Hi all,

I am sorry to start another thread about the stupid "no bus" issue, but I think I may be missing some steps in my diagnostics.

I have a 01 2500 CTD Auto 4x4 QCSB that had a transmission fail. The truck was running fine, and we decided to swap in a good donor trans from the exact same truck with 70K miles and no rust. Since the transmission was installed, I am getting the "no bus" code on the dash, and the typical crank-no-start, no dash gauges, lights on, etc.

In research, I did the following to diagnose:
- Check, clean, and grease connections C1, C2, and C3 at the PCM and the main connector on the PDC
- Check for codes, my code reader will not connect
- Look for broken wires, things that may not be plugged in, chewed wires, etc. - all good
- Measure resistance at pin 31 of the C1 connector, resistance was too high - repaired wire and ohm reading is now within spec
- Individually unplug all connectors C1-C3
- Unplug new trans
- Disconnect and reconnect battery after all of this, even replaced battery as the old one was dead

And I am still getting the code. Is there anything else I can check before just grabbing another computer? I find it hard to believe the computer died as it ran before the trans was in. Any help is appreciated!

TIA

 

Did you pinch some wires between the engine and trans?

 

I did not do the transmission install, it was handed off to my cousin that has access to a dealership shop. I did, though, get under and look with a flashlight and a mirror and did not see any pinched wires

 

The no bus error is a major pain to troubleshoot, too many possible causes..... Might try unplugging sensor, one at a time, and see which one (if any...) make the problem go away.

 

check all of your grounds