Secondary Air Injection System (EMISSION CONTROL - V8) (page 4 of 8)

EMISSION CONTROL - V8

DESCRIPTION AND OPERATION 17-2-29

Secondary Air Injection (SAI) Vacuum Solenoid Valve

1 Vacuum port to intake manifold 

(via vacuum reservoir)

2 SAI vacuum solenoid valve
3 Electrical connector

4 Vacuum port to vacuum operated SAI control 

valves

5 Purge valve clip
6 Mounting bracket

The SAI vacuum solenoid valve is located at the rear LH side of the engine and is electrically operated under the 
control of the ECM. The SAI vacuum solenoid valve is mounted on a bracket together with the EVAP system purge 
valve.

Vacuum to the SAI vacuum solenoid valve is provided from the intake manifold depression via a vacuum reservoir. A 
small bore vacuum hose with rubber elbow connections at each end provides the vacuum route between the vacuum 
reservoir and SAI vacuum solenoid valve.  A further small bore vacuum hose with a larger size elbow connector is 
used to connect the SAI vacuum solenoid valve to the SAI control valves on each side of the engine via an 
intermediate connection.  The SAI vacuum solenoid valve port to the SAI control valves is located at a right angle to 
the port to the vacuum reservoir.  

The intermediate connection in the vacuum supply line is used to split the vacuum equally between the two SAI control 
valves. The vacuum hose intermediate connection is located midpoint in front of the inlet manifold. All vacuum hose 
lines are protected by flexible plastic sleeving.

Electrical connection to the SAI vacuum solenoid valve is via a 2–pin connector. A 12V electrical power supply to the 
SAI vacuum solenoid valve is provided via the Main relay and Fuse 2 in the engine compartment fusebox. The ground 
connection is via the ECM which controls the SAI vacuum solenoid valve operation. Note that the harness 
connector to the SAI solenoid valve is grey, and must not be confused with the harness connector to the 
EVAP system purge valve which is black.

The ECM switches on the SAI vacuum solenoid valve at the same time as initiating SAI pump operation. When the 
SAI vacuum solenoid valve is open, a steady vacuum supply is allowed through to open the two vacuum operated 
SAI control valves. When the ECM breaks the earth path to the SAI vacuum solenoid valve, the valve closes and 
immediately shuts off the vacuum supply to the two SAI control valves at the same time as the SAI pump operation 
is terminated.

M17 0211

1

4

2

3

5

6