Code 58, Transmission Temperature Sensor Circuit (High Temperature Indicated) - LT. Truck: Notes

1992 GMC Rally Camper Special 6.2 JSECTION Notes
Fig 1: Trans. Temp. Sensor Circuit (Lt. Truck)
G91H13679Courtesy of GENERAL MOTORS CORP.

The transmission temperature sensor is a thermistor which controls the signal voltage to the PCM/TCM. The PCM/TCM applies and monitors voltage on circuit No. 1227 to the sensor. When transmission is cold sensor resistance is high; therefore, the PCM/TCM will see high signal voltage. As the transmission warms up, sensor resistance and voltage will drop. At normal transmission operating temperature of 212Β°F (100Β°C), voltage will be about 1.5-2.0 volts.

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