Code 59, Transmission Temp. Sensor CKT (Low Temp. Indicated): Notes
WARNING: This page does not describe the selected car, but rather 24 other vehicles, including the 1992 GMC Yukon, 1992 GMC Vandura Special, 1992 GMC Vandura, 1992 GMC Value Van, and 1992 GMC Suburban. However, it is still accessible from the selected car via links, so may be relevant.
The transmission temperature sensor is a thermistor which controls signal voltage to PCM/TCM. The PCM/TCM applies and monitors 5 volts to the sensor on circuit No. 1227. When transmission is cold, sensor resistance is high; therefore, the PCM/TCM will see high signal voltage. As transmission temperature warms up, sensor resistance and voltage 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 test numbers on diagnostic chart.
- Code 59 will set if signal voltage indicates a transmission temperature less than -54°F (-48°C) for one second.
- This test simulates Code 58. If PCM/TCM recognizes the low signal voltage (high temperature) and scan tester reads 304°F (151°C) or greater, the PCM/TCM and wiring are okay.
- This test determines if circuit No. 1227 is open. There should be 5 volts present at the sensor connector if measuring with a DVOM.