Revisions to this document are noted
by a stripe in the left­hand margin

SUBJECT:

SIL 2­EP­16, Rev. A
April, 2016
Page 1 of 16

Replacing BCA (Bias­Control Assembly) Cards Inside of the Dual Power Inverter Module 2 (DPIM2)

MODELS AFFECTED:

H 40/50 EPTM System Equipped with DPIM2

Tools Required
• J­51586 Tab Bending Tool (available at Allison.service­solutions.com)
• J­46708 Multimeter (available at Allison.service­solutions.com) or equivalent
• Electrostatic Discharge Wrist Strap (Tool Number 7744 (available at Allison.service­solutions.com) or
equivalent) (Refer to Figure 2)
• Pick or Small Flat Blade Screwdriver
• Torx PlusTM T20 Bit
• Torx PlusTM T25 Bit
• 8mm Hex Socket
Parts Required
• Wire Ties (4 inch and 6 inch – Nylon 6/6 or approved equivalent)

Introduction:
This Service Information Letter (SIL) announces the availability of the BCA (Bias­Control Assembly) Card and
related components and includes the procedure to replace the BCA Card located inside the DPIM2. The availability
of this part eliminates the need for a complete DPIM2 replacement under certain failure conditions.
NOTE: Perform the necessary diagnosis prior to ordering parts related to a BCA Card failure. Contact
Allison TAC at (800) 252­5283 to confirm the BCA Card failure. The parts necessary to perform a BCA Card
replacement are NOT available as a kit. All necessary components MUST be ordered individually.
Refer to Figure 1 for location of BCA Card and related components. Refer to Table 1 for list of BCA Card Service
Parts.

BC / SL7631EN

3202116

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

SIL 2­EP­16, Rev. A
April, 2016
Page 2 of 16

Warranty Claim Information:
CAUTION: The Inverter A and Inverter B BCA cards are not interchangeable. Although the hardware
is identical, the base programming loaded into each card is unique to Inverter A or Inverter B. The
SID MUST be re­flashed when a BCA Card is replaced.

Figure 1. BCA Card and Related Components
Table 1. BCA Card Service Parts
Item Number

Part Name

Part Number

1

BCA – Inverter A

29557268

2

BCA – Inverter B

29557269

3

Screw – M4X14mm

29540721

1. When a BCA Card, P/N 29557268 or P/N 29557269, is utilized to repair a failed DPIM under warranty, use
P/N 29557268 or P/N 29557269 as the PFP and claim the same part number in the Service Parts subsection
of the AWAARE claim.
2. The replacement of BCA cards on a DPIM2 under Allison supplied warranty must be approved by Allison
H 40/50 EPTM Service Engineering prior to removing DPIM Main Cover.
NOTE: The DPIM Main Cover EMI Gasket (P/N 29540714 ­ Qty. 1, the DPIM DC Access Lug Box
Cover EMI Gasket (P/N 29540614 ­ Qty. 1), and the DPIM AC Access Lug Box Cover EMI Gaskets
(P/N 29540715 ­ Qty. 2 Required) should be discarded and replaced with new gaskets whenever the
covers are removed.

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

SIL 2­EP­16, Rev. A
April, 2016
Page 3 of 16

NOTE: Allison Transmission, Inc. requires the removal of the DPIM from the vehicle prior to BCA Card
replacement. Prior to removal of the DPIM, refer to the H 40/50 EPTM System Troubleshooting Manual
(TS5812EN) and perform the Electrical Disconnect Verification Procedure.

NOTE: The BCA Card replacement should NOT be performed if smoke and/or water damage are present.

WARNING: Smoke inside the DPIM contains harmful Copper Oxide. Use proper protective equipment to
protect your skin and eyes from contact. Avoid inhalation of smoke.

NOTE: Refer to the attachment at the end of this SIL for information regarding the name and location of
components within the DPIM2.

WARNING: DO NOT rely on the High Voltage Interlock Loop (HVIL) or control systems to de­energize
the system. Always perform the Electrical Disconnect Verification Procedure to be sure the system is
discharged before servicing components.
DO NOT attempt to bypass any High Voltage Interlock for any reason. Tampering with the HVIL may result
in injury. Failure to follow proper safety procedures may result in serious personal injury or death.

Removal of Main Cover
NOTE: The Main Cover MUST be removed prior to performing diagnosis of the DPIM.

NOTE: All circuit cards in the DPIM2 are sensitive to Electrostatic Discharge (ESD). ESD damage can be
caused by voltage levels that cannot be felt by humans. When working on the DPIM2, ALWAYS wear an
ESD wrist strap to ground any possible electrostatic charge. The strap should be worn around the wrist
with the alligator clip securely attached to the DPIM chassis. Refer to Figure 2.

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

SIL 2­EP­16, Rev. A
April, 2016
Page 4 of 16

Figure 2. Electrostatic Discharge Wrist Strap (Tool Number 7744 Shown)
Using a Torx PlusTM T25 bit, remove twenty­six (26) M5x18mm machine screws that secure the Main Cover to
the DPIM Housing (refer to Figure 3). Set the screws aside for reassembly. Remove the Main Cover. Discard
the cover gasket.

Figure 3. DPIM Main Cover

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

SIL 2­EP­16, Rev. A
April, 2016
Page 5 of 16

Diagnosis:
NOTE: Complete the DPIM Check Sheet prior to initiating DPIM repairs to help determine if additional
components are damaged. All cables (AC and DC) must be removed from the DPIM prior to taking
measurements shown on the DPIM Check List. For additional information, refer to H 40/50 EPTM System
Troubleshooting Manual (TS5812EN).

NOTE: For assistance regarding the troubleshooting of BCA Cards, contact Allison TAC at (800) 252­5283.

Scenario 1:
Condition: CAN Issues
DTC 66­31 (CAN Link Lost with Inverter A Long Timeout)
DTC 66­32 (CAN Link Lost with Inverter B Long Timeout)
1. If CAN link lost codes are active for both inverter A and B, then the issue is likely external to the DPIM or the
DPIM is not receiving the 12V wakeup.
2. If only one (1) inverter has CAN link codes, the BCA card on that inverter may need to be replaced.
Scenario 2:
Condition: Fuse (10­40A) for 12V DPIM power or fuse (10A) for 12V DPIM wakeup fails whenever the DPIM 24­way
connector is plugged in.
1. Check for smoke damage.
2. Inspect the BCA cards for damaged components (refer to Figure 4). Replace BCA card if damage is
discovered and verify the repair. If damage is NOT found, continue troubleshooting per the below steps
until the failed component is identified.

Figure 4. Damaged BCA Card

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

SIL 2­EP­16, Rev. A
April, 2016
Page 6 of 16

3. Isolate each of the low voltage circuits of each inverter by removing the two (2) white connectors from
the signal interface. Refer to Figure 5.

Figure 5. Signal Interface Connectors
a. Plug in the OEM 24­way connector with the two (2) internal harness connectors removed from the
Signal Interface. If the 10A fuse fails again, the Signal Interface may need to be replaced.
b. Plug the white A­Inverter connector into the Signal Interface and “Key On” the bus.
• If the 10A fuse fails again, the issue is with the A­Inverter.
• If the 10A fuse does NOT fail, connect the connector for the B­Inverter while leaving the white
A­inverter connector mated and “Key On” the bus to determine if the B­Inverter is causing
the 10A fuse failure.
4. After determining which inverter is causing the 10A fuse to fail, disconnect the three (3) ribbon cables going
to the Gate Drives (refer to Figure 6).

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

SIL 2­EP­16, Rev. A
April, 2016
Page 7 of 16

Figure 6. BCA Card Ribbon Cables

a. Use the handle of Tab Bending Tool P/N J­51586 to disengage and remove the three (3) cable strain
relief caps from the BCA card ribbon cable connectors (refer to Figure 7).

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

SIL 2­EP­16, Rev. A
April, 2016
Page 8 of 16

Figure 7. Removing Cable Strain Relief Caps

b. Press the tabs down on both sides of the BCA Card Connector to release the ribbon cable connector
(refer to Figure 8).

Figure 8. Releasing the BCA Card Ribbon Cable Connector
CAUTION: Do NOT pull on the wires when removing the ribbon cable connectors. Doing so may pull
the pins out of the connector.

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

SIL 2­EP­16, Rev. A
April, 2016
Page 9 of 16
5. “Key On” the bus. If the 10A fuse fails, replace the BCA Card.
6. If the 10A fuse for 12V DPIM wakeup did NOT fail with the three (3) BCA ribbon cables disconnected,
perform the following:
a. Reconnect only ONE ribbon cable connector and “Key On” the bus.
(1) If the 10A Fuse does NOT fail, “Key Off” the bus and go to Step 6b.
(2) If the 10A fuse fails, replace that phase SKiM Module and GATE Drive Card.
b. Repeat Step 6a for each of the remaining ribbon cable connectors.
NOTE: Refer to SIL 1­EP­15 (Replacing SKiM Module and GATE Drive Card Inside of the Dual Power
Inverter Module 2 (DPIM2)).

BCA Card Removal
1. Remove three (3) ribbon cable retainers from the BCA Card as follows (refer to Figure 9):

Figure 9. BCA Card Ribbon Cable Retainer Locations

a. Use the handle of Tab Bending Tool J­51586 to disengage and remove the three (3) cable strain relief
caps from the BCA Card ribbon cable connectors (refer to Figure 10).

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

SIL 2­EP­16, Rev. A
April, 2016
Page 10 of 16

Figure 10. Cable Strain Relief Cap Removal

b. Press the tabs down on both sides of the BCA Card Connector to release the ribbon cable connector
(refer to Figure 11).
CAUTION: Do NOT pull on the wires when removing the ribbon cable connectors. Doing so may pull
the pins out of the connector.

Figure 11. Releasing the BCA Card Cable Connector
Copyright © 2016 Allison Transmission, Inc. All Rights Reserved.

SIL 2­EP­16, Rev. A
April, 2016
Page 11 of 16

2. Label the three (3) current sensor harnesses to ensure they are connected to the correct location during
reassembly (refer to Figure 12).

Figure 12. Labeling the Three (3) Current Sensor Harness Locations

3. Remove five (5) wire harness connectors from the circuit card surface mount connectors by gently
depressing the retaining tab with a pick or small flat blade screw driver (refer to Figure 13).
NOTE: Use care to avoid bending or damaging the circuit card connectors.

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

SIL 2­EP­16, Rev. A
April, 2016
Page 12 of 16

Figure 13. Five (5) Wire Harness Connector Locations

4. Using a Torx PlusTM T20 bit, remove the eleven (11) M4x14mm screws securing the BCA Card to the
BCA Mounting Shelf (refer to Figure 14). The BCA Card should no longer be fastened to the BCA mounting
shelf.

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

SIL 2­EP­16, Rev. A
April, 2016
Page 13 of 16

Figure 14. BCA Card Mounting Screw Locations

5. Move the BCA Card to allow for easier removal of the one (1) remaining connector (refer to Figure 15).
Remove the defective BCA Card from the DPIM.

Figure 15. BCA Card Connector Location

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

SIL 2­EP­16, Rev. A
April, 2016
Page 14 of 16

Installation of New BCA Card and Main Cover
CAUTION: The Inverter A and Inverter B BCA cards are NOT interchangeable. Ensure that the correct
part number is used for the BCA Card being replaced. Although the hardware is identical, the base
programming previously loaded into each card is unique to Inverter A or Inverter B. The SID MUST be
re­flashed when a BCA Card is replaced.

NOTE: To allow ease of installation, do NOT mount the BCA Card to the BCA Shelf until after the wiring
harnesses are connected.
1. Connect the nine (9) wiring harnesses to the BCA Card (refer to Figure 16).

Figure 16. BCA Card Wiring Harness Locations

2. Install the three (3) ribbon cable retainers on the BCA card (refer to Figure 17).

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

SIL 2­EP­16, Rev. A
April, 2016
Page 15 of 16

Figure 17. BCA Card Ribbon Cable Retainer Locations

3. Using a Torx PlusTM T20 bit, install the eleven (11) M4x14mm screws securing the BCA Card to the
BCA Mounting Shelf (refer to Figure 18). Torque the eleven (11) M4x14mm screws to 1.2­1.5 N∙m (11­13
lb in).

Figure 18. BCA Card Mounting Screw Locations

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

SIL 2­EP­16, Rev. A
April, 2016
Page 16 of 16
4. Install new Cover Gasket P/N 29540714. Using a Torx PlusTM T25 bit, install and finger tighten the twenty­six
(26) M5x18mm machine screws that secure the Main Cover to the DPIM Housing (refer to Figure 19). Torque
the screws to 3.1­3.5 N∙m (27­31 lb in).

Figure 19. DPIM Main Cover
NOTE: For additional information refer to H 40/50 EPTM System Service Manual SM3602EN Appendix E.

5. Complete the DPIM check sheet again to verify the repair before installing the DPIM on the bus.
6. After installing the DPIM on the bus, re­flash the SID to calibrate the new BCA Card.

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

NOTE: This illustration is to be used for identifying the name and location
of components within the Dual Power Inverter Module 2 (DPIM2). It is not
intended to be used for disassembly and assembly procedures.

DPIM2
Levels of Assembly

DC Lug
Box

HVIL
Switch

BCA Card
Inverter A

Diode
Inverter A

AC Lug Box
Inverter A

Encoder
Motor A

DC Choke

Gate Drive
Cards
Inverter A

AC Bus Bar
Inverter A

Phase

A

Phase

B

Phase

C

Phase

C

Phase

B

Phase

A

Signal
Interface

HVIL
Switches

DC
Terminal
Block

HVIL
Circuit
Board

BCA Card
Inverter B

Diode
Inverter B

Discharge
Resistor

AC Lug Box
Inverter B

Encoder
Motor B

Level 1
Current
Sensor (x6)

X-Capacitor
(x18)

Level 3

AC Bus Bar
Inverter B

Level 2

AC Busbar (x6)

DC Busbar

Gate Drive
Cards
Inverter B

HVIL Support

AC Terminal
Block (x2)

SKiM Module/IGBT
Cards Inverter A

DC Capacitor SKiM Module/IGBT
(x9)
Cards Inverter B
Copyright 2014 Allison Transmission, Inc. All Rights Reserved.

Level 4

GN7499EN
201405