2.5L & 4.3L Turbo
WARNING: This page does not describe the selected car, but rather 25 other vehicles, including the 1992 Oldsmobile Bravada, 1992 GMC Vandura Special, 1992 GMC Vandura, 1992 GMC Value Van, and 1992 GMC Sonoma. However, it is still accessible from the selected car via links, so may be relevant.
The ECM supplies and monitors a voltage signal (4-6 volts) to the sensor. When temperatures are low, sensor resistance is high and the ECM will see a high-monitored voltage signal. As temperature increases, sensor resistance decreases and voltage sensed by the ECM drops.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- This checks if Code 23 is a hard failure or an intermittent condition. Code 23 will set if engine is running for one minute, MAT sensor temperature is less than -22°F (-30°C) for 12 seconds and speed sensor signal is not present.
- This simulates conditions for a Code 25. If the Scan tester displays a high temperature, the ECM and wiring are not at fault.
- This checks for continuity of sensor signal and ground circuits.