SIL 8­TC10­16
February, 2016
Page 1 of 3
SUBJECT:

TC10 HARDWARE MODIFICATION ­ A65 TCMs, Rear Covers, and Interchangeability

MODELS AFFECTED:

TC10 Product Family Transmissions

SERIAL NUMBERS AFFECTED:

8810001001 to 8810001870

Effective February 2016, Allison Transmission, Inc. is making some modifications for the TC10 model.
The purpose of this Service Information Letter (SIL) is to highlight the A65 Transmission Control Module (TCM)
and rear cover modifications which occurred in February, 2016 and how this hardware change can affect
the interchangeability of these components when repairing a transmission or when used in the building of
Allison ReTran® Transmissions. This SIL will also outline the appropriate service procedures to address any
interchangeability issues with the current and former components.
Table 1. Rear Cover, A65 TCM, and Associated Hardware Part Numbers
P/N for S/N 8810001001
to S/N 8810001869

Part Name

P/N Beginning with S/N
8810001870

Description of Change

A65 TCM

29550693

29555551

Removal of brackets,
bushings, and isolators.
Machined steps removed
from TCM housing.

TCM Mounting Bracket (Left)

29557908

N/A

No longer Required

TCM Mounting Bracket
(Right)

29557909

N/A

No longer Required

Isolator Mount

29554722

N/A

No longer Required

Mounting Grommet Bushing

29554723

N/A

No longer Required

M8 Thread Forming Bolt

N/A

29557407

Required for service of
29555551 with 29553926

Rear Cover

29553926

29557408

Relocation of TCM mounting
bolt holes

SA / SL7773EN

3056563

Copyright © 2016 Allison Transmission, Inc. All Rights Reserved.

SIL 8­TC10­16
February, 2016
Page 2 of 3

Interchangeability:
Table 2. Interchangeabilty
Part Name

Current P/N

Former P/N

Former P/N
Maintained For
Service

8810001001
­ 8810001869
Service With

Beginning With
S/N 8810001870
Service With

29555551

A65 TCM

29555551

29550693

No

29555551
29557908
29557909
29554722
29554723
29557407

TCM Mounting
Bracket (Left)

N/A

29557908

Yes

29557908

N/A

TCM Mounting
Bracket (Right)

N/A

29557909

Yes

29557909

N/A

Isolator Mount

N/A

29554722

Yes

29554722

N/A

Mounting
Grommet Bushing

N/A

29554723

Yes

29554723

N/A

M8 Thread
Forming Bolt

29557407

N/A

N/A

29557407

N/A

Rear Cover

29557408

29553926

No

29555551
29557408

29557408

Parts Modifications:
The brackets, isolator mounts, and mounting grommet bushings have been removed from the current A65
TCM P/N 29555551 design. Improvements have been made to the internal components of the TCM which no
longer require the use of the aforementioned components. The machined steps on the TCM housing have also
been removed from the current TCM design.
The TCM mounting bolt hole locations have changed on the current rear cover P/N 29557408. This change
requires that the current A65 TCM P/N 29555551 is to be used with the current rear cover P/N 29557408. Former
A65 TCM P/N 29550693 is NOT to be used with rear cover P/N 29557408 due to lack of bolt support when the
brackets are removed.

Service Procedure When Replacing Former A65 TCM:
A65 TCM Removal
1. Loosen the bolt in the 24­way OEM vehicle wiring harness connector.
2. Disconnect the OEM vehicle wiring harness from the 24­way TCM connector.
3. Loosen the bolt in the 40­way external wiring harness connector.
4. Disconnect the external wiring harness from the 40­way TCM connector.
5. Remove the four bolts securing the former A65 TCM P/N 29550693 to the former rear cover P/N 29553926.

Copyright © 2016 Allison Transmission, Inc. All Rights Reserved.

SIL 8­TC10­16
February, 2016
Page 3 of 3
6. Remove the former A65 TCM P/N 29550693 from the former rear cover P/N 29553926.
7. Loosen the four bolts securing the isolator brackets to the former A65 TCM P/N 29550693.
8. Remove the isolator brackets, isolator mounts, and mounting grommet bushings from the former A65
TCM P/N 29550693.
A65 TCM Installation
1. Using four M8X1.25 Taptite® bolts, secure the isolator brackets, mounting grommet bushings, and isolator
mounts to the current A65 TCM P/N 29555551. Tighten the four bolts to 31­39 N∙m (23­29 lb ft).
NOTE: Being that Taptite® bolts are thread forming, it is recommended that the bolts are snugged,
backed out, and then properly torqued.
2. Install the current A65 TCM P/N 29555551 with TCM hardware onto the former rear cover P/N 29553926.
3. Install the four bolts that secure the TCM to the rear cover. Tighten the bolts to 10­13 N∙m (7­10 lb ft).
4. Connect the external wiring harness to the 40­way TCM connector.
5. Tighten the bolt securing the 40­way external wiring harness connector to the TCM, to 2­3 N∙m (12­24 lb in).
6. Connect the OEM vehicle wiring harness to the 24­way TCM connector.
7. Tighten the bolt securing the 24­way OEM vehicle wiring harness connector to the TCM, to 2­3 N∙m (12­24
lb in).

Service Procedure When Replacing Current A65 TCM:
A65 TCM Removal:
1. Loosen the bolt in the 24­way OEM vehicle wiring harness connector.
2. Disconnect the OEM vehicle wiring harness from the 24­way TCM connector.
3. Loosen the bolt in the 40­way external wiring harness connector.
4. Disconnect the external wiring harness from the 40­way TCM connector.
5. Remove the four bolts securing the current A65 TCM P/N 29555551 to the current rear cover P/N 29557408.
6. Remove the current A65 TCM P/N 29555551 from the former rear cover P/N 29557408.
A65 TCM Installation:
1. Install the current A65 TCM P/N 29555551 onto the current rear cover P/N 29557408.
2. Install the four bolts that secure the TCM to the rear cover. Tighten the bolts to 10­13 N∙m (7­10 lb ft).
3. Connect the external wiring harness to the 40­way TCM connector.
4. Tighten the bolt securing the 40­way external wiring harness connector to the TCM, to 2­3 N∙m (12­24 lb in).
5. Connect the OEM vehicle wiring harness to the 24­way TCM connector.
6. Tighten the bolt securing the 24­way OEM vehicle wiring harness connector to the TCM, to 2­3 N∙m (12­24
lb in).

Copyright © 2016 Allison Transmission, Inc. All Rights Reserved.