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March 08, 2023
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SUBJECT:

Diagnostic Trouble Code (DTC) U0103 in Prevost Vehicles

MODELS AFFECTED:

B 500 Bus SeriesTM and 4000 Motorhome SeriesTM Transmissions with 6th Generation
Controls

Description of Complaint:
Allison Transmission has identified concerns limited to Prevost vehicles with 6th Generation and C221, C222,
C223 and C224 software levels:
• DTC U0103 may become active, indicating a communication issue between the TCM and shift selector
via the vehicle datalink.
• When active, the engine will not crank.
• DTCs U0304 and U0404 may also be present.
The Prevost bulletin number associated with this issue is WB23-04.

Cause:
The current configuration of the ETC2 Transmission Requested Range signal prevents the engine from cranking
when a shift selector DTC is active and prevents self-clearing if the error is no longer present.

Allison Authorized Service Network Procedure:
If the engine will not crank, DTC U0103 can be cleared at the shift selector. Towing should be unnecessary.
Confirm that the current software level is C221, C222, C223 or C224. This can be identified by connecting to
the TCM with Allison DOC® (refer to Figure 1). The DTC and General Info tab will show the Cal ID in the TCM
Information section. The first four digits of the Cal ID provide the current software level. The software level must be
updated if the first four digits of the Cal ID are any of the following: C221, C222, C223 or C224. Save a screenshot
of the DTC and General Info tab showing the TCM serial number and Cal ID prior to reprogramming the TCM.

ML / TT9076EN

6452967

Copyright © 2023 Allison Transmission, Inc. All Rights Reserved.

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March 08, 2023
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Figure 1. Current Software Level Example in Allison DOC

Copyright © 2023 Allison Transmission, Inc. All Rights Reserved.

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Corrective Action Required:
If the vehicle is in the affected population, then update software level from C221, C222, C223 or C224 to C231 or
later by programming based on the TCM serial number in TCM ReflashTM. To receive the latest software level, it
is necessary to check the box labeled “Download Latest Calibration” on the Add screen in TCM Reflash (refer
to Figure 2). After programming is complete, use Allison DOC to verify that the second through fourth digits
of the Cal ID are 231 or greater (refer to Figure 3).

Figure 2. Updating to Latest Software Level in TCM Reflash
NOTE: The “Download Latest Calibration” option in TCM Reflash should only be used when there is a
specific need to update the software.

Copyright © 2023 Allison Transmission, Inc. All Rights Reserved.

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March 08, 2023
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Figure 3. Updated Software Level Example in Allison DOC

Copyright © 2023 Allison Transmission, Inc. All Rights Reserved.

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March 08, 2023
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Claim Submittal Information:
The Allison Authorized Service Network must submit work performed per this Tech Tip as outlined below and in
Table 1 and Table 2 if the appropriate conditions are present.
Table 1. Claim Information
CLAIM TYPE

Machine

PRIMARY FAILED PART

400

PRIMARY FAILED PART SERIAL NUMBER

TCM SN Recorded from Allison DOC

Attach the screenshot of the DTC and General Information screen in Allison DOC before reprogramming the TCM.
The TCM serial number and Cal ID must be shown in the screenshot. The first four digits of the Cal ID must
show as C221, C222, C223 or C224 (refer to Figure 1).
Table 2. Labor Codes/Hours – Recalibration Only
LABOR OPERATION CODE

LABOR HOURS

LABOR OPERATIONS

00096501

1.0

RECALIBRATE TCM

00096400

0.5

TEST DRIVE

00096901

0.5

TROUBLESHOOTING

Copyright © 2023 Allison Transmission, Inc. All Rights Reserved.