Fault Phenomenon: Caterpillar 950 wheel loader instrument displays abnormally high transmission temperature, machine automatically enters protection mode and limits speed.

Troubleshooting Process:
– Checked sensor: resistance measurement out of range.
– Checked wiring: connector water ingress, oxidation, or harness worn, short to ground.
– Checked actual temperature: infrared thermometer shows normal transmission housing temperature.
– Checked controller: TCU receiving incorrect signal.

Root Cause: The internal thermistor of the transmission oil temperature sensor drifted, sending an erroneous high-temperature signal to the controller.

Required Parts: Replace transmission oil temperature sensor.