Allison transmission

[Don and Kathy DuCharme]

Attempted to move the coach today, and when I turned on the ignition switch the check transmission light was flashing.  The engine started, but transmission pad was non-functional. Display shows two zeros filled with what appears to be an asterisk. Pushing the up and down arrows simultaneously gave a momentary oL, but display would not stay on long enough to get codes.  I hear a clicking which correlates with the flashing check transmission light, and which is eliminated if I unplug the relay which feeds the TCM among many other things. Transmission fluid level appears to be OK on dip stick.  Any thoughts will be greatly appreciated.
Don

[Keith Moffett Co-Admin]

Is that the 4000 series Allison?
My quick guide says the temp must be up fully to display codes.  Push up and down once for oil level.  Push both twice for codes.

Good luck

[David T. Richelderfer]

I believe the transmission must be up to at least 140F for the shift pad to report.  Our coach's transmission almost never gets that hot.  It stays 40F to 50F degrees above outside ambient temperature.

[Don and Kathy DuCharme]

Can anyone tell me where the transmission control module is located in my 07 Contessa with the Allison 3000MH tranny? Thanks.

[David T. Richelderfer]

In our coach there is a black box about 5" x 7" x 1.5" inside the access panel right below the transmission keypad.  Whether or not that is the "control module" you are looking for is not in my mental database.  I know there are two auto fuses in that black box because I had to replace one once.

[Bryan Beamon]

Don our 07 Contessa "control module" is located in the outside compartment below the drivers area and tucked in the very top of the compartment. Suggest checking the connections on the module.Also check your speed sensor connection located at the back of your transmission . Good luck Bryan

[Don and Kathy DuCharme]

Thanks for the responses.  Bryan you are correct, the TCM is located at the top of the outside electrical bay, I had looked at it but it was not marked as Allison and I had no idea what it would look like.  A long story short, I exhausted my capability to diagnose the problem and resorted to calling the W.W. Williams Co which fortunately is nearby.  I called at 8:30 this morning, and by 12:00 a service tech was in my driveway.  Equipped with the computer diagnosis and all the pertinent electrical diagrams, we quickly determined that when the ignition switch was turned on the voltage to the shifter key pad dropped to 7.5 volts which is insufficient to operate the pad.  Did not determine why the voltage dropped, but by connecting a good 12.5 volt line the problem appears to be solved.  Less than 2 hrs. of tech time, and no parts.  The W.W. Williams Co. has facilities in several states around the country, and if they all provide the type of service we received I can strongly recommend them. 

[Jeremy Parrett]

Check your ignition solenoid perhaps?

[Joel Ashley]

Jeremy may be correct.  The solenoid in the electric bay has internal components that burn, wear, and may have quit transferring adequate current.  And check in the bay for corrosion or looseness any relay and breaker connections that are tranny-related, that may be causing resistance to intended current flow.

Joel