Test Description
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- Code 23 will be set if the following conditions are met:
- Signal voltage indicates manifold air temperature below -22°F (-30°C) for 12 seconds.
- Time since engine start is one minute or longer.
- No vehicle speed sensor reading (vehicle stationary).
- A Code 23 will set due to an open sensor, wire, or connection. This test will determine if wiring and ECM are okay.
- This determines if signal circuit No. 472 or the 5-volt return circuit (No. 452) is open.