DTC 58

DTC 58 Transmission Fluid Temperature Sensor Circuit (High):

Transmission Fluid Temperature Sensor Circuit:

Circuit Description:
The transmission fluid temperature sensor is a thermistor within the fluid pressure switch assembly, that controls the signal voltage to the PCM. The PCM applies voltage on CKT 1227 to the sensor. When the transmission fluid is cold, the sensor resistance is high and the PCM will sense high signal voltage.
As the transmission fluid temperature warms to normal transmission operating temperature 100°C (212°F), the sensor resistance becomes less and the voltage decreases to 1.5 to 2.0 volts. With a DTC 79 also set, check the transmission cooling system.
When DTC 58 is set, the transmission will use a warm value for operation, but the scan tool will display the actual fluid temperature.

Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. DTC 58 will set if:
^ Signal voltage indicates a transmission fluid temperature above 154°C (309°F) for 1 second.
2. This test checks if CKT 1227 is shorted to ground which will cause the conditions for DTC 58.

Diagnostic Aids:
^ Check harness routing for a potential short to ground in CKT 1227.
^ Scan tool displays transmission is operating, the temperature should rise steadily to about 100°C then stabilize.
^ Refer to "Diagnosis By Symptom." Testing and Inspection
^ The temperature to resistance value scale at the right, may be used to test the transmission sensor at the various temperature levels to evaluate the possibility of a "skewed" sensor. A "skewed" sensor could result in delayed garage shifts or TCC enabled complaints.