Negative Backpressure EGR Valve

Negative Backpressure EGR System Test:

EGR Circuit:

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) operates a solenoid to control the Exhaust Gas Recirculation (EGR) valve. This solenoid is normally closed. By providing a ground path, the PCM energizes the solenoid which then allows vacuum to pass to the EGR valve. The PCM control of the EGR is based on the following inputs:

- Engine Coolant Temperature - above 25°C (77°F).
- Throttle Position (TP) - "OFF" idle.
- Manifold Absolute Pressure (MAP).

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.

CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. Checks for solenoid stuck open.
2. Checks for solenoid always being energized.
3. Grounding test terminal should energize solenoid and vacuum should drop.
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.