DTC 32

EGR Solenoid Valve Wiring Circuit:

Circuit Description:

The Exhaust Gas Recirculation (EGR) valve vacuum is controlled by an ECM controlled solenoid valve. The ECM will turn the EGR "ON" and "OFF" (Duty Cycle) by grounding CKT 435. The duty cycle is calculated by the ECM based on information from the engine coolant temperature, air flow and engine RPM. There should be no EGR when in park or neutral, TP sensor input below a specified value, or TP sensor indicating Wide Open Throttle (WOT).

With the ignition "ON" engine stopped, the EGR solenoid valve is de-energized and by grounding the diagnostic "test" terminal, the solenoid valve is energized.

PART 1 OF 2

DTC 32 - Exhaust Gas Recirculation (EGR) Circuit (Page 1 Of 2):

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

1. Intake Passage: Shut "OFF" engine and remove the EGR valve from the manifold. Plug the exhaust side hole with a suitable stopper. With the intake side hole open, attempt to start the engine. If the engine runs at a very high idle (up to 3000 RPM is possible) or starts and stalls, the EGR passages are not restricted. If the engine starts and idles normally, the EGR intake side passage in the intake manifold is restricted.
Exhaust Passage: With EGR valve still removed, plug the intake side hole with a suitable stopper. With the exhaust side hole open, check for the presence of exhaust gas. If no exhaust gas is present, the EGR exhaust side passage in the intake manifold is restricted.
2. By grounding the diagnostic "test" terminal, the EGR solenoid valve should be energized and allow vacuum to be applied to the gage. The vacuum at the gage may or may not slowly bleed off. It is important that the gage is able to read the amount of vacuum being applied.
3. When the diagnostic "test" terminal is grounded, the vacuum gage should bleed off through a vent in the solenoid valve. The pump gage may or may not bleed off but this does not indicate a problem.
4. This test will determine if the electrical control part of the system is at fault or if the connector or solenoid valve is at fault.

Diagnostic Aids:

Suction from shop exhaust hoses can alter backpressure and may affect the operation of the EGR valve during install testing.

PART 2 OF 2

DTC 32 - Exhaust Gas Recirculation (EGR) Circuit (Page 2 Of 2):

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

1. The remaining test checks 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 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.

Diagnostic Aids:

The EGR circuit can be inoperative if the Park/Neutral Position (PNP) switch is misadjusted or faulty. The EGR is disabled when in park or neutral. To check the PNP switch, Chart C-1A Park/Neutral Switch Diagnosis
During normal EGR valve operation, the movement of the EGR valve pintle is small. It is important to determine whether or not the valve pintle moves and not how much it moves.
Suction from shop exhaust hoses can alter backpressure and may affect the functional check of the EGR valve.