Part 3 of 3

DTC 32 Chart Part 3 Of 3:

Wiring Diagram:

MAP With Key On Engine Off:

CIRCUIT DESCRIPTION:

The ECM operates a solenoid valve to control the Exhaust Gas Recirculation (EGR) valve. This solenoid valve is normally closed. By providing a ground path, the ECM energizes the solenoid valve which then allows vacuum to pass to the EGR valve.

The ECM monitors EGR effectiveness by de-energizing the EGR control solenoid valve, thereby, shutting "OFF" vacuum to the EGR valve diaphragm. With the EGR valve closed, manifold vacuum will be greater than it was during normal EGR operation and this change will be relayed to the ECM by the MAP sensor. If the vacuum change is not within the calibrated window, a DTC 32 will be set.

The ECM will check EGR operation when:

^ Vehicle speed is above 80 km/h (50 mph).
^ MAP is as listed in table (depends on altitude).
^ TP is between 9% and 20% (5.OL & 5.7L).
^ TP is between 5% and 20% (4.3L).
^ No change in Throttle Position (TP) while test is being run.



TEST DESCRIPTION: The numbers below refer to circled numbers on the diagnostic chart.


6. The remaining tests check the ability of the EGR to interact with the exhaust system. This system uses a NEGATIVE BACKPRESSURE EGR VALVE which should hold vacuum with the engine off.

7. When the engine is started, exhaust back pressure at the base of the EGR valve should open the valve's internal bleed and and vent the applied vacuum allowing the valve to seat.