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

SUBJECT:

SIL 4-EP-13, Rev. B
February, 2019
Page 1 of 5

Increased Accessory Power 1 and 2 (IAP1) (IAP2)

MODELS AFFECTED:

All H 40/50 EP Drive Units

Introduction:
Introduced at the beginning of model year 2013, Increased Accessory Power 1 (IAP1) was the first system used
on the H 40/50 EPTM utilizing Vanner, Inc. components. This system provides up to 30KW of unconditioned DC
power to support equipment listed below:
• Vanner High Voltage Distribution Module (HVDM)
• Vanner Hybrid Beltless Alternator (HBA) - DC to DC converter for high-voltage to low-voltage
• Heating, ventilation, and air conditioning equipment
Increased Accessory Power 2 (IAP2) was introduced in the last quarter of 2014. The IAP2 system allows for the
use of the Vanner Exportable Power Inverter (VEPI) which can output up to 300 amps of three-phase 230V AC
power. Like the IAP1 system, IAP2 continues to provide up to 30KW of DC power and continues to support up to
two (2) Vanner HBAs and unconditioned high-voltage DC for other optional equipment.
Refer to Figure 1 for an overview of the IAP1 layout. Refer to Figure 2 for an overview of the IAP2 layout.
Allison Transmission supports Vanner IAP1 and IAP2 by offering SIDs designed for each system. SIDs for model
year 2013 began with “69” (69XXXXXYYYZ) and are used with IAP1. New SIDs released for model year 2014
began with 6B and allowed operation of the IAP2 with a VEPI.
CAUTION: If a High Voltage Distribution Module (HVDM) will be used with the H 40/50 EPTM, it MUST be
specified in the System Calibration System Identification Number (SID) when the SID is defined. April
2013 or later software is required; otherwise, the H 40/50 EPTM Controls will not be able to properly
maintain the Energy Storage System (ESS) State of Charge (SOC) in all operating conditions.

NOTE: Allison Transmission, Inc. is providing the capability of the H 40/50 EPTM to supply power to the
IAP1 and IAP2 systems from the ESS.

ML / SL7334EN

4460195

Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.

SIL 4-EP-13, Rev. B
February, 2019
Page 2 of 5

NOTE: The vehicle OEM high-voltage wiring must be specifically designed for IAP1 or IAP2 system
installation.
The high-voltage cable between the Energy Storage System (ESS) and the Dual Power Inverter Module (DPIM) will
include a splice to route power to the HVDM (refer to Figure 3). The HVDM and HVDM load channel components
include a High Voltage Interlock Loop (HVIL) switch activated (closed) by the their main covers. The low-voltage
wiring to these HVIL switches is added in series with the existing B Motor HVIL circuit between the DPIM and
the Drive Unit (refer to Figure 4).
NOTE: IAP1 and IAP2 systems can be configured with different components depending on what output is
needed for the vehicle.

Serviceability:
Prior to working on any high-voltage equipment, the Electrical Disconnect Verification Procedure should be
performed. The Electrical Disconnect Verification Procedure is included in the Electrical Safety section in various
H 40/50 EPTM service publications and provides instruction to verify that high voltage has dissipated and the
system is safe to work on.
Allison Transmission, Inc. recommends Allison Certified Technicians use Vanner's Dashboard software to aid with
troubleshooting when working on vehicles equipped with IAP1 or IAP2 systems incorporating Vanner components.
Copies of Vanner publications also contain helpful troubleshooting information as well as isolation fault testing
procedures and specifications. Please contact Vanner, Inc. for troubleshooting assistance and verification of
proper component replacement or repairs.
NOTE: To expedite repairs, please contact Vanner, Inc. for troubleshooting and verification of proper
component replacement or repair. Vanner can assist with arranging warranty work with the vehicle OEM
if required. The vehicle OEM is responsible for all integrated IAP1/IAP2 components and high-voltage
wiring harness. High-voltage wiring harness installations or repairs performed by Allison Transmission
distributors and dealers are not covered by Allison Transmission warranty.
For further information about the installation requirements for IAP1 or IAP2 with H 40/50 EPTM, refer to
Technical Document 192 (TD192), which is located in Tech Data on the Allison Transmission Extranet;
www.allisontransmission.com/extranet/techdata.
The HVDM, HBA, and VEPI all have their own DTCs. Equipment suppliers or the vehicle OEM can provide tools for
troubleshooting those DTCs and for programming components when necessary.
Currently, Vanner, Inc. is the sole manufacturer of distribution modules, DC-DC converters, and EPIs integrated
with IAP1 or IAP2. For service related concerns or to access the latest product manuals, contact Vanner, Inc. at
www.vanner.com/contact-vanner/

Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.

SIL 4-EP-13, Rev. B
February, 2019
Page 3 of 5

Figure 1. H 40/50 EPTM Increased Accessory Power 1 (IAP1) Layout

Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.

SIL 4-EP-13, Rev. B
February, 2019
Page 4 of 5

Figure 2. H 40/50 EPTM Increased Accessory Power 2 (IAP2) Layout

Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.

SIL 4-EP-13, Rev. B
February, 2019
Page 5 of 5

Figure 3. Typical OEM High Voltage Harness

Figure 4. DPIM With Optional HVDM, HVAC and DC-DC Power Converter HVIL Low Voltage Wiring Circuits

Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.