Nissan/Infiniti ECU/ECM

Nissan/Infiniti ECU/ECM Post-Repair Troubleshooting Guide (No-Start / No-Communication)

Important: Use this guide if you reinstalled your repaired Nissan/Infiniti ECU/ECM and the problem is still happening.

Important: Please do not open/disassemble the module. This can damage the unit and may void warranty coverage.

Step 1: Confirm correct ECU + install basics

• Confirm the ECU part number matches your original unit
• Make sure ECU is mounted and connectors are fully latched/locked

Step 2: Battery voltage first

• Fully charge the battery (low voltage can cause no-start and no-comm)
• Disconnect battery negative for 10 minutes, reconnect, then key ON and retry

Step 3: Check ECU fuses and ECU relay

• Check ALL fuses related to ECU/EFI/IGN/INJ/ECM (engine bay + interior)
• Swap the ECM/EFI relay with a same-type relay if possible

Step 4: Inspect ECU connectors (common)

• Key OFF
• Unplug ECU connectors and inspect for:
• Bent pins / pushed-back pins
• Corrosion or moisture
• Damaged connector locks
• Re-seat connectors until they click/lock fully

Step 5: Verify ECU power and grounds (most important)

• Have a shop verify at the ECU connector:
• Constant battery power feed(s)
• Ignition-switched power feed(s)
• Strong ground(s)
• Inspect/clean battery terminals and main engine/chassis ground points

Step 6: If scan tool won’t talk to ECU

• Confirm the scan tool communicates with other modules
• If NOTHING communicates, check:
• OBD-II port power fuse
• CAN wiring/shorts (recent stereo/alarm work is a common cause)

Step 7: If ECU communicates but still no-start

• Check for spark, injector pulse, and fuel pressure
• Confirm crank/cam sensors are plugged in and wiring isn’t damaged
• Re-check any recent work (battery, starter, harness, grounds, fuses)

Step 8: What to send UpFix if the issue continues

• VIN
• Full code list (all modules)
• Does the scan tool connect to other modules? (Yes/No)
• Any recent wiring/engine work, jump-start, or water intrusion