Discovery II
EMISSION CONTROL - V8
DESCRIPTION AND OPERATION 17-2-49
Test 3 – Vacuum Solenoid Valve
Function
The vacuum solenoid valve is energised for the duration of the secondary air injection. The valve is open when
energised, the intake manifold vacuum acts on the diaphragm of the SAI control valve and the control valve opens.
The solenoid valve is closed when de-energised.
Power Supply
Remove the harness connector from the vacuum solenoid valve and check the voltage between the connection
terminals. No voltage must be present at the connector after switching off the SAI pump.
Opening/Tightness
Disconnect the vacuum line at one of the SAI control valves and connect a hand vacuum pump to the line. With the
engine running at idle, a pressure difference of a minimum of 390 mbar (5.65 lbf/in
2
) must measurable on the hand
vacuum pump gauge with the vacuum solenoid valve energised.
The vacuum solenoid valve must be sealed when de-energised. If the Opening/tightness test fails, replace the
vacuum solenoid valv.
Test 4 – Delivery Hoses to Secondary air Injection (SAI) Control Valves
Visually inspect the delivery hoses to the SAI control valves for damage or blockage. If damage, condensate or
deposits are found the delivery hoses must be replaced. Check the hoses for correct connection and leaks.
Test 5 – Connection to Air Manifold
Check the connection for leaks visually or by using a leak detection spray. Reseal the connection if necessary.
Test 6 – Vacuum Lines
Visually inspect the vacuum lines for damage. Check each line for leaks or blockages using the vacuum hand pump.
Check the lines for correct connection.
