Part 2 of 2

Code Chart 32:

EGR Circuit:

CIRCUIT DESCRIPTION:
The Exhaust Gas Recirculation (EGR) system is controlled by the ECM. The ECM controls the vacuum being supplied to the valve by energizing and de-energizing a solenoid. The ECM uses information from various engine sensors to determine when EGR is necessary. Once the ECM has requested EGR by grounding the solenoid circuit, the ECM will monitor engine operating conditions to determine if exhaust gas flow has entered the intake manifold. When the ECM tests for EGR operation and not change in engine operating conditions is indicated, a Code 32 will set.

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

1. The remaining tests check the ability of the EGR valve to interact with the exhaust system. This system uses a negative backpressure EGR valve which should hold vacuum with the engine "OFF."

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

3. Suction from shop exhaust hoses can alter backpressure and may affect the functional check of the EGR valve.

DIAGNOSTIC AIDS:
Low fuel pressure or lean fuel injectors may cause a Code 32 to set. Related Tests, Information and Procedures If fuel pressure is normal, Chart C-2A Fuel Injector Balance Test