Code 58, Transmission Fluid Temperature High: Notes

WARNING: This page is about a different car, the 1995 GMC Sonoma and 1995 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.

Transmission fluid temperature sensor is a thermistor which controls signal voltage to control module. Control module applies and monitors voltage to sensor. When transmission fluid is cold, sensor resistance is high; therefore, control module will see high signal voltage. As 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.

NOTE: Test numbers refer to numbers on diagnostic chart.

Code 58 will set if signal voltage indicates a transmission fluid temperature greater than 305°F (151°C) for one second.
This test determines if circuit is shorted to ground, which will result in conditions for Code 58.