DTC 53

TEST DIAGRAM

AIR Vacuum Switching Valve Test Diagram:

TEST DESCRIPTION

1. Disconnect vacuum switching valve (VSV) connector and check resistance across VSV terminals. It should be over 40 ohms but less than infinity.

2. If less than 40 ohms; replace VSV, clear codes, run engine and recheck. If code 53 reappears, the ECM should be replaced if no connector or wiring problems exist. If code 53 does not reappear, perform the System Performance Check.

3. If more than 40 ohms; turn ignition "ON" (engine not running) and ground diagnostic connector (ALDL). With VSV disconnected, probe harness terminal "12" with a test light. If the light does not come on, check and repair the circuit as needed.

4. With one side of test light connected to battery "+" probe harness terminal "13." Light should come on if ECM is properly grounding the circuit and no wiring problems exist. If not, check wiring and connectors back to ECM before concluding that the ECM itself is defective.

5. A quick check can be performed as follows: ground diagnostic connector and turn ignition "ON" and "OFF." VSV should "click" each time it is energized and de-energized if ECM and wiring are functioning properly.