Solenoid Controlled Vacuum Operated EFE System Check

CAUTION: Do not ground ECM test terminal unless instructed to do so in procedure.

1. Check vacuum hoses and connections, disconnect coolant sensor, then connect vacuum gauge in place of EFE valve.
2. Start engine and note vacuum reading at idle.
3. If vacuum reading is below 10 inches Hg proceed as follows:
a. Stop engine, disconnect EFE connector, then connect test light between connector terminals A and B. With ignition "ON", ground ECM test terminal and note test light.
b. If light is on, check vacuum source to EFE solenoid. If the vacuum source is OK, the EFE solenoid or solenoid connection is defective.
c. If light is OFF, connect test light from terminal B (pink wire) to ground and note test light.If light is off, repair open in pink wire circuit. If light is ON, check for open in wire to ECM terminal B on 1981 vehicles or terminal 6 on 1982 vehicles. On 1982 vehicles, check resistance of EFE solenoid. If resistance is under 20 ohms, replace solenoid and ECM; if above 20 ohms, the ECM connector or ECM is defective.
4. If vacuum reading is above 10 inches H after performing Step 2, proceed as follows:
a. Connect coolant sensor and note vacuum gauge reading. It should drop to zero within one minute.
b. If vacuum reading does not drop, disconnect EFE connector and connect test light between connector terminals A and B. With ignition "ON" and engine off, note test light. If test light is off, replace EFE solenoid. If test light is on, check for grounded wire to ECM terminal 6 or defective ECM.
c. If vacuum reading drops, stop engine and apply 10 inches Hg vacuum draw to EFE valve, while listening for valve movement as vacuum is released.
5. If valve does not move, check for leaking or restricted EFE vacuum line and/or defective EFE valve.
6. If valve moves, disconnect vacuum hose connections from solenoid and connect vacuum gauge to check valve hose. Vacuum should rise quickly and fall slowly as engine is started and stopped.
- If vacuum is as noted, the EFE system is working properly.
- If vacuum is not as noted, replace check valve.