Air Switching System Diagnosis (Vacuum Supply)
- Remove vacuum hose for air switching/diverter valve and connect a vacuum gauge to hose. Set parking brake. Start engine and observe gauge reading.
- On a cold engine, engine vacuum should be present until engine coolant temperature reaches 60°F. When temperature is reached and time delay has elapsed as shown in Air Switching Delay Specifications table, vacuum should drop to zero. If no vacuum is present on gauge, check vacuum supply, air switching solenoid, coolant switch, charge temperature switch and computer wiring and connections. If all check okay, computer may be defective, preventing air switching function. Proceed to step 4.
- warm engine, vacuum should be present for the specified time shown in Air Switching Delay Specifications table after engine starts, then drop to zero. If there is no vacuum, check vacuum supply, air switching solenoid, coolant switch, charge temperature switch and computer wiring and connections. If all check okay, computer may be defective, preventing air switching function. Proceed to step 4 ).
- If no vacuum was recorded in steps 2 and 3 and all components are operating properly, connect a voltmeter to Light Green wire on air switching solenoid. With engine at normal operating temperature and engine off, start engine. Voltage should be less than 1 volt. After specified time shown in Air Switching Delay Specifications table, voltmeter should read the same as charging system voltage. If voltmeter does not register charging system voltage or charging system voltage is shown prior to specified time, replace computer.