IPM to ECM CAN Communication Lost

Common Symptoms

• IPM panel LCD displays E070 and may show 'COMM FAULT' or 'ECM LOSS' alongside
• Unit cranks but shuts down immediately or fails to reach RUN state
• Engine RPM reads zero or dashes on the IPM panel display even while engine is running
• No engine data (oil pressure, coolant temp, RPM) updating on the IPM panel LCD
• Unit may cycle between crank attempts and shutdown without holding RUN
• Yellow or red fault indicator illuminates on the panel; STOP is triggered automatically
• Air delivery drops to zero because the compressor never loads after crank

Probable Causes (Ranked by Likelihood)

• Damaged, corroded, or loose J1939 CAN wiring harness connector at the ECM or IPM panel end Very Likely
• Blown or missing fuse on the CAN power supply or ECM ignition circuit Very Likely
• Failed or intermittently faulty engine ECM not responding on the J1939 CAN bus Likely
• Broken, shorted, or water-invaded CAN Hi / CAN Lo wire pair between IPM and ECM Likely
• Missing or incorrect 120-ohm CAN termination resistor at one or both bus ends Possible
• IPM panel firmware mismatch or corrupted configuration after a power event Possible
• Ground offset between IPM chassis ground and ECM chassis ground causing CAN signal loss Less Likely

Step-by-Step Diagnostic Procedure

1. Start with a full visual inspection. Open the electrical enclosure and trace the wiring harness from the IPM panel to the engine ECM. Look for chafed insulation, pinched wires at frame crossmembers, melted spots near exhaust, and pulled-out pins at any Deutsch or AMP connector. Repair any visible damage before proceeding.

2. Check the CAN-related fuses. Locate the fuse panel on the IPM enclosure and identify the ECM ignition supply fuse and any dedicated CAN or controller power fuse. Pull each one and inspect. Replace any blown fuse with the correct amperage rating marked on the panel label. Do not upsize.

3. Verify ECM battery voltage. With the ignition key at RUN (engine not cranking), measure DC voltage at the ECM battery supply pins on the harness connector. You should see 12.0-12.6 V DC on a 12V system or 24.0-25.5 V DC on a 24V system. Low voltage here means the ECM never powers up and cannot communicate on J1939 CAN.

4. Check chassis ground integrity. Measure resistance between the IPM panel chassis ground stud and the ECM chassis ground stud directly. Resistance should be under 0.5 ohms. A reading above 1 ohm means you have a bad ground path. Clean and retorque both ground connections at the battery negative, frame, and ECM block ground.

5. Measure CAN bus resistance. With the engine off and both ECM and IPM panel connectors unplugged, set your multimeter to resistance mode. Measure across the CAN Hi and CAN Lo wires at the harness midpoint. A healthy two-node J1939 CAN bus reads approximately 60 ohms (two 120-ohm terminating resistors in parallel). A reading near 120 ohms means one terminator is missing or one node is disconnected. A reading near zero ohms means there is a short between CAN Hi and CAN Lo.

6. Seat and clean all connectors. Unplug the main harness connector at the ECM and at the IPM panel. Inspect each pin for corrosion, pushed-back terminals, or moisture. Use electrical contact cleaner and a pin probe to clean contacts. Reseat firmly until the connector latch clicks. Cycle power and recheck for E070.

7. If the wiring and power supply check out and E070 persists, connect the engine OEM diagnostic tool (Cummins INSITE, John Deere Service Advisor, or Doosan dealer tool depending on your engine) to the engine ECU diagnostic port. Verify the ECM is active and broadcasting J1939 messages. If the ECM shows active but the IPM panel still reads E070, the fault is in the IPM panel itself or the harness between them. At this point, contact a Doosan-authorized service tech for IPM panel replacement or reconfiguration.

Frequently Asked Questions