SIL 5­EP­16
January, 2016
Page 1 of 16
SUBJECT:

Replacing the DC Busbar Assembly and DC Terminal Block Inside the Dual Power Inverter Module
2 (DPIM2)

MODELS AFFECTED:

H 40/50 EP SystemTM Equipped With DPIM2

Tools Required
• 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 5)
• Pick or Small Flat Blade Screwdriver
• Torx PlusTM T20 Bit
• Torx PlusTM T25 Bit
• 8mm Hex Socket
• 13mm Hex Socket
• Loctite® 242
• Loctite® 425
Parts Required
• P/N 29540714 – Cover Gasket
• P/N 29540614 – DPIM DC Access Lug Box Cover EMI Gasket
• Wire Ties (4 inch – Nylon 6/6 or approved equivalent)

Introduction:
This Service Information Letter (SIL) announces the availability of the DC (Direct Current) busbar, DC terminal
block, and related components and includes the procedure to replace the DC busbar and DC terminal block. The
availability of this part eliminates the need for a complete DPIM replacement under certain failure conditions.
NOTE: Replacement of the DC Busbar and DC Terminal block is not a warrantable repair by Allison
Transmission, Inc. if damaged has been caused by arcing. Contact Allison TAC at (800) 252­5283 prior to
initiating repairs on a DPIM that is under warranty.

BC / SL7634EN

2823160

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

SIL 5­EP­16
January, 2016
Page 2 of 16

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

NOTE: Perform the necessary visual inspection prior to ordering parts. The parts are NOT available as a
complete kit. All necessary components must be ordered individually.

NOTE: If the DC Lug Box has been damaged, refer to SIL 08­EP­14 for replacement parts and procedures.

Refer to Figure 1 for locations of the DC busbars, DC terminal block and related components. Refer to Table 1 for
list of Service Parts.

Figure 1. DPIM2 Busbar Locations
Table 1. Service Parts (refer to Figure 2)
Item Number

Part Name

Part Number

1

Busbar – DC

29546732

2

Screw – M4x16mm

29540624

3

DC Terminal Block

29540604

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

SIL 5­EP­16
January, 2016
Page 3 of 16

Figure 2. Service Parts

Diagnosis:
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.
The DC busbar assembly and DC terminal block may need to be replaced if the HV lug bolt has become loose and
components are damaged by electrical arcing. Refer to Figure 3.

Figure 3. Damage to Busbar and Terminal Block Caused by Electrical Arcing

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

SIL 5­EP­16
January, 2016
Page 4 of 16

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.

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: Allison Transmission, Inc. requires the removal of the DPIM from the vehicle prior to performing
internal repairs. Prior to removal of the DPIM, refer to the H 40/50 EP SystemTM System Troubleshooting
Manual (TS5812EN) and perform the Electrical Disconnect Verification Procedure.

NOTE: Internal DPIM repairs should NOT be performed if smoke and/or water damage are present.
Photograph the smoke and/or water damage and contact Allison TAC at (800) 252­5283.

NOTE: Complete the DPIM Check List prior to replacing the DC busbar assembly and DC terminal block
to ensure additional components have not been 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 EP SystemTM Troubleshooting Manual (TS5812EN).

Figure 4. DPIM2 (Main Cover and Lug Box Covers Removed)
Copyright © 2016 Allison Transmission, Inc. All Rights Reserved.

SIL 5­EP­16
January, 2016
Page 5 of 16

The procedures contained in this SIL are organized into the following sections:
Section 1: Removal of Main Cover, HVIL Circuit Card, and DC Choke
Section 2: Replacement of the DC Busbar Assembly and DC Terminal Block
Section 3: Installation of DC Choke, HVIL Circuit Card and Main Cover

Section 1: Removal of Main Cover, HVIL Circuit Card, and DC Choke
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 5.

Figure 5. Electrostatic Discharge Wrist Strap (Tool Number 7744 Shown)
1. Using a Torx PlusTM T25 bit, remove twenty­six (26) M5x18mm machine screws that secure the Main
Cover to the DPIM Housing (refer to Figure 6). Set the screws aside for reassembly. Remove the Main
Cover. Discard the cover gasket.

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

SIL 5­EP­16
January, 2016
Page 6 of 16

Figure 6. DPIM Main Cover
2. Exercising care, cut one (1) wire tie at location shown in Figure 7. Do NOT remove any wire ties that pass
through the HVIL Circuit Card. Leaving the severed wire ties in place will provide a visual aid for wire tie
locations during installation of the replacement circuit card.

Figure 7. HVIL Circuit Card – Wire Tie Location

3. Cut the two (2) wire ties at locations shown in Figure 8 and remove them from the mounts. The wire
tie mounts do NOT have to be removed from the DPIM Housing unless they interfere with the removal
or installation of the HVIL circuit card.

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

SIL 5­EP­16
January, 2016
Page 7 of 16

Figure 8. HVIL Circuit Card – Two (2) Wire Tie Locations

CAUTION: Do NOT pull on the wires when removing connectors, doing so may pull the pins out of the
connector.

4. When removing connectors, push down on the tab at Location 1 and push the harness out of the connector
at Location 2 with a Pick or Small Flat Blade Screwdriver (refer to Figure 9).

Figure 9. HVIL Circuit Card Connector Removal

5. Remove three (3) wire harness connectors from HVIL Circuit Card surface mount connectors by gently
depressing the retaining tab with a pick or small flat blade screwdriver. Refer to Figure 10.
NOTE: Use care to avoid bending or damaging the circuit card connectors.

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

SIL 5­EP­16
January, 2016
Page 8 of 16

Figure 10. HVIL Circuit Card – Three (3) Harness Connector Locations
WARNING: Any conductive material (i.e. screws, bolts, nuts, etc.) can cause a short inside the DPIM that
will result in permanent and irreversible DPIM damage. All hardware must be accounted for throughout
the service procedure.

6. Using an 8mm hex socket, remove the four (4) M5 nut/washer assemblies as shown in Figure 11. Disconnect
the two (2) wire ring terminals from the studs.

Figure 11. HVIL Circuit Card – Four (4) Mounting Nut/Washer Locations (M5)

7. Using a Torx PlusTM T25 bit, remove the four (4) M5x30mm screws securing the HVIL Circuit Card as
shown in Figure 12.

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

SIL 5­EP­16
January, 2016
Page 9 of 16

Figure 12. HVIL Circuit Card – Four (4) Mounting Screw Locations (M5x30mm)

8. Using a Torx PlusTM T25 bit, remove the two (2) M5x14mm screws securing the HVIL Circuit Card as
shown in Figure 13.

Figure 13. HVIL Circuit Card – Two (2) Mounting Screw Locations (M5x14mm)

9. Using a Torx PlusTM T25 bit, remove the four (4) M5x22mm screws securing the HVIL Circuit Card as
shown in Figure 14.

Figure 14. HVIL Circuit Card – Four (4) Mounting Screw Locations (M5x22mm)
10. Lift the HVIL Circuit Card straight up and remove it from the DPIM Housing.
11. Remove the DC Choke (refer to Figure 15).

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

SIL 5­EP­16
January, 2016
Page 10 of 16

(1)

–

Choke

Figure 15. DC Choke Location

Section 2: Replacement of the DC Busbar Assembly and DC Terminal Block

1. Using a 13mm socket, remove the nut and washer that secure the HVIL switch to the DC lug box housing.
Unplug the two (2) wiring terminals from the ends of the HVIL switch. Remove the wire tie. Remove the
HVIL switch (refer to Figure 16). Make note of the wiring terminal and wire tie orientation for reinstallation.

(1)

–

HVIL Switch Nut

(2)

–

Wiring

(3)

–

Figure 16. DC Lug Box Components

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

Wire Tie

SIL 5­EP­16
January, 2016
Page 11 of 16

2. Remove and discard the DC busbar through the main cover opening (refer to Figure 17).

(1)

–

DC Busbar

Figure 17. DC Busbar Location

3. Using a Torx PlusTM T20 bit, remove the six (6) M4x16mm screws that secure the DC terminal block to the
DC lug box (refer to Figure 18). Remove and discard the DC terminal block from the DC lug box.

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

SIL 5­EP­16
January, 2016
Page 12 of 16

(1)

–

DC Terminal Block

Figure 18. DC Terminal Block and Fastener Locations

4. Place the DC terminal block into the DC lug box. Apply one drop of Loctite® 425 (or equivalent) to the
external threads of the six (6) M4x16mm screws. Using a Torx PlusTM T20 bit, install the six (6) M4x16mm
screws that secure the DC terminal block to the DC lug box (refer to Figure 18) and torque to 1.24­1.47
N∙m (10.97­13.01 lb in).
5. Insert the new DC busbar into the DC Lug Box through the main cover opening (refer to Figure 18).
6. Place the HVIL switch in the DC lug box. Connect the two (2) wiring terminals to the ends of the HVIL switch
(refer to Figure 19). Apply one drop of Loctite® 425 (or equivalent) to the external threads. Using a 13mm
socket, install the nut and washer that secure the HVIL switch to the DC lug box. Torque the nut to 1.9­2.2
N∙m (16.8­19.5 lb in). Install wire tie to secure the black wire to the HVIL switch and cut to length.

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

SIL 5­EP­16
January, 2016
Page 13 of 16

(1)
(2)

–
–

Black Terminal
HVIL Switch Nut and Washer

(3)
(4)

–
–

White Terminal
Wire Tie

Figure 19. DC Lug Box Components

Section 3: Installation of DC Choke, HVIL Circuit Card and Main Cover
1. Install the DC Choke, ensuring that the arrow is pointing towards the DC lug box (refer to Figure 20).

Figure 20. DC Choke Location

2. Insert one (1) new wire tie into the new HVIL Circuit Card at the same location as shown in Figure 21.

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

SIL 5­EP­16
January, 2016
Page 14 of 16

NOTE: To ease assembly, the new wire tie must be inserted through the hole in the circuit card prior to
installation in the DPIM Housing.

Figure 21. HVIL Circuit Card – Wire Tie Location

3. Install HVIL Circuit Card into the DPIM Housing.
NOTE: Ensure that the wire harnesses and individual wires are NOT pinched under the circuit card
during installation.
4. Connect the three (3) wiring harness connectors at locations shown in Figure 22.

Figure 22. HVIL Circuit Card – Three (3) Harness Connector Locations

5. Using a Torx Plus™ T25 bit, install and finger tighten the ten (10) M5 screws that secure the HVIL Circuit
Card to the DPIM Housing. Torque all M5 screws to 3.1­3.5 N∙m (27­31 lb in). Refer to Figure 23 for
fastener sizes and locations.

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

SIL 5­EP­16
January, 2016
Page 15 of 16

Figure 23. HVIL Circuit Card – Fastener Sizes/Locations

6. Install the two (2) wire ring terminals onto the studs at locations shown in Figure 24. Using an 8mm socket,
install four (4) M5 nut/washer assemblies onto the studs as shown in the same figure. Torque the nuts
to 3.1­3.5 N∙m (27­31 lb in).

Figure 24. HVIL Circuit Card – Four (4) Mounting Nut/Washer Locations (M5)

7. Secure wiring with new wire ties and clip excess length as required. Refer to Figure 21 and Figure 25 for
wire tie locations.

Figure 25. HVIL Circuit Card – Two (2) Wire Tie Locations

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

SIL 5­EP­16
January, 2016
Page 16 of 16

8. Install new Cover Gasket P/N 29540714. Using a Torx Plus™ T25 bit, install and finger tighten the twenty­six
(26) M5x18mm machine screws that secure the Main Cover to the DPIM Housing as shown in Figure 26.
Torque the screws to 3.1­3.5 N∙m (27­31 lb in).

Figure 26. DPIM Main Cover
NOTE: For additional information refer to H 40/50 EP SystemTM Service Manual SM3602EN Appendix E.

9. Complete the DPIM check sheet again to verify the repair before installing the DPIM on the bus.

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

DC
Terminal
Block

DC Lug
Box

AC Lug Box
Inverter B

AC Lug Box
Inverter A

AC Terminal
Block (x2)

AC Busbar (x6)

Diode
Inverter B

Diode
Inverter A

DC Busbar

Level 3

Current
Sensor (x6)

Level 1

BCA Card
Inverter B

BCA Card
Inverter A

X-Capacitor
(x18)

HVIL
Circuit
Board

HVIL
Switch

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.

HVIL
Switches

Copyright 2014 Allison Transmission, Inc. All Rights Reserved.

Levels of Assembly

DPIM2

C

A

B

B

Level 2

Gate Drive
Cards
Inverter B

Phase

Phase

Gate Drive
Cards
Inverter A

Level 4

DC Capacitor SKiM Module/IGBT
(x9)
Cards Inverter B

SKiM Module/IGBT
Cards Inverter A

Encoder
Motor B

Phase

Phase

HVIL Support

Discharge
Resistor

DC Choke

Encoder
Motor A

A

C

AC Bus Bar
Inverter B

Phase

Phase

AC Bus Bar
Inverter A

GN7499EN
201405

Signal
Interface