Symptom:
*CHECKING THE EGR SYSTEM
POSSIBLE CAUSES
ASD RELAY OUTPUT CIRCUIT OPEN
EGR VALVE
GROUND CIRCUIT OPEN
VACUUM SUPPLY HOSE
TEST
ACTION
APPLICABILITY
1
Disconnect the Vacuum Supply Hose at the EGR solenoid.
Connect a vacuum gauge to the Vacuum Supply Hose.
Start the engine and allow the engine to idle.
Is the vacuum above 10 inches of mercury at idle?
All
Yes
→
Go To
2
No
→
Repair leaking or restricted Vacuum Supply Hose or faulty
Vacuum Supply Pump.
Perform ROAD TEST VERIFICATION - VER-2.
2
Turn the ignition off.
Disconnect the EGR Solenoid harness connector.
Turn the ignition on.
Using a 12-volt test light connected to ground, check the ASD Relay Output circuit at
the EGR Solenoid harness connector.
Is the test light on?
All
Yes
→
Go To
3
No
→
Repair the ASD Relay Output circuit for an open.
Perform ROAD TEST VERIFICATION - VER-2.
3
Turn the ignition off.
Disconnect the EGR Solenoid harness connector.
Using a 12-volt test light connected to 12-volts, check the Ground circuit in the EGR
Solenoid harness connector.
Is the test light on?
All
Yes
→
Go To
4
No
→
Repair the Ground circuit for an open.
Perform ROAD TEST VERIFICATION - VER-2.
4
NOTE: The Vacuum Output Hose must not be leaking or restricted for the
result of this test to be valid.
Turn the ignition off.
Disconnect the Vacuum Supply and Vacuum Output Hoses in the EGR Solenoid
vacuum connector.
Connect the Vacuum Supply Hose to the Vacuum Output Hose.
Test drive the vehicle and observe vehicle performance.
Is there a power reduction on vehicle acceleration?
All
Yes
→
Test Complete.
No
→
Replace the EGR Valve.
Perform ROAD TEST VERIFICATION - VER-2.
176
DRIVEABILITY - DIESEL