Code 58, Trans Fluid Temp. Sens CKT (High Temp. Indicated): Notes

The transmission fluid temperature sensor, located within the fluid pressure switch assembly, is a thermistor which controls the signal voltage to the PCM. The PCM applies and monitors voltage on circuit No. 1227 to the sensor. When transmission fluid is cold, sensor resistance is high; therefore, the PCM will see high signal voltage.

As the transmission fluid warms, sensor resistance and voltage will drop. At normal transmission operating temperature of 212°F (100°C), voltage will be about 1.5-2.0 volts. If Code 79 is also present, check the transmission cooling system. When Code 58 is set, transmission will use a warm value for operation, but scan tester will display the actual fluid temperature.

1. Code 58 will set if signal voltage indicates a transmission fluid temperature greater than 309°F (154°C) for one second.
2. This test determines if circuit No. 1227 is shorted to ground, which will result in conditions for Code 58.