P0404
P0404-EGR POSITION SENSOR RATIONALITY OPENP0404-EGR Position Sensor Rationality Open:
Theory of Operation
The EGR valve has a position sensor and the EGR position rationality is designed to make sure that the valve moves freely within its operating range. Closed valve position reference check verifies that the valve is within its allowable upper and lower limits. The EGR position rationality test looks for a sustained error relative to commanded valve position.
WHEN MONITORED
Engine running.
SET CONDITION
The EGR flow or valve movement is not what is expected. A rationality error has been detected fro the EGR Close Position Performance. Two trip fault.
POSSIBLE CAUSES
- (K34) EGR sensor signal circuit open
- (K34) EGR sensor signal circuit shorted to voltage
- (K35) EGR solenoid control circuit shorted to voltage
- (K900) Sensor ground circuit open
- EGR solenoid assembly
- PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. ACTIVE DTC
Ignition on, engine not running.
With a scan tool, read DTCs.
Q: Is the DTC active at this time?
YES: Go To 2
NO: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Component Tests and General Diagnostics
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
2. EGR SOLENOID ASSEMBLY
Ignition on, engine not running.
With the scan tool, actuate the EGR Solenoid.
Allow the EGR Solenoid to actuate for at least 15 seconds.
Feel the EGR Solenoid for operation.
Stop actuation.
Q: Does EGR Solenoid operate while actuating and then turn off when actuation test is stopped?
YES: Go To 3
NO: Replace the EGR Solenoid Assembly. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
3. (K34) EGR SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE
Turn the ignition off.
Disconnect the EGR Solenoid harness connector.
Disconnect the C2 PCM harness connector.
Ignition on, engine not running.
Measure the voltage of the (K34) EGR Sensor Signal circuit in the EGR Solenoid harness connector.
Q: Is the voltage above 1.0 volt?
YES: Repair the short to voltage in the (K34) EGR Sensor Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 4
4. (K35) EGR SOLENOID CONTROL CIRCUIT SHORTED TO VOLTAGE
Measure the voltage on the (K35) EGR Solenoid Control circuit at the EGR Solenoid harness connector.
Q: Is the voltage above 1.0 volt?
YES: Repair the short to voltage in the (K35) EGR Solenoid Control circuit.
NO: Go To 5
5. (K900) SENSOR GROUND CIRCUIT OPEN
Turn the ignition off.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.
Measure the resistance of the (K900) Sensor ground circuit from the EGR Solenoid harness connector to the appropriate terminal of special tool #8815.
Q: Is the resistance below 5.0 ohms?
YES: Go To 6
NO: Repair the open in the (K900) Sensor ground circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
6. (K34) EGR SENSOR SIGNAL CIRCUIT OPEN
Measure the resistance of the (K34) EGR Sensor Signal circuit from the EGR Solenoid harness connector to the appropriate terminal of special tool #8815.
Q: Is the resistance below 5.0 ohms?
YES: Go To 7
NO: Repair the open in the (K34) EGR Sensor Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
7. PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Q: Were there any problems found?
YES: Repair as necessary. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Replace and program the Powertrain Control Module. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test