Air Injection: Testing and Inspection

Fig. 028 - Wiring Diagram for Air Management Check. VIN 8:

CHART C-6, AIR MANAGEMENT CHECK

Air Management is controlled by Air Control and Air Switching Valves, each with an ECM controlled vacuum solenoid. When the solenoid is grounded by the ECM, manifold vacuum will activate the valve and allow pump air to be directed as follows:
a. Air control solenoid not grounded by ECM - Air diverted to air cleaner.
b. Air control solenoid grounded by ECM - Air to Air Switching Valve.
c. Air switching solenoid not grounded by ECM - Air to converter.
d. Air switching solenoid grounded by ECM - Air to exhaust port.

Fig. 027 Chart C-6 - Air Management Check:

Fig. 029 Chart C-6A - Air Management Check:

1. This is a system functional check. Engine coolant temperature must be below 61°C (150°F). This step checks for air switching from port to converter. Since the air to port time is very short on some engines, prepare to check for air to ports immediately after engine starts.
2. This will set a Code 42. When a code is set, the ECM opens the ground to the Air Control Valve and allows air to divert. This checks for ECM response to a system fault.
3. This checks for a grounded circuit to the ECM. Test light "OFF" is normal and would indicate the circuit is not grounded.
4. Solenoids are turned "ON" or "OFF" by the ECM internal electronic switches called "drivers". Each driver is part of a group of four called "Quad-Drivers". Failure of one can damage any other driver within the set.
Solenoid coil resistance must measure more than 20 ohms. Less resistance will cause early failure of the ECM "DRIVER". Using an ohmmeter, check the solenoid coil resistance of the following before installing a replacement ECM.
a. Canister Purge
b. Air Switch
c. Air Divert