SIL 22­EP­16
April, 2016
Page 1 of 58
SUBJECT:

Replacing Current Sensors Inside 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
• 6mm Hex Key
• 8mm Hex Socket
• 11mm Hex Socket
• Loctite® 242
• Loctite® 425
• NyoGel® 760G Synthetic Lubricant
Parts Required
• Current Sensor and Harness Service Kit P/N 29557646 and/or P/N 29557647 (refer to following notes)

Introduction:
This Service Information Letter (SIL) announces the availability of the Current Sensor and Harness Service Kit
electronic service kit P/N 29557646 and electronic service kit P/N 29557647 and includes the procedure to replace
the Current Sensors located inside the DPIM2. The availability of these kits eliminates the need for a complete
DPIM replacement under certain failure conditions.
Electronic Service Kits P/N 29557646 and P/N 29557647 replace Electronic Service Kit P/N 29556287. These two
new kits (P/N 29557646 and P/N 29557647) allow for the current sensors to be mounted to the DPIM2 housing while

ML / SL7822EN

3172482

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SIL 22­EP­16
April, 2016
Page 2 of 58
the old kits (P/N 29556287) mounted the current sensors on the AC busbars. This Service Information Letter (SIL)
22­EP­16 is to be referenced when installing Electronic Service Kits P/N 29557646 and P/N 29557647 in a DPIM2.
NOTE: It is still acceptable to use Electronic Service Kit P/N 29556287 to repair a DPIM2 until stock of
P/N 29556287 is depleted. Reference the latest version of Service Information Letter (SIL) 12­EP­14
when installing Electronic Service Kit P/N 29556287 in a DPIM2.

NOTE: P/N 29557646 is required for inverter A side repairs. P/N 29557647 is required for inverter B
side repairs.

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

NOTE: Using one kit (P/N 29557646) will provide the parts necessary to replace Current Sensors on
Inverter A. Using one kit (P/N 29557647) will provide the parts necessary to replace Current Sensors on
Inverter B side. When replacing a failed Current Sensor, these kits will include components to replace
current sensors and harnesses on only ONE side of the DPIM (Inverter A or B).

NOTE: Two kits (P/N 29557646 and P/N 29557647) are required in order to replace all six (6) Current
Sensors in the DPIM.
Refer to Table 1 and Table 2 for Current Sensor and Harness Service Kit contents.
Table 1. Current Sensor and Harness Service Kit ­ Inverter A
Part Name

Part Number

Quantity

Electronic Service Kit

29557646

1

Harness Assembly

29547593

3

Inverter A Current Sensor

29547591

3

Gasket, Cover

29540714

1

Screw, M4 x 16

29557587

6

Tool, Alignment

29558018

1

Zip Tie – 4”

*

10

Zip Tie – 8”

*

5

* Zip Tie material to be nylon 6/6 or approved equivalent.

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SIL 22­EP­16
April, 2016
Page 3 of 58
Table 2. Current Sensor and Harness Service Kit ­ Inverter B
Part Name

Part Number

Quantity

Electronic Service Kit

29557647

1

Harness Assembly

29547593

3

Inverter B Current Sensor

29547482

3

Gasket, Cover

29540714

1

Screw, M4 x 16

29557587

6

Tool, Alignment

29558018

1

Zip Tie – 4”

*

10

Zip Tie – 8”

*

5

* Zip Tie material to be nylon 6/6 or approved equivalent.

NOTE: Perform the necessary diagnosis prior to ordering Current Sensor and Harness Service Kit,
P/N 29557646 or P/N 29557646. Contact Allison TAC at (800) 252­5283 to confirm the Current Sensor
failure.

NOTE: The DC lug box cover, lug box cover screws, and lug bolts are available as service parts. Refer to
the Parts Catalog PC3717EN for part number information.

NOTE: The DPIM Main Cover EMI Gasket (P/N 29540714 ­ Qty. 1, included in kit P/N 29557646 and
P/N 29557647), 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.

Warranty Claim Information:
1. When a Current Sensor and Harness Service Kit, P/N 29557646 or P/N 29557647, is utilized to repair a
failed DPIM under warranty, use Current Sensor and Harness Service Kit P/N 29557646 or P/N 29557647 as
the PFP and claim the kit part number in the Service Parts subsection of the AWAARE claim.
2. The replacement of Current Sensors on a DPIM2 under Allison supplied warranty must be approved by
Allison H 40/50 EPTM Service Engineering prior to removing DPIM Main Cover.

Diagnosis:
1. Check if ANY of the following Diagnostic Trouble Codes (DTCs) have been logged:
• DTC 73­23
• DTC 74­23
• DTC 73­24
• DTC 74­24
• DTC 73­25
• DTC 74­25

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SIL 22­EP­16
April, 2016
Page 4 of 58
• DTC 73­26
• DTC 74­26
• DTC 73­34
• DTC 74­34
• DTC 73­51
• DTC 74­51
NOTE: The DTCs listed above will identify which current sensor has failed.

2. Record any DTCs that are logged.
3. If any of the DTCs listed in Step 1 are logged, troubleshoot them per H 40/50 EPTM System Troubleshooting
Manual TS5812EN. In addition to troubleshooting the aforementioned DTCs, a DPIM Check List should be
completed. (Refer to the DPIM Check List appendix of the troubleshooting manual.) A failed Current Sensor
will not cause any of the DPIM Check List measurements to be out of specification. If any one of these
measurements are out of specification, additional DPIM components may need to be replaced.
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 Current
Sensor replacement. Prior to removal of the DPIM, refer to the H 40/50 EPTM System System
Troubleshooting Manual (TS5812EN) and perform the Electrical Disconnect Verification Procedure.

NOTE: The Current Sensor and Harness replacement 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: 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).

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SIL 22­EP­16
April, 2016
Page 5 of 58

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.

Figure 1. DPIM2 (Main Cover and Lug Box Covers Removed)

The procedures contained in this SIL are organized into the following sections:
Section 1: Removal of Main Cover and HVIL Circuit Card
Section 2: Removal of BCA Card Mounting Shelf
Section 3: Removal of the AC Busbar Assembly
Section 4: Removal/Installation of Current Sensor (Inverter A Phase C and Inverter B Phase A)
Section 5: Removal/Installation of Current Sensor (Inverter A Phases A and B, and Inverter B Phases B
and C)
Section 7: Installation of the AC Busbar Assembly
Section 8: Installation of BCA Card Mounting Shelf
Section 9: Installation of HVIL Circuit Card and Main Cover

Section 1: Removal of Main Cover and HVIL Circuit Card
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.

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SIL 22­EP­16
April, 2016
Page 6 of 58

Figure 2. 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 3). Set the screws aside for reassembly. Remove the Main
Cover. Discard the cover gasket.

Figure 3. DPIM Main Cover
2. Exercising care, cut one (1) zip tie at location shown in Figure 4. Do NOT remove any zip ties that pass
through the HVIL Circuit Card. Leaving the severed zip ties in place will provide a visual aid for zip tie
locations during installation of the replacement circuit card.

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SIL 22­EP­16
April, 2016
Page 7 of 58

Figure 4. HVIL Circuit Card – Zip Tie Location

3. Cut the two (2) zip ties at locations shown in Figure 5 and remove them from the mounts. The zip 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.

Figure 5. HVIL Circuit Card – Two (2) Zip 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 6).

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SIL 22­EP­16
April, 2016
Page 8 of 58

Figure 6. 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 7.
NOTE: Use care to avoid bending or damaging the circuit card connectors.

Figure 7. 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 socket, remove the four (4) M5 nut/washer assemblies as shown in Figure 8. Disconnect the
two (2) wire ring terminals from the studs.

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SIL 22­EP­16
April, 2016
Page 9 of 58

Figure 8. 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 9.

Figure 9. 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 10.

Figure 10. HVIL Circuit Card – Two (2) Mounting Screw Locations (M5x14mm)

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SIL 22­EP­16
April, 2016
Page 10 of 58
9. Using a Torx PlusTM T25 bit, remove the four (4) M5x22mm screws securing the HVIL Circuit Card as
shown in Figure 11.

Figure 11. 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. Verify that the choke is in place as shown in Figure 12.
NOTE: The choke may have adhered to the underside of the HVIL Circuit Card when it was removed. If
this has occurred, reinstall choke to its proper location as shown in Figure 12. The choke must be installed
with the arrow pointing toward the DC lug box.

(1)

–

Choke

Figure 12. Verification of Choke Installation

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SIL 22­EP­16
April, 2016
Page 11 of 58

Section 2: Removal of BCA Card Mounting Shelf
1. As required, carefully cut and remove the zip ties retaining the wire harnesses (refer to Figure 13).

Figure 13. zip tie Locations

2. Remove five (5) wire harness connectors from circuit card surface mount connectors by gently depressing
the retaining tab with a pick or small flat blade screwdriver (refer to Figure 14 and Figure 15).
NOTE: Use care to avoid bending or damaging the circuit card connectors.

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SIL 22­EP­16
April, 2016
Page 12 of 58

Figure 14. Wire Harness Connector Removal (4 Locations)

Figure 15. Wire Harness Connector Removal

3. Using a Torx PlusTM T25 bit, remove the seven (7) M5x14mm screws securing the BCA Mounting Shelf
(refer to Figure 16).

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SIL 22­EP­16
April, 2016
Page 13 of 58

NOTE: The BCA mounting shelf screws may twist off in the BCA standoffs during removal. Replacement
screws (P/N 29540535) and BCA standoffs (P/N 29548554) may be needed.

NOTE: If BCA standoffs unthread from the chassis while removing screws, unthread each standoff/screw
an equal amount to avoid stressing the BCA circuit card.

Figure 16. BCA Mounting Shelf Fastener Locations

4. Carefully lift the BCA Mounting Shelf and set in on the side of the chassis as shown in Figure 17.
NOTE: Three (3) harnesses are still connecting the BCA Card to the GATE Drive Cards. Do NOT relocate
the BCA Mounting Shelf any farther than as shown in Figure 17.

NOTE: If any BCA standoffs are still attached to the shelf do not let the BCA standoffs touch the GATE
drive circuit card.

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