

 

[HarryN]

Here is a thread with a repair going on with a few things that might be helpful.

Thread 'Flooded 2023 RAM 2500'

Dec 17, 2024

I neede an HD truck and they are very expensive lately. I live in Alaska and everything is even more expensive here. So I decided to go this route. I bought a flooded truck and my friend found a shop in Houston who was willing to try to make diagnostics.

It is really nicely configured truck and I really hope I will manage to get it restored. I wanted to ask if anyone knows a way to connect to the main modules (BCM or ECU) separately to test them as the shop guys still can't get any communcation with the truck trough OBD. I am wonder if there are fuses that blow first. I know it cpould...

• rauan
• Replies: 52
• Forum: Modifications and Accessories

 

[lugnuts124]

Thanks for that info
I tested voltage on can high and low and they are 2.6 and 2.5 with everything hooked up
Im gonna test resistance now

 

[lugnuts124]

109ohm at dlc with bypass cable installed

 

[lugnuts124]

60ohm if I measure on the original pins I pulled out of dlc

 

[lugnuts124]

Appears can system is operating and I have communication out of bcm and rf hub. Seems as if everything is looking for tcm and ecm communicating and not getting it. I guess I need to check for power at both units? Not sure where to look anymore

 

[HarryN]

Thanks for that info
I tested voltage on can high and low and they are 2.6 and 2.5 with everything hooked up
Im gonna test resistance now

I don't know what the numbers are supposed to be, but that seems like too little of difference to work.

Here is a plot of can signal voltage from wikipedia.

CAN bus - Wikipedia

en.wikipedia.org

and the main article.

CAN bus - Wikipedia

en.wikipedia.org