P0400
P0400 - EGR SYSTEM PERFORMANCE
When Monitored and Set Condition
- When Monitored: A constant engine speed between 900 and 1700 RPM and no other EGR or MAP sensor faults.
- Set Condition: The PCM commands the EGR valve to open. The MAP sensor value must drop by a minimum of 54 mbar (1.6 in. Hg) when EGR is commanded open or a fault is set.
Diagnostic Test
1. PRE-DIAGNOSTIC CHECK OUT
NOTE: Always perform diagnostics with a fully charged battery.
NOTE: Check connectors - Clean/repair as necessary. Poor pin to terminal connections can set DTCs.
NOTE: Check for applicable TSBs related to the problem.
Turn the ignition on.
With the DRB III(R), read PCM DTCs.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors. Repair as necessary.
Perform this procedure prior to symptom diagnosis.
Continue
- Go To 2
2. CHECK FOR CURRENT DTC
WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
NOTE: If the PCM detects and stores a DTC, the PCM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the DRB III(R) at the same time the DTC is displayed.
NOTE: Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for a DTC.
Turn the ignition on.
With the DRB III(R), erase PCM DTCs.
NOTE: It maybe necessary to road test the vehicle for this DTC to set.
With the DRB III(R), read PCM DTCs.
Did this DTC set again?
Yes
- Go To 3
No
- Go To 10
3. EGR OPERATION
Turn the ignition on.
Turn all accessories off.
Start the engine.
Allow the engine to reach normal operating temperature.
Does the engine run rough or stall?
Yes
- Go To 4
No
- Go To 5
4. EGR VALVE OPEN AT IDLE
Turn the ignition off.
Disconnect the EGR Solenoid harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Start engine. Attempt to allow the engine to idle.
Does the engine run rough or stall?
Yes
- Inspect the EGR tube assembly. If OK, replace the EGR valve.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
No
- Go To 5
5. EGR SOLENOID
NOTE: Check the Engine Control Fuse 2 in the Relay Control Module. If it is open, multiple DTCs will be set in the PCM. Determine the cause of the open fuse before continuing using the wiring diagrams/schematics as a guide.
Turn the ignition off.
Disconnect the EGR solenoid harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Connect a 12-volt test lamp between the EGR Solenoid Control circuit and the Fused Engine Control Relay Output circuit.
Turn the ignition on.
With the DRB III(R), actuate the EGR VAC TRANSDUCER.
Does the test light flash on and off?
Yes
- Replace the EGR Solenoid.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
No
- Go To 6
6. FUSED ENGINE CONTROL RELAY OUTPUT CIRCUIT OPEN
With the ignition on.
Measure the voltage of the Fused Engine Control Relay Output circuit at the EGR Solenoid harness connector.
Is the voltage above 10 volts?
Yes
- Go To 7
No
- Repair the Engine Control Relay Output circuit for an open.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
7. EGR SOLENOID CONTROL CIRCUIT SHORT TO GROUND
Turn the ignition off.
Disconnect PCM C2 harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between ground and the EGR solenoid control circuit.
Is resistance above 100 kohms?
Yes
- Go To 8
No
- Repair the EGR solenoid control circuit for a short to ground.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
8. EGR SOLENOID CONTROL CIRCUIT OPEN
With the ignition off.
Measure the resistance of the EGR Solenoid Control circuit from the EGR Solenoid harness connector to the PCM C2 harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go To 9
No
- Repair the EGR Solenoid Control circuit for an open.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
9. EGR SOLENOID CONTROL CIRCUIT SHORT TO VOLTAGE
Turn the ignition on.
Measure the voltage of the EGR Solenoid Control circuit at the EGR Solenoid connector.
Is the voltage below 1.0 volt?
Yes
- Replace and program the Powertrain Control Module.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
No
- Repair the EGR Solenoid Control circuit short to voltage.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
10. INTERMITTENT WIRING AND CONNECTORS
The condition that caused this DTC to set is currently not present. Inspect the related wiring harness for a possible intermittent condition.
NOTE: Check connectors - Clean/repair as necessary. Poor pin to terminal connections can set DTCs.
NOTE: Check for any Technical Service Bulletins that may apply.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors specific to this DTC. Wiggle the wires while checking for shorts and open circuits.
Were there any problems found?
Yes
- Repair as necessary.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
No
- The condition that caused this DTC to set is currently not present. Inspect the related wiring harness for a possible intermittent condition.