Chart C-6 Air Management Check (PEDES Valve) - PFI

Chart C-6:

Chart C-6 Wiring Diagram:

CIRCUIT DESCRIPTION:

The air management system is controlled by a pressure operated port and an air switching valve (converter valve). Both valves are controled by the ECM. Pump air will be directed as follows:

During cold start, the port solenoid is energized, which opens the port valve, and air is directed into the exhaust ports. As coolant temperature increases, or system goes into "Closed Loop", the port solenoid is de-energized, and the converter solenoid is powered, which allows the converter valve to be seated, and air is forced to the catalytic converter. If both solenoids are powered off, the air will be diverted to the atmosphere.


TEST DESCRIPTION: The numbers below refer to circled numbers on the diagnostic chart.

1. This is a system functional check. Since all engines start in open loop, air is directed into the ports. Squeeze the air hose prior to starting the engine to check port air operation.

2. This should set a code 22. When any code is set, the ECM opens the ground to the converter solenoid, and allows air to divert. This checks for ECM response to a fault. A ground in the control valve circuit to the ECM would prevent the divert action.

3. This checks for a grounded circuit to the ECM. Test light off is normal and indicates circuit is not grounded.

4. This checks for an open in the solenoid control circuits. Grounding the test terminal, should ground both solenoid circuits. Normally, the test light should be on. this indicates that the problem is not in the ECM or wiring, but at the solenoid connections or valve itself.

5. This checks for a grounded solenoid circuit. Test light off indicates that the circuit is normal, and the fault is in the valve.

NOTE: Once the test sequence is completed, clear codes and verify NO "SERVICE ENGINE SOON" light exists.