Pump Injection (5.9L)
- Inspect air pump drive belt and system hoses. Turn engine off and disconnect hoses at air injection upstream and downstream check valves. Start engine. Exhaust gases should not pass out of check valves. Replace valves as necessary.
- Start engine and check for presence of manifold vacuum at air control valve. If vacuum is not present, check for disconnected or plugged vacuum hose. Disconnect vacuum hose from control valve. After 5 seconds, reconnect hose. Air should be discharged from by-pass port on control valve for 1-2 seconds.
- When vehicle is cold, air injection should be delivered to upstream check valves. After vehicle has reached normal operating temperature, air injection should be delivered to downstream check valve.
- If not, check Dual Coolant Temperature Override (DCTO) switch for plugged bleed filter, no vacuum supply, or failure to switch vacuum with change from cold to hot operation. No testing procedures or specifications for DCTO are supplied by manufacturer.