If you’re experiencing issues with the IDSS diagnostic adapter losing communication with an ISUZU truck ECM, specifically a 2021 RG01 Euro 4JJ3 AWR6B45 Engine Control with DPD, here are some step-by-step troubleshooting tips to help you solve the problem:
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Step-by-Step Troubleshooting
- Scan Tool Power-Up Check
- Connect the scan tool to the diagnostic port.
- Check if the scan tool powers up.
- If it doesn’t, refer to the “Engine Control 1A.Troubleshooting(4JJ3 with DPD) Scan tool does not power up” section in your service manual.
- Scan Tool Communication Verification
- With the scan tool connected and powered up, turn on the ignition switch.
- Try to establish communication with the ECM using the scan tool.
- If communication fails, proceed to check the central gateway control unit communication.
- Central Gateway Control Unit Communication Verification
- Verify if the scan tool can communicate with the central gateway control unit.
- If there’s no communication, refer to the “Body Control 10I.Troubleshooting (Central Gateway) lost communication with the central gateway control unit”.
- Powertrain CAN Communication Circuit Verification
- Check communication with key control modules such as the battery sensor, TCCM, rear differential lock control unit, TCM, and the information module.
- If communication is not established with any module, inspect the powertrain CAN communication circuit as per the service manual.
- ECM Harness Connector Inspection
- Inspect the ECM harness connectors for poor connections.
- Refer to the ETM (wiring diagram) to support your inspection.
- Fuse Inspection
- Inspect fuses related to the ECM and engine control.
- Replace any blown fuses and investigate potential short circuits if fuses blow repeatedly.
- Ignition Power Supply Circuit Inspection
- With the ignition off and ECM disconnected, use a test lamp between the ignition power supply circuit and ground.
- Turn on the ignition and check if the test lamp illuminates.
- ECM Ground Inspection
- Check the ECM ground section for corrosion or improper installation.
- Repair as necessary if the ground is faulty.
- ECM Main Relay Inspection
- Replace the ECM main relay with a known good relay and check communication status.
- ECM Main Relay Voltage Supply Circuit Inspection
- With the ECM main relay removed, test the voltage supply and control circuit with a test lamp.
Keep progressing through each step as outlined in your initial diagnostic approach. Each step is crucial and should be conducted carefully to identify where the communication breakdown is occurring.
If you complete all the steps and still face issues, consider consulting with a professional technician or contacting ISUZU’s support for further assistance. This troubleshooting procedure is comprehensive and should cover the typical causes of communication issues between IDSS and the ECM.