On Board Diagnostics II PCED

1999 PCED On Board Diagnostics II

SECTION 5: Pinpoint Tests

HM: Secondary Air Injection (AIR) System

HM: Introduction

HM1 CHECK B+ VOLTAGE TO SOLID STATE RELAY

Diagnostic Trouble Code (DTC) P0412 indicates EAIR primary circuit fault.

Disconnect SSR.
Key on, engine off.
Measure voltage of B+ circuit at SSR harness connector and battery negative post.

Is voltage greater than 10.5 volts?

Yes	No
Supplied voltage is OK, GO to HM2 .	GO to HM6 .

HM2 CHECK EAIR CIRCUIT FOR OPEN IN HARNESS

Key off.
Disconnect AIR bypass solenoid.
Remove Secondary Air Injection System dedicated fuse temporarily.
Disconnect PCM.
Measure resistance of EAIR circuit between PCM harness connector pin and SSR harness connector and AIR bypass harness connector.

Is resistance less than 5.0 ohms?

Yes	No
GO to HM3 .	REPAIR open circuit.

HM3 CHECK EAIR CIRCUIT FOR SHORT TO POWER AND GROUND WITH DISCONNECT AIR BYPASS SOLENOID

Measure resistance between EAIR and VPWR circuits at the PCM harness connector.
Measure resistance between EAIR at the PCM harness connector and battery negative post.

Is each resistance greater than 10,000 ohms?

Yes	No
The EAIR harness is OK. GO to HM4 .	REPAIR short circuit.

HM4 CHECK EAIR CIRCUIT FOR SHORT TO POWER AND GROUND

Reconnect AIR bypass solenoid.
Measure resistance between EAIR and VPWR circuits at the PCM harness connector.
Measure resistance between EAIR at the PCM harness connector and battery negative post.

Is each resistance greater than 10,000 ohms?

Yes	No
EAIR circuit with AIR bypass solenoid OK. GO to HM5 .	REPLACE AIR bypass solenoid.

HM5 CHECK EAIR CIRCUIT FOR SHORT TO POWER AND GROUND WITH SOLID STATE RELAY RECONNECTED

AIR bypass solenoid disconnected.
Reconnect solid state relay.
Measure resistance of EAIR circuit between VPWR and PWR GND circuits at the PCM harness connector.

Is each resistance greater than 10,000 ohms?

Yes	No
If DTC P0411 is present: GO to HM9 . All others: GO to HM14 .	REPLACE solid state relay.

HM6 CHECK B+ CIRCUIT FOR OPEN IN HARNESS

Measure resistance of B+ circuit between solid state relay harness connector and Secondary Air Injection System dedicated fuse.

Is resistance less than 5.0 ohms?

Yes	No
REPLACE Secondary Air Injection System dedicated fuse, then GO to HM8 to check electric AIR pump. RECONNECT solid state relay.	REPAIR open circuit. RECONNECT solid state relay and fuse.

HM7 VISUALLY INSPECT ELECTRIC AIR PUMP HOSES

DTC P0411 indicates Secondary Air not detected. In order to test the pump, it must be capable of driving the HO2S lean.

Visually inspect electric AIR pump hoses from the electric AIR pump to the AIR diverter valves.
Inspect air hose for cracks, binding, obstructions, water or ice.

Are electric AIR pump hoses OK?

Yes	No
GO to HM8 .	DRAIN all water from hoses or REPLACE damaged parts.

HM8 CHECK ELECTRIC AIR PUMP OPERATION

Key on, engine off.
Enter Output Test mode.

Does the pump run?

Yes	No
GO to HM15 to check electric AIR pump for water contamination.	REPLACE air hose to AIR diverter valves for leaks or blockage. If OK, GO to HM11 .

HM9 CHECK FOR VACUUM AT AIR DIVERTER VALVES

Connect a vacuum gauge to the control vacuum hose at the AIR diverter valve(s).
Apply 53 kPa (16 in-HG) of vacuum to source side of AIR bypass solenoid at the intake manifold.
Key on, engine off.
Enter Output Test mode.

Is vacuum present at the AIR diverter valve(s)?

Yes	No
GO to HM10 .	GO to HM30 .

HM10 CHECK AIR DIVERTER VALVE(S) INTEGRITY

CAUTION: Caution must be observed while performing this test.

Note: On a two valve system, make sure air is flowing from both valves.

Reconnect vacuum control line.
Disconnect air tube from AIR diverter valve(s).
Inspect AIR diverter valve(s) outlets for damage from hot exhaust gases. Repair as necessary.
Key on, engine off.
Enter Output Test mode.

Is air present from the AIR diverter valve(s)?

Yes	No
GO to Powertrain/Engine Group of the Workshop Manual to repair the exhaust tubes from the AIR diverter valve to the exhaust manifold(s). COMPLETE PCM Reset to clear DTCs. RESTORE vehicle. RERUN Quick Test.	REPLACE hose from electric AIR pump to AIR diverter valve. If OK, REPLACE the appropriate AIR diverter valve(s). COMPLETE PCM Reset to clear DTCs. RESTORE vehicle. RERUN Quick Test.

HM11 CHECK VOLTAGE ON EAIR MONITOR CIRCUIT

Disconnect electric AIR pump.
Key on, engine off.
Enter Output Test mode.
Measure voltage of EAIR monitor circuit between electric AIR pump harness connector and battery negative post.

Is voltage greater than 10.5 volts?

Yes	No
GO to HM13 .	GO to HM12 .

HM12 CHECK ELECTRIC AIR PUMP GROUND FOR OPEN IN HARNESS

Measure resistance of EAP ground circuit between electric AIR pump harness connector and battery negative post.

Is resistance less than 5 ohms?

Yes	No
GO to HM19 .	REPAIR open circuit.

HM13 CHECK AIR HOSE TO ELECTRIC AIR PUMP

Disconnect inlet air hose.
Visually inspect inlet air hose for binding, obstructions, water or ice to the electric AIR pump.

Is the hose integrity or orientation OK?

Yes	No
GO to HM15 .	DRAIN all water from air hose. REPLACE or RE-ORIENT hose as appropriate. GO to HM15 .

HM14 CHECK SOLID STATE RELAY OUTPUT

Reconnect AIR bypass solenoid.
Connect PCM.
Key on, engine off.
Enter output test mode.
Access AIR PID.
Access AIRM PID.
Compare AIR and AIRM PIDs.

Were both PIDs on?

Yes	No
REPLACE solid state relay.	REPLACE PCM (refer to Section 2 , Flash EEPROM).

HM15 CHECK AIR PUMP FOR WATER

Note: Water ingested in the electric AIR pump will reduce the life of the pump.

Disconnect electric AIR pump connector and air hoses.
Carefully tilt electric AIR pump in various positions to verify if any water is present.

Is any water present?

Yes	No
REPLACE electric AIR pump.	If fuse was replaced in HM6 , Testing is complete. All others, GO to HM9 .

HM17 CHECK B+ CIRCUIT VOLTAGE TO SOLID STATE RELAY

DTC P1413 indicates EAIR monitor circuit is low while the electric AIR pump was commanded ON.

Disconnect solid state relay.
Key on.
Measure voltage of B+ circuit between solid state relay harness connector and chassis ground.

Is voltage greater than 10.5 volts?

Yes	No
GO to HM18 .	GO to HM24 .

HM18 CHECK FOR VPWR TO SOLID STATE RELAY

Key on, engine off.
Measure VPWR circuit voltage at the solid state relay harness connector.

Is voltage greater than 10.5 volts?

Yes	No
GO to HM19 .	For LS6/LS8 : GO to Pinpoint Test Step B5 . All others : REPAIR open VPWR circuit between the solid state relay and Electronic Engine Control power relay (and dedicated fuse on LS6/LS8)..

HM19 CHECK VOLTAGE ON EAIR MONITOR CIRCUIT

Reconnect solid state relay.
Disconnect electric AIR pump.
Key on, engine off.
Enter output test mode.
Access AIRM PID.

Is PID on?

Yes	No
GO to HM23 . REMAIN in output test mode.	If DTC P0411 is present, REPLACE electric AIR pump. GO to HM20 . REMAIN in output test mode.

HM20 CHECK EAIR MONITOR VOLTAGE TO PCM

Disconnect PCM.
Key on, engine off.
Access AIRM PID.

Is PID on?

Yes	No
REPLACE PCM (refer to Section 2 , Flash EEPROM).	GO to HM21 .

HM21 CHECK EAIR DRIVER AND EAIR MONITOR CIRCUITS FOR OPEN IN HARNESS

Disconnect solid state relay.
Measure resistance of EAIR driver circuit between PCM harness connector and solid state relay harness connector.
Measure resistance of EAIR monitor circuit between PCM harness connector and solid state relay harness connector.
Measure resistance of EAIR monitor circuit between the solid state relay harness connector and the electric AIR pump harness connector.

Is each resistance less than 5.0 ohms?

Yes	No
GO to HM22 .	REPAIR the circuit in question.

HM22 CHECK EAIR MONITOR CIRCUIT FOR SHORT TO GROUND IN HARNESS

Measure resistance between EAIR monitor and PWR GND circuits at the PCM harness connector.

Is each resistance greater than 10,000 ohms?

Yes	No
REPLACE solid state relay.	REPAIR short circuit.

HM23 CHECK EAIR MONITOR VOLTAGE TO PCM

Reconnect electric AIR pump.
Reconnect PCM.
Key on, engine off.
Access AIRM PID.

Is PID on?

Yes	No
REPLACE PCM (refer to Section 2 , Flash EEPROM).	REPAIR open EAIR circuit.

HM24 CHECK B+ CIRCUIT FOR OPEN IN HARNESS

Measure resistance of B+ circuit between solid state relay harness connector and dedicated fuse B+ circuit.

Is resistance less than 5 ohms?

Yes	No
REPLACE solid state relay dedicated fuse.	REPAIR open circuit.

HM25 CHECK EAIR MONITOR CIRCUIT FOR OPEN IN HARNESS

DTC P1414 indicates electric AIR pump commanded off, but PCM indicates electric AIR pump is on.

Disconnect solid state relay.
Disconnect PCM.
Disconnect electric AIR pump.
Measure resistance of EAIR monitor circuit between PCM harness connector and electric AIR pump harness connector.

Is resistance less than 5 ohms?

Yes	No
GO to HM26 .	REPAIR open circuit.

HM26 CHECK ELECTRIC AIR PUMP FOR OPEN

Measure electric AIR pump resistance.

Is resistance between 0.5-5.0 ohms?

Yes	No
GO to HM27 .	REPLACE electric AIR pump.

HM27 CHECK EAIR MONITOR CIRCUIT FOR SHORT TO POWER IN HARNESS

Key on.
Measure voltage between PCM harness connector and chassis ground.

Is voltage greater than 10.5 volts?

Yes	No
REPAIR short circuit.	EAIR Monitor circuit is OK. GO to HM28 .

HM28 CHECK SOLID STATE RELAY OUTPUT

Reconnect AIR bypass solenoid.
Connect PCM.
Key on, engine off.
Enter output test mode.
Access AIR PID.
Access AIRM PID.
Compare AIR and AIRM PIDs.

Were both PIDs on?

Yes	No
REPLACE solid state relay.	REPLACE PCM (refer to Section 2 , Flash EEPROM).

HM30 CHECK VACUUM HOSE INTEGRITY

Key off.
Check vacuum hose between AIR bypass solenoid and AIR diverter valve.
Check for blockage and restrictions.
Check for leaks and cracks.
Check for kinks or disconnects.

Are the above checks OK?

Yes	No
GO to HM31 .	REPLACE the vacuum line connecting the AIR bypass solenoid to AIR diverter valve(s).

HM31 CHECK AIR BYPASS SOLENOID ELECTRICAL OPERATION

Key on, engine off.
Access Output Test Mode.
Disconnect AIR bypass solenoid.
Connect digital multimeter to AIR bypass solenoid vehicle harness connector.
Turn the outputs on, then turn outputs off while observing digital multimeter.

Does EAIR circuit voltage cycle greater than 0.5 volt?

Yes	No
REMAIN in Output Test Mode. GO to HM32 .	Key off. GO to HM33 .

HM32 CHECK AIR BYPASS SOLENOID FOR MECHANICAL OPERATION

Reconnect AIR bypass solenoid.
Disconnect source vacuum hose from AIR bypass solenoid.
Apply 53 kPa (16 in-Hg) of vacuum to source side of AIR bypass solenoid.
Turn the outputs on, then turn outputs off.

Was vacuum released?

Yes	No
REPAIR vacuum hose from manifold vacuum tree to AIR bypass solenoid.	REPLACE AIR bypass solenoid.

HM33 CHECK AIR BYPASS SOLENOID RESISTANCE

Disconnect AIR bypass solenoid harness connector.
Measure AIR bypass solenoid resistance.

Is resistance between 50 and 100 ohms?

Yes	No
GO to HM34 ,	REPLACE AIR bypass solenoid.

HM34 CHECK VPWR CIRCUIT FOR OPEN IN HARNESS

Key on, engine off.
Measure VPWR circuit voltage at the AIR bypass solenoid harness connector.

Is voltage greater than 10.5 volts?

Yes	No
GO to HM35 .	REPAIR open VPWR circuit (and dedicated fuse on LS6/LS8).

HM35 CHECK EAIR CIRCUIT FOR OPEN IN HARNESS

Disconnect solid state relay.
Disconnect PCM.
Measure resistance of EAIR circuit between PCM harness connector and the AIR bypass solenoid harness connector and at the solid state relay harness connector.

Is resistance less than 5.0 ohms?

Yes	No
GO to HM36 .	REPAIR open EAIR circuit.

HM36 CHECK EAIR CIRCUIT FOR SHORT TO GROUND IN HARNESS

Measure resistance between EAIR and PWR GND circuits at the PCM harness connector.

Is resistance greater than 10,000 ohms?

Yes	No
GO to HM37 .	REPAIR short to ground.

HM37 CHECK EAIR CIRCUIT FOR SHORT TO POWER IN HARNESS

Measure resistance between EAIR and PWR GND circuits at the PCM harness connector.

Is each resistance greater than 10,000 ohms?

Yes	No
REPLACE PCM (refer to Section 2 , Flash EEPROM).	REPAIR short to power.