Coolant temperature sensor short circuit to ground
• Check connectors to BMU (E81) B9 and B12 • For FPC1(B) - Check wiring between BMU and water temperature sensor and harness connector C443 pin 11 and 12 - Disconnect the connector C443 an measure the resistance between pin 11 and pin 13 and between pin 11 and pin 18. - If the resistans is measureble(< OL) change the sensor T179 - If the resistance is infinite or OL, change the BMU(E81) • For FPC1(A) - Check wiring between BMU and water temperature sensor T179. - Disconnect the connector E81A and B and measure the resistance between pin B9 and pin A2 in the harness connector. - If the resistans is measureble(< OL) change the sensor T179 - If the resistance is infinite or OL, change the BMU(E81)
What you'll see
No driver-visible symptom recorded.
System reaction
The heater in the hybrid battery cooling circuit will not be allowed to start. This may result in degraded hybrid system performance when the ambient temperature is below 5ºC. The battery system will eventually get warm when the vehicle is used even without heater but this may take some time. During this time the hybrid system has degraded performance.
Diagnostic depth
Electrical error diagnosis in BMU
• Short circuit in connection to BMU • Short circuit in wiring between water temperature sensor and BMU • Short circuit in the water temperature sensor