Chart C7 - EGR Check: Notes

The ECM operates a solenoid to control vacuum to the EGR valve. This solenoid is normally closed. By providing a ground path, ECM energizes the solenoid, allowing vacuum to pass to the EGR valve. ECM control of the EGR is based on the following inputs:

• Engine coolant temperature greater than 77°F (25°C).
• TPS - off idle.
• MAP.

1. When ALDL "test" terminal is grounded, EGR solenoid is energized, allowing vacuum to be applied to EGR valve. Vacuum should hold.
2. When "test" terminal is ungrounded, vacuum to EGR valve should bleed off through solenoid vent. Valve should close. Vacuum gauge may or may not bleed off vacuum.
3. Determines if electrical control of system is at fault or if connector or solenoid is at fault.
4. Negative backpressure valve should hold vacuum with engine off.
5. When engine is started, exhaust backpressure should cause vacuum to bleed off and valve to fully close.