Secondary Air Injection System
FAULT DIAGNOSIS, SECONDARY AIR INJECTION SYSTEM
Fault Symptom.
Emissions affected
DIAGNOSTIC PROCEDURE
1. Checking The Fuses
Check MAX fuse 1 (air temp) and fuse 13 (boost pressure control valve). Both fuses are located in the front main fuse box.
If the fuses are OK, continue with point 2.
If any fuse is not OK, change the fuse.
2. Checking Valve Operation
Connect the Scan Tool.
Remove the secondary air injection relay.
Start the engine.
Select "READ FUNCTIONS".
Select "OXYGEN SENSOR".
When the oxygen control system is in operation, i.e. when the Scan Tool fluctuates between about 0.1 V and 0.9 V, connect a jumper lead across pins 30 and 87 of the relay base for 5-10 seconds.
The Scan Tool reading should not fluctuate but remain constantly below 0.45 V.
If the reading is OK, continue with point 7.
If the reading is not OK, continue with point 3.
3. Checking The Secondary Air Injection Relay And Secondary Air Injection Pump
Fit the secondary air injection relay. Ignition switch in the ON position.
Select "ACTIVATE".
Select "SECOND. AIR RELAY".
The command activates the relay at a frequency of 1.0 Hz for 10 seconds.
Listen for the sound of the air pump and relay working.
If the air pump and relay are working, continue with point 5.
If the air pump and relay are not working, continue with point 4.
4. Checking The Electrical Interfaces Of The Secondary Air Injection Relay And Air Pump
Ignition switch in the ON position.
Connect a test lamp to pin 30 of the relay base and a good grounding point.
The test lamp should light up.
If it does not, check wiring.
Ignition switch in the OFF position. Check The Wiring harness for continuity between:
- Pin 87 of the relay board and pin 2 of the air pump.
- Pin 1 of the air pump and grounding point G30.
If the leads are OK, the air pump connections to the power supply and ground are OK. If the air pump still does not work, change it.
If any lead is not OK, rectify the fault.
5. Checking The Boost Pressure Control Valve And Vacuum Valve
Remove fuse 13.
Start the engine and run it at idling speed.
Apply current to the boost pressure control valve by connecting battery positive to the output side of the fuse in the fuse holder.
Listen to the pump's inlet pipe. Exhaust noise can be heard when the valve is open. Nothing can be heard when the valve is closed.
If the valves are OK, check the lead between pin 87 of the relay base and the input side of fuse 13 in the fuse holder for continuity.
If the valves are not OK, continue with point 6.
6. Checking The Electrical Interfaces Of The Boost Pressure Control Valve
Remove the boost pressure control valve. Connect a test lamp to pins 1 and 2 of the valve's connector.
Select "ACTIVATE".
Select "SECOND. AIR RELAY".
The test lamp should flash.
If the test lamp flashes:
- Check the resistance of the boost pressure control valve. Nominal resistance is 40 ±5 ohms at 20°C. If the resistance is not OK, change the boost pressure control valve.
- Check the mechanical connections of the valves.
The boost pressure control valve opens ON/OFF when energized.
The vacuum valve opens ON/OFF when there is a vacuum.
When the vacuum valve is open a noise can be heard from the pump inlet.
If the test lamp does not flash:
- Check the lead between pin 1 of the boost pressure control valve and grounding point G30.
- Check the lead between pin 2 of the boost pressure control valve and pin 87 of the relay base for continuity/shorting.
7. Final Check
Drive the car on test and check whether the fault symptoms persist.
If the symptoms persist, refer to Before Replacing A Control Module.
If the symptoms have gone, the action taken to rectify the fault was correct, otherwise the fault is of intermittent nature.