Chart C-7 Exhaust Gas Recirculation (EGR) System Check

EGR Circuit:

Circuit Description
The EGR valve is controlled by a normally open regulator with a normally open air bleed. The ECM signals the regulator to control the amount of air bleed. As more air is allowed to bleed, less vacuum can be applied to the EGR valve, resulting in less EGR. The ECM diagnoses the system using an internal EGR test procedure.

The ECM control, of the EGR, is based on the following inputs:

^ Engine coolant temperature.
^ TPS - "OFF" idle.
^ MAP.
^ BARO.
^ TCC.
^ Engine rpm.

If Code 24 is stored, use that chart first. DTC 24

Code 32, DTC 32 will detect a faulty solenoid, vacuum supply, EGR valve or plugged passage. This chart checks for plugged EGR passages, a sticking EGR valve, or a stuck open or inoperative solenoid.

EGR Diagnostic Chart:

Test Description
Number(s) below refer to circled number(s) on the diagnostic chart.

1. With the ignition "ON," engine stopped, the solenoid should not be energized and vacuum should not pass to the EGR valve.

2. Grounding the diagnostic terminal will energize the solenoid and allow vacuum to pass to valve.

3. Checks for plugged EGR passages. If passages are plugged, the engine may have severe detonation on acceleration.

^ Vehicle speed must be greater than 2 mph for California vehicles.