11-08-2009, 04:21 PM
True Car Nut
Join Date: Sep 2008
Location: Arlington, WA
Secondary Air Injection (AIR) system.
The control module activates the Secondary Air Injection System by grounding both the pump relay and the vacuum control solenoid control circuits simultaneously. This energizes the pump and the vacuum control solenoid. Vacuum is then applied, opening the valves. The pump then force fresh air into the exhaust system in order to accelerate catalyst operation. The control module will run up to 3 diagnostic tests using the pre-catalyst HO2S voltage and Short Term Fuel Trim (FT) to diagnose the system.
- The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostics test has been run and failed.
- The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records Data.
- If the misfire is determined to be catalyst damaging, the PCM will flash the MIL.
- The pre-catalyst HO2S voltage remains above a predetermined lean value during the test AND
- The Short Term FT does not increase a calibrated amount during the test.
- Both conditions above exist for 3 consecutive tests.
- Visually inspect for the following:
- Loose or restricted AIR pipes/hoses
- Loose or restricted vacuum lines
- If problems found, correct and clear the DTC.
- If problems not found a scan tool will be needed to command air pump relay ON and OFF
- From this point forward, 42 separate tests are required to isolate the DTC from a vacuum or AIR pump problem associated with the relays, command modules and feed circuits.
- Check feed fuses and replace. If fuse fails again, a diagnostic via a TECH II is recommended.