DTC 257

DTC 257 GENERATOR TEMPERATURE SENSOR CIRCUIT LOW

CIRCUIT DESCRIPTION

DTC Detection Condition:

The motor temperature sensor No. 2 detects the temperature of the transaxle fluid. The resistance of the thermistor installed in the motor temperature sensor No. 2 varies with the changes in the transaxle fluid temperature. The construction in the motor temperature sensor No. 2 and how it is connected to the HV control ECU are the same as those of the motor temperature sensor No. 1.




The resistance of the thermistor, which is enclosed in the motor temperature sensor No. 1, changes in accordance with the changes in the temperature of the motor. The lower the motor temperature, the higher the resistance of the thermistor. Conversely, the higher the temperature, the lower the resistance.
The motor temperature sensor No. 1 is connected to the HV control ECU. The power voltage of 5 V is supplied from the MMT terminal of the HV control ECU to the motor temperature sensor No. 1 via resistor R. Because resistor R and the motor temperature sensor No. 1 are connected in series, the resistance changes with the changes in temperature of the motor, which causes the MMT terminal voltage to also change. Based on this signal, the HV control ECU limits the load in order to prevent the motor from overheating. Furthermore, the HV control ECU checks the motor temperature sensor No. 1 for a wiring malfunction and the sensor for malfunction.

Based on the signal provided by the motor temperature sensor No. 2, the HV control ECU limits the load to prevent the motor from overheating. Furthermore, the HV control ECU checks the motor temperature sensor No. 2 for a wiring malfunction and the sensor for malfunction.






HINT: After confirming DTC P0A38 (INF 257) or P0A39 (INF 259), confirm MOTOR 2 TEMP in DIAGNOSIS / OBD/ MOBD / HV ECU / DATA LIST using the hand-held tester.

Wiring Diagram:

Step 1 - 2:

Step 2 (Continued) - 3:

Step 4 - 5:

Step 6:

INSPECTION PROCEDURE

CHECK FOR INTERMITTENT PROBLEMS

a. Perform a simulation test .
1. In the simulation test, reproduce the driving condition at the trouble occurrence according to the customer's comments and freeze frame data recorded with DTCs, such as an opening angle of the accelerator pedal, SOC, engine coolant temperature, engine rpm, and MG1/MG2 rpm and torque.

b. Check the connector(s) and terminal(s).
c. Wiggle the harness and connector(s).