ECM location for 3000 series Allison transmission

[ktloah]

My 04 Dynasty is at DDA repair  for a speed sensor failure. Does anyone know where the ECM for the transmission is located? Any info would help...Thanks

[vito.a]

The Allison ECU and the HWH leveling computer are attached to the basement ceiling in the main basement compartment where the inverter is located.  You'll need to remove the black felt/plywood ceiling cover to access them.  

Make sure you check the wire connecter on the front of the Allison.  

[Frank McElroy]

It's likely in the ceiling between the frame rails in the first storage bin behind the front fuel tank.  You will need to unscrew this center ceiling cover to gain access

[ktloah]

Thanks Frank, when replacing the speed sensor I assume they need to program it to the ECM? DDA is wanting to know this. Thanks, I'll relay that this is possibly where it is

[Frank McElroy]

Likely they don't need access to the transmission ECM to replace the sensor.  Electronic access to the transmission computer should be via the rear databus port using the Allison software.  The transmission should be on the same databus diagnostic port as the engine.

The rear databus port is in the engine bay on the passenger side below the RRB (rear run bay electrical panel box).

[ktloah]

Thankyou for the info Frank...love this group!!