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 Allison Transmission Not shifting on Thomas Bus
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issamxd
New Member

3 Posts

Posted - 05/24/2017 :  02:45:56 AM  Show Profile  Visit issamxd's Homepage  Reply with Quote
Hello,


We have a Thomas Bus year 2003. With Cummins Engine = Cummins ISB Serial # 46253187
The transmission is Allison AD2000.
It was on a trip and the battery died. They jump started it with 24volts instead of 12volts. The transmission since then is stuck on 3rd (or it seems to be 3rd gear).
We are in Mauritania (Africa). Any help on this would be appreciated.
I am really not comfortable letting someone fool around with the transmission here.
Thank you

RonF
Top Member

867 Posts

Posted - 05/24/2017 :  04:32:51 AM  Show Profile  Reply with Quote
Check your fuses and relays. With 24 volts you may have blown a few.

US Army retired CMBT
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Fastback
Top Member

1500 Posts

Posted - 05/24/2017 :  04:35:21 AM  Show Profile  Reply with Quote
Might also try disconnecting batteries for a short time then reconnecting.

Why yes, the ORIGinal CHARGER is a Fastback
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issamxd
New Member

3 Posts

Posted - 05/24/2017 :  05:25:12 AM  Show Profile  Visit issamxd's Homepage  Reply with Quote
Many electrical issues like headlights not responding etc have happened but all changed and fixed.
The only thing remaining is the shifting problem.
we have disconnected the batteries for weeks and on again same thing.
You don"t think the 24volts could have affected the body valve on fried the wire harness to the transmission?
Thank you both for your replies.
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RonF
Top Member

867 Posts

Posted - 05/24/2017 :  05:29:51 AM  Show Profile  Reply with Quote
It my have fried the TCM, transmission control module.

US Army retired CMBT
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issamxd
New Member

3 Posts

Posted - 05/24/2017 :  07:17:29 AM  Show Profile  Visit issamxd's Homepage  Reply with Quote
Is the TCM located inside the transmission or outside?
Any idea where we need to check?
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slippert
Top Member

USA
630 Posts

Posted - 05/25/2017 :  05:21:54 AM  Show Profile  Click to see slippert's MSN Messenger address  Reply with Quote
The TCM should be on the frame rail close to transmission and front axle, if it is same as in U.S.A.... I would be sure to check the fuse feeding power to TCM is good (^^as stated in post above^^)if acts like it is stuck in 3rd gear,sounds like tranny is is limpin mode,which if memory serves me gives you 3rd and reverse, which allows you the ability to drive it off the roadway and most times get it to a service facility ....can be caused by certain codes and or or loss of power to TCM...
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tigger2
Advanced Member

USA
469 Posts

Posted - 05/31/2017 :  1:33:34 PM  Show Profile  Click to see tigger2's MSN Messenger address  Reply with Quote
Next to the transmission control module there should be a smaller box with a hinged lid inside are relays and fuses to control the neutral safety interlock, cruise control signal, and power for transmission. The internal components are not very robust and can easily be damaged by corrosion and voltage spikes.
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