Hello Everyone, thank you for reading my post.

I'm in Dire need of some help:
I spend two weeks with my truck down as I removed, rebuilt and Re-installed my transmission.

After finally putting in the last couple of bolts, I was heartrbroken to discover the no start condition and be greeted on the dash with "No Bus" flashing in the odometer.
dodge ram 2500 2001 with 5.9 liter gas

Upon research I found that No Bus is related to fault in the 5 volt signal from the ECM. I verified that I did indeed have 5 volt signal at the throttle body sensor.

Upon visual inspection, I found that both the park indicator pigtail and the Transmission signal connector had significant insulation exposure and several wires in contact with each other. I did my best to verify all these wires were still intact and then electrically separated all of the wires by adding electrical tap to each of the exposed wires.

I also disconnected and inspected all of the O2 sensors and looked for any mashed pins / causes for electrical short. All O2 sensors seemed OK.

I also verified that no wires were pinched by the bell housing on re-installation.

I also removed the crank sensor and inspected it for damage.

Here are my questions...
Does anyone know of a common fault to look for with getting "no bus" in relation to transmission install?
What are the testing approaches I can use at the connectors of the transmission to make sure the transmission is performing as expected?
How can I test my wiring from the ECM to the transmission sensor to make sure my pigtail is intact and communicating with the transmission properly?
Are there any other questions I should be asking about this?

I did find this diagram and was intending to use it as a guide in testing for the specified resistances: https://atracom.blob.core.windows.ne...dec/atb497.pdf

Thank you for your time and attention in this matter. I really need to get this back on the road and get back to work before I get fired!!

Update: checked voltages:

The connector for that guy is so impossible to find... Also the fact that i'm seeing 5. volts on the control bus at the connectors of the throttle body and the transmission makes me think that the wiring harness issue may have fried the ECM. Wires were definitely touching each other. I separated them all and then tested the line conditions on Key On Condition:

Here's what I'm getting at the Transmission wiring harness with it disconnected:

Pin 1 ground :: Transmission Relay Output
Pin 2. 5.1 volts :: 5 v supply
Pin 3 - :: sensor ground <-- I did not sense any ground in sensor ground with the key on or key off - I'll check the trans side to see if its grounded
Pin 4 GND :: gov press sense signal
Pin 5 GND :: Gov Pressure Solenoid Control
Pin 6 GND :: Shift Solenoid control
Pin 7 5Volts :: torque converter Solenoid Control
Pin 8 5Vvolts :: Temp Sense Signal

Does anyone know if these voltages are correct or how to tell if my ECM is working correctly?
As you see 5V is present but computer says No Bus

== several days into this... ==
Ok here's an update... a couple thigs I tried...
I put it all back together and tried bypassing the fuel system relay: the truck would turn over but not start. Still showing No Bus.

I replaced the PCM with the one from my dodge durango. It's a different part number.
The truck started but ran terribly and died. Still showing no bus.

This leads me to believe that the PCM is shot. I was getting no system activation for the fuel system, but then when I replaced the PCM with the one from the durango, Fuel system came online.

I'm planning to have the PCM repaired or replaced. Not sure if I should be concerned that the durango PCM was also still throwing No Bus.
Wondering if maybe its just not compatible or maybe I also fried the ECM?

​​​​​​​Any thoughts?

 

What are you driving?

Usually, if the crank sensor isn't removed prior to trans R&R, it is frequently a victim..... Try unplugging the crank sensor, and see if things wake up. The truck (assuming a truck) will NOT start without the crank sensor though, but, that test should tell if it is the problem.

 

I did indeed remove the crank sensor when I removed the transmission. I also removed it again for inspection and it all looks fine.
The connector for that guy is so impossible to find... Also the fact that i'm seeing 5. volts on the control bus at the connectors of the throttle body and the transmission makes me think that the wiring harness issue may have fried the ECM. Wires were definitely touching each other. I separated them all and then tested the line conditions on Key On Condition:

Here's what I'm getting at the Transmission wiring harness with it disconnected:

Pin 1 ground :: Transmission Relay Output
Pin 2. 5.1 volts :: 5 v supply
Pin 3 - :: sensor ground <-- I did not sense any ground in sensor ground with the key on or key off - I'll check the trans side to see if its grounded
Pin 4 GND :: gov press sense signal
Pin 5 GND :: Gov Pressure Solenoid Control
Pin 6 GND :: Shift Solenoid control
Pin 7 5Volts :: torque converter Solenoid Control
Pin 8 5Vvolts :: Temp Sense Signal

Does anyone know if these voltages are correct or how to tell if my ECM is working correctly?
As you see 5V is present but computer says No Bus

 

Need to know what vehicle you are working on.

 

dodge ram 2500 2001 with 5.9 liter gas

 

TCC solenoid should have 12 volts......

 

Ok here's an update... a couple thigs I tried...
I put it all back together and tried bypassing the fuel system relay: the truck would turn over but not start. Still showing No Bus.

I replaced the PCM with the one from my dodge durango. It's a different part number.
The truck started but ran terribly and died. Still showing no bus.

This leads me to belive that the PCM is shot. I was getting no system activation for the fuel system, but then when I replaced the PCM with the one from the durango, Fuel system came online.

I'm planning to have the PCM repaired or replaced. Not sure if I should be concerned that the durango PCM was also still throwing No Bus.
Wondering if maybe its just not compatible or maybe I also fried the ECM?

Any thoughts?

 

Did you already try unplugging the connector from the transmission ? Did you put the PCM back into the Durango and does it run ?

 

The durango hasn't run in 5 years... It got benched for no reverse.
Now i'm in the process of tearing that transmission apart to at least get something going asap!

Meanwhile i'm trying to find options to have an working PCM in less than a week for less than $300.

 

Your local parts store should be able to do that for you......