Revisions to this document are noted
by a stripe in the left-hand margin

SUBJECT:

TT9108EN, Rev. A
January 09, 2024
Page 1 of 5

Diagnostic Trouble Code (DTC) U0404 in Freightliner and Western Star Vehicles

MODELS AFFECTED:

3000 and 4000 Series Transmissions with 6th Generation Controls

Description of Complaint:
Allison Transmission has identified concerns limited to Freightliner and Western Star vehicles using an Allison shift
selector with 6th Generation Controls, and C231 and C232 software levels:
• DTC U0404 may become active, indicating a communication issue between the TCM and shift selector
via the vehicle datalink.
• When active, the TCM illuminates the Check Trans light and disables pre-select capability.
This issue is covered under Daimler Truck North America (DTNA) Field Service Campaign SF680. This campaign
will terminate on November 30, 2024. Work completed after this date will not be reimbursed.

Cause:
Unexpected TC1 Transmission Requested Gear datalink messaging results in DTC U0404.

Tech Tip Transmission Identification:
Prior to the repair of a suspect transmission, verify that the Tech Tip repair has NOT already been performed.
Login to https://hub.allisontransmission.com/field-actions. Enter the transmission serial number and request
an authorization. If you receive an authorization number, this is confirmation that the Tech Tip has NOT been
performed. If the Tech Tip has NOT been performed, proceed with the repair. Include the authorization number in
the warranty claim narrative prior to submitting the claim. If you are unable to obtain an authorization number, and
you believe the transmission qualifies for the Field Action based on the serial number range, contact the Allison
Technical Assistance Center (TAC) at 1-800-252-5283 or 317-242-0700 or email: [email protected].

Allison Authorized Service Network Procedure:
Confirm that the vehicle is a Freightliner or Western Star and has an Allison shift selector with current software
level of C231 or C232. The software level can be identified by connecting Allison DOC® to the TCM (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. If the first four digits of the Cal ID are C231 or C232, then the
software level must be updated. Save a screenshot of the DTC and General Info tab showing the TCM serial
number and Cal ID prior to reprogramming the TCM.

ML / TT9108EN

6677097

Copyright © 2024 Allison Transmission, Inc. All Rights Reserved.

TT9108EN, Rev. A
January 09, 2024
Page 2 of 5

Figure 1. Current Software Level Example in Allison DOC

Copyright © 2024 Allison Transmission, Inc. All Rights Reserved.

TT9108EN, Rev. A
January 09, 2024
Page 3 of 5

Corrective Action Required:
If the vehicle is in the affected population, then update software level from C231 or C232 to C233 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 233 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 © 2024 Allison Transmission, Inc. All Rights Reserved.

TT9108EN, Rev. A
January 09, 2024
Page 4 of 5

Figure 3. Updated Software Level Example in Allison DOC

Copyright © 2024 Allison Transmission, Inc. All Rights Reserved.

TT9108EN, Rev. A
January 09, 2024
Page 5 of 5

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 and DTC(s) are present. Submission must be completed prior
to November 30, 2024.
Table 1. Claim Information
CLAIM TYPE

Campaign

FIELD ACTION

TT9108

PRIMARY FAILED PART

400

PRIMARY FAILED PART SERIAL NUMBER

TCM SN Recorded from Allison DOC

The field action authorization number must be provided in the “Work Performed Comments” field as shown
below in Figure 4.

Figure 4. Work Performed Comments
Table 2. Labor Codes/Hours – Recalibration Only
LABOR OPERATION CODE

LABOR HOURS

LABOR OPERATIONS

00096501

1.0

TCM Recalibration

00096400

0.5

Final Test Drive Vehicle

NOTE: No additional parts, labor or net items will be considered for this Tech Tip.

Copyright © 2024 Allison Transmission, Inc. All Rights Reserved.