27-EP-15EN Rev B Service Bulletin/Repair Instructions

Revisions to this document are noted

by a stripe in the left-hand margin
SUBJECT:
SIL 27-EP-15, Rev. B

January, 2019

Page 1 of 15
Using Amprobe Ohm Megger (Model AMB-45) for Troubleshooting
MODELS AFFECTED:
H 40/50 EPTM System Transmissions
SERIAL NUMBERS AFFECTED:
ALL
Tools Required

• Amprobe Ohm Megger (Model AMB-45) is available on the Allison Parts and Service website

(Allison.service-solutions.com)
Introduction:

The purpose of this SIL is to explain how the Amprobe Ohm Megger (Model AMB-45) can be used to measure

the insulation resistance of various hybrid components which includes AC and DC cables, stator assemblies and

isolation faults in the Energy Storage System (ESS).

The Amprobe Ohm Megger is a digital tool that generates a high voltage signal of 250, 500 or 1000V.

It will show resistance to ground and provides a reading of 0 to 4000 megaohms.

NOTE: The Amprobe Ohm Megger (Model AMB-45) is a mandatory service tool that all authorized

H 40/50 EPTM distributors and dealers should already have to troubleshoot isolation concerns.
RL / SL7726EN
4358795
Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.
SIL 27-EP-15, Rev. B

January, 2019

Page 2 of 15
Figure 1. Amprobe Ohm Megger (AMB45) Insulation Resistance Meter with Built-in Voltmeter

to Test Insulation of Wires, Cables, Transformers, and Electrical Motors

Features of Amprobe Ohm Megger (Model AMB-45):

• Digital meter with automatic range selection

• Internal memory stores up to 4000 test results for future download to a PC

• Measures voltage from 0 to 600V AC or DC and insulation resistance from 0 to 4000 megaohms with

250, 500, and 1000V DC test voltage

• Safety rated to European Standard EN 61010-1 Category III 600V and Category II 1000V

• Built-in voltmeter

• Internal memory to store measurements for future reference
Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.
SIL 27-EP-15, Rev. B

January, 2019

Page 3 of 15
AC and DC High Voltage Cable Testing:

WARNING: The ESS contains hazardous electrical energy. To help avoid serious bodily injury including

death, electrocutions, and burns, follow approved electrical safety procedures. Refer to section 2 in

SM4162EN for electrical Disconnect Verification Procedure.
NOTE: For all tests the ESS should be disconnected.
The AC high voltage cables will need to be disconnected from the DPIM. Make sure the cables ends are not

touching.

There are three tests that can be performed to verify that isolation is good.

Test One: Cables Connected at Drive Unit

Connect the Megger red lead to phase A and the black lead to the chassis. Do this for motor A and B. If readings

are over >100 megaohms, this indicates good insulation resistance between the phase cable and chassis ground

(refer to Figure 2 ).

NOTE: The specification for ALL isolation fault testing is greater than >100 megaohms is good.
Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.
SIL 27-EP-15, Rev. B

January, 2019

Page 4 of 15
Figure 2. Test One
Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.
SIL 27-EP-15, Rev. B

January, 2019

Page 5 of 15

Test Two: Cables Disconnected at DPIM and Drive Unit

NOTE: This test requires the AC high voltage cables to be disconnected from both DPIM and the drive unit.
Cable lug end covers work well to protect the six AC cables ends from grounding to each other and to the drive unit

lug box case. A good quality electrical tape may be also be used to wrap the cable ends.

Connect the Megger red lead to phase A cable end, then connect the black lead to phase B cable end. Push the

yellow 1000 volt button. If the reading is over >100 megaohms, there is good insulation resistance between AC

phase A and B cables. Check between phase A and C and for phase B and C. Continue this test for B motor

(refer to Figure 3).

NOTE: The specification for ALL isolation fault testing is greater than >100 megaohms is good.
Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.
SIL 27-EP-15, Rev. B

January, 2019

Page 6 of 15
Figure 3. Test Two
Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.
SIL 27-EP-15, Rev. B

January, 2019

Page 7 of 15

Test Three: Motor Isolated

Connect the Megger red lead to phase A of motor A, then connect the black lead to the stator housing. Do the

same tests between motor B phase A and the stator housing. A reading greater than >100 megaohms indicates

good insulation resistance (refer to Figure 4).

NOTE: The specification for ALL isolation fault testing is greater than >100 megaohms is good.
Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.
SIL 27-EP-15, Rev. B

January, 2019

Page 8 of 15
Figure 4. Test Three
Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.
SIL 27-EP-15, Rev. B

January, 2019

Page 9 of 15
NOTE: The two DC cables can be tested using the same techniques as the six AC cables.

The specification for ALL isolation fault testing is greater than >100 megaohms is good.

Test Four: Cables Disconnected at DPIM and ESS

NOTE: You MUST disconnect any optional High Voltage accessory equipment from the DC cables such

as the DC to DC converter, High Voltage Distribution Module or other High Voltage DC Accessories

prior to performing this test.

Connect the Megger red lead to the DC+ cable and the black lead to the chassis. Push the yellow button with the

Megger set to the 1000 volt scale. If readings are over >100 megaohms, this indicates good insulation resistance

between the DC cable and chassis ground (refer to Figure 5). Do this for the DC+ and then the DC- cable.

NOTE: The specification for ALL isolation fault testing is greater than >100 megaohms is good.
Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.
SIL 27-EP-15, Rev. B

January, 2019

Page 10 of 15
Figure 5. Test Four
Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.
SIL 27-EP-15, Rev. B

January, 2019

Page 11 of 15

Test Five: Cables Disconnected at DPIM and ESS

NOTE: You MUST disconnect any optional High Voltage accessory equipment from the DC cables such

as the DC to DC converter, High Voltage Distribution Module or other High Voltage DC Accessories

prior to performing this test.

Connect the Megger red lead to the DC+ cable and the black lead to the DC- cable. Push the yellow button

with the Megger set to the 1000 volt scale. If readings are over >100 megaohms, this indicates good insulation

resistance between the DC cables. (refer to Figure 6 ).

NOTE: The specification for ALL isolation fault testing is greater than >100 megaohms is good.
Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.
SIL 27-EP-15, Rev. B

January, 2019

Page 12 of 15
Figure 6. Test Five
Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.
SIL 27-EP-15, Rev. B

January, 2019

Page 13 of 15
ESS Isolation Fault Testing:

DTC 77-27 Battery Substring High Voltage Isolation fault.

When this DTC sets, there is an isolation condition inside the ESS. The isolation condition will be active when there

is less than 0.780 megaohms between the ESS and chassis ground for more than 4 seconds.
Figure 7. Disconnect all Service Connectors.
Figure 8. Location of BCIM Power Plugs.

Remove all six orange plugs from BCIM’s while performing the Megger test on ESS.

To perform a Megger test on the ESS, connect the black lead to a chassis ground.

The red lead needs to be connected at each of the nine different check points listed on the ESS illustration

(refer to Figure 9)

These test points are referenced in list below for the (3) fuses (3) low relays and (3) high relays.

1. Attach red lead at each of the low side relays at the copper terminal labeled 1+

2. Attach red lead at each of the high side relays again at the terminal labeled 1+
Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.
SIL 27-EP-15, Rev. B

January, 2019

Page 14 of 15

3. Attach red lead at each of the three fuses.

NOTE: The specification for ALL isolation fault testing is greater than >100 megaohms is good.
Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.
SIL 27-EP-15, Rev. B

January, 2019

Page 15 of 15
Figure 9. PEVE Recommended Test.
Copyright © 2019 Allison Transmission, Inc. All Rights Reserved.

SaleBestseller No. 1

ANCEL X7HD 10'' Heavy Duty Truck Scanner, Semi Trucks Full System Diagnostic Tool, Bidirectional Diesel Scan Tool with DPF, ECU Coding, 40+ Reset for Cummins, Detroit, Caterpillar, Volvo, Paccar etc

🔥🔥🔥2026 New Functions Making X7HD the Top Dog - Big Surprise!!! ANCEL X7HD truck scanner 10 major functional advantages .✅>Full HDOBD/OBD2 Function ✅>ALL System Diagnostic ✅>42+ Reset Function ✅>Active Test / Bi-Directional Control✅>ECU Coding✅>Graphing Live Data✅>Wide Compatibility ✅>2 Yrs Free Update✅>Remote Operation✅>Bluetooth 5.0 & Wifi In addition, 8 major hardware advantages: ✅>6000 mAh✅>10.1 inch Tablet✅>2G RAM✅>32G ROM (Expandable to 128GB)✅>Data Record & Replay & Print✅>Android 10.0✅>Bluetooth 5.0 & Wifi✅>14 Languages
🚛OEM DPF Forced Regen & Cylinder Cutout Test & more - ANCEL X7HD diesel scanner diagnostic tool not only supports DPF regeneration, DPF reset, DPF related information reset, DPR state reset, DPD forced regeneration etc, which helps you better solve the exhaust aftertreatment system problems, but also supports activate motor to do exhaust air in ABS Automatically. Moreover, it features TPMS activation, cylinder cut-off and learning functions
🚛Advanced ECU Coding & Programming - ANCEL X7HD 10.1inch truck scanner diagnostic tool is equipped with advanced ECU coding, supports Level calibration, Idle speed learning and Adjustment, Camshaft timing control learning, Control unit adaptations, Injector Codes, Read/Write VIN, Road speed limit optional vehicle speed set, etc... PLEASE NOTE that ECU codes are not compatible with all vehicles, please send us your VIN# to check vehicle compatibility
🚛42+ Reset Functions & Bidirectional Control - 2026 newest top heavy duty truck scan tool, comes with 42+ special services (ECU, Speed Limit and Idle Reset, Oil Reset, Injector Coding, EPB, ABS, SRS, Suspension, Throttle, etc. and always keep growing), which meet all your various needs for service and maintenance
🚛10 Inch All Systems Diesel Scanner & Full HDOBD/OBD2 Modes - ANCEL X7HD diesel truck scan tool supports all systems scan, such as Engine, Brake, Retarder, TECU Transmission, Tachograph, ABS, SRS, TPMS, EPB, SAS, ESP, and other vehicle systems, comes with 10 obd2 service modes: read/erase error codes, Data Stream, I/M Readiness, Vehicle Information, Actuations, DTC Lookup, EVAP, view freeze frame, etc

SaleBestseller No. 2

ANCEL Heavy Duty Truck Scanner HD601 All System Diesel Diagnostic Scan Tool fits for Cummins, Detroit, Freightliner, International, Paccar, Check Engine for Truck & Car 2 in 1 Code Reader

【Extensive Compatibility】HD601 heavy duty truck scanner supports 12V & 24V commercial vehicles and all major truck models that comply with standard protocols (SAE J1939, SAE J1708, ISO 14230-4, ISO 15765-4 and ISO 9141-2, ISO 27145-4 and Euro6). Fits for Cummins, Paccar, Detroit, Caterpillar, Freightliner, International, Peterbilt, Ford Heavy Truck, Class 4-Class 8 trucks, etc. It also supports engine diagnosis on most cars, minivans, light trucks and pickups
【 Full System Diagnostic】HD601 Diesel Scanner supports all system scans of heavy trucks compliant with standard protocols SAE J1939 & J1708, such as Engine, ABS, Transmission, Braking System, ESP, EPS, Fuel System, etc, It is a great scan tool for Cummins, Caterpillar, Detroit, Caterpillar, Maxxforce, Bendix,Wabash, Wabaco, Haldex, Allison, Eaton heavy trucks, With this truck tool, you can get deep analysis data about the system and do some repairs by yourself, saving much time and money. Note: Only heavy truck vehicles that comply with the above protocol can diagnose the entire system
【Enhanced Diesel OBD Scanner】The HD601 Diesel OBD Scanner offers unparalleled diagnostic capabilities for heavy-duty trucks. Beyond code reading, clearing, and live data display, it retrieves vehicle information, freeze frames, and DTCs. With 6, 9, and 16 pin cables, it ensures compatibility with various engines. This scanner's real-world testing prowess ensures comprehensive support for a wide array of heavy-duty truck engines, making it an indispensable tool for truck diagnostics
【DTC Library】+【Life Time Free Update】The built-in DTC library allows you to retrieve the codes directly without searching for the definition in the book. Whether you are a professional mechanic or a DIY car owner, HD601 diesel scanner explains the existing problem, makes it easier for you to understand code definitions and helps you locate vehicle faults. Note: This device cannot directly solve the fault. Plus, you get a lifetime free internet updates, so you always have the latest software for diagnostics in English and Spanish languages.
【Friendly Design, Easy of Use】This scanner is plug and play, simple and convenient, and very friendly for beginners. With improved buttons for easy menu navigation. The excellent 2.8 inch LCD color screen makes it easy to view the displayed results and gives you a better overview of your car's problem areas and the identified codes. In addition, the processor is super-fast and responds without lagging, providing maximum comfort and efficiency in diagnostic and service work

SaleBestseller No. 3

NEXAS Heavy Duty Truck Scanner NL102 Full System Diesel Truck Scan Tool for Cummins, Isuzu, Freightliner, Caterpillar, Detroit, Peterbilt, 2-in-1 Code Reader Read & Clear Fault Codes for Truck & Car

Why NEXAS NL102 Truck Scan Tool? The NL102 outshines other truck scanner with its extensive diagnostic features. It offers full system diagnostics for major trucks meeting standard protocols, along with complete OBD2 functionality. Beyond read fault codes, clear codes and live data display, it enables vehicle info retrieval, freeze frame capture, and DTC lookup. Equipped with 6-pin, 9-pin, 16-pin connectors, it ensures broad truck compatibility. Plus, enjoy lifetime free updates in English, Spanish, and French, keeping your diagnostic scanner software current.
Wide Compatibility - Friendly Reminder: To avoid compatibility issues, please confirm with us via Amazon Messages before purchasing. This heavy duty truck scanner is compatible with all heavy-duty trucks and semi that adhere to standard protocols (J1587, J1939, J1708). It covers a wide range of vehicle models, including Cummins, Detroit, Caterpillar, Freightliner, International, Kenworth, John Deere, Peterbilt, Sterling, Mack, Paccar, Western Star, Mercedes-Benz, Volvo, Scania, MAN, Renault, ERF, Foden, Seddon-Atkinson, Iveco, DAF, SISU, STEYR, ISUZU etc. Equipped with 6-pin, 9-pin, and 16-pin connectors for versatile device compatibility, ensuring stable plug-and-play connections.
Save Hundreds of Money for All Heavy Duty Trucks – This diesel diagnostic scanner supports accurate full-system scans for all heavy-duty trucks that comply with standard protocols (J1587, J1939, and J1708). It can read and clear trouble codes across a range of vehicle systems, including the engine, transmission, instrument panel, drivetrain, brake system, suspension, ABS, ESP, EPS, fuel system, etc. The truck scanner communicates directly with your truck's computer to provide real-time data stream analysis, letting you pinpoint issues with precision. This cuts down on waste from unnecessary part replacements, saving you time and hundreds or even thousands of dollars.
All OBD2 Functions + Battery Health Monitoring – Unlike many obd2 scanners on the market that only cover partial OBD2 features, ours gives you full OBD2 capability: read & clear codes, live data, freeze frame data, I/M readiness checks, EVAP tests, on-board monitor, O2 sensor tests, vehicle info, and DTC lookup. That means more detailed insights for pros and DIYers alike. The NL102 isn't just a code scanner – it's a battery saver. Regularly check your car's battery health, and catch issues before it dies completely. No more unexpected no-starts in the driveway or on the road. It diagnoses battery condition accurately, helping you avoid costly last-minute repairs.
Plug and Play & One-click for DTC: NEXAS diesel scanner is user-friendly. It comes with an intuitive screen and easy-to-understand interface, making it accessible even for non-professionals to get started. And the built-in DTC library in the code reader allows you to directly retrieve codes without searching for definitions in books, making it easier to understand the code definitions and solve problems more quickly.

This product presentation was made with AAWP plugin.

Last update on 2026-05-13 / Affiliate links / Images from Amazon Product Advertising API

Buffer Email Facebook Flipboard Hacker News LinkedIn Messenger Mix Pinterest Print Reddit SMS Telegram Tumblr X VK WhatsApp Line Xing Threads Bluesky Copy Mastodon Nextdoor