Nissan U1025-00
Nissan U1025-00 — Service/Diagnostic Guide
Overview
- Item: Transmission control system diagnostic code U1025-00 (Nissan).
- Meaning: Communication error between the Transmission Control Module (TCM) and another control module (often ECM/PCM) — typically “Lost Communication With Transmission Control Module” or similar.
- Common causes: Faulty wiring/connector, power/ground issue, TCM failure, ECU/PCM fault, network (CAN) bus fault, intermittent connections after repairs, or software/incompatibility after module replacement.
Visual Inspection: Look for any loose connections or damaged wires near the rear wheels where the parking brake actuators are located.
- Measure voltage at CAN-H and CAN-L with ignition ON: typical idle voltages ~2.5V each; CAN-H ~3.5V, CAN-L ~1.5V during activity.
- With ignition OFF there should be no messages; with ignition ON and scan tool connected, watch for message activity.
- Check for proper 120Ω termination (two 60Ω resistors in parallel) across CAN-H/L when network powered.
It was a typical Monday morning at the Nissan dealership, with a steady stream of cars coming in for routine maintenance and repairs. One of the technicians, Alex, was assigned to work on a 2018 Nissan Altima that had been brought in by its owner, Sarah, due to a persistent issue with the car's engine performance. nissan u1025-00
Inspect the Connector: Unplug the connector at the turbocharger actuator. Look for green or white corrosion on the pins. Clean it with dedicated electrical contact cleaner. Nissan U1025-00 — Service/Diagnostic Guide Overview
RPM Limit: The engine might not rev beyond 2,000–2,500 RPM. Visual Inspection : Look for any loose connections
- Remove the ABS module from the hydraulic unit (do not open brake lines – unbolt the electronic part).
- Open the module case by cutting the silicone seal.
- Inspect the main circuit board for cracked solder joints on the large connector pins (especially the CAN pins).
- Reflow each joint with a soldering iron and fresh leaded solder.
- Seal the module with automotive-grade silicone and reinstall.
Severe Loss of Power: Since the ECM cannot control turbo boost, the car will feel extremely sluggish or "flat" during acceleration.
Conclusion