1995 GMC Forward Control 4.3 Z, StandardFACTORY OEM SERVICE PROCEDURE

DTC 58: Transmission Fluid Temperature High: Notes

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 212Β°F (100Β°C), voltage will be about 1.5-2.0 volts.

NOTE: Test numbers refer to numbers on diagnostic chart.
  1. Code 58 will set if signal voltage indicates a transmission fluid temperature greater than 305Β°F (151Β°C) for one second.
  2. This test determines if circuit is shorted to ground, which will result in conditions for Code 58.
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
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  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

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