Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC P1476: Exhaust Gas Recirculation (EGR) Solenoid Control Circuit Short to VoltageDTC P1477: Exhaust Gas Recirculation (EGR) Solenoid Control Circuit Short to Ground
DTC P1478: Exhaust Gas Recirculation (EGR) Solenoid Control Circuit Open
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Ignition 1 Voltage | P1478 | P1478 | -- | -- |
Exhaust Gas Recirculation (EGR) Control Circuit | P1477 | P1478 | P1476 | -- |
Circuit/System Description
Voltage is provided to the exhaust gas recirculation (EGR) solenoid by the ignition 1 voltage circuit through a fuse. Ground is provided to the EGR valve on the control circuit by a low side driver within the engine control module (ECM). The ECM energizes the solenoid which allows vacuum to pass to the EGR valve. The ECM monitors the voltage on the control circuit of the EGR valve to determine if a failure is present.
Conditions for Running the DTC
| • | The ignition is ON or the engine is operating. |
| • | The DTCs runs continuously once the above conditions are met. |
Conditions for Setting the DTC
P1476
The ECM detects a short to voltage on the EGR solenoid control circuit.
P1477
The ECM detects a short to ground on the EGR solenoid control circuit.
P1478
The ECM detects an open on the EGR solenoid control circuit.
Action Taken When the DTC Sets
DTCs P1476, P1477, and P1478 are Type C DTCs.
Conditions for Clearing the DTC
DTCs P1476, P1477, and P1478 are Type C DTCs.
Reference Information
Schematic Reference
Description and Operation
Exhaust Gas Recirculation (EGR) System Description
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, command the EGR solenoid ON with a scan tool. You should hear an audible click for about 3-5 seconds.
- Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the EGR solenoid.
- Ignition ON, test for battery voltage between the ignition 1 voltage circuit terminal 5 and ground.
- Ignition OFF, connect a test lamp between the control circuit terminal 1 and the ignition 1 voltage circuit terminal 5.
- Ignition ON, command the EGR solenoid ON and OFF with a scan tool. The test lamp should turn ON and OFF.
- If all circuits test normal, test or replace the EGR solenoid.
| ⇒ | If less than B+, repair the ignition 1 voltage circuit for a short to ground or an open/high resistance. |
| ⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM. |
| ⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
Component Testing
- Test for 24-28 ohms of resistance between the ignition 1 voltage terminal 5 and the control circuit terminal 1.
- Test for infinite resistance between each terminal and the EGR solenoid housing.
| ⇒ | If not within the specified range, replace the EGR solenoid. |
| ⇒ | If not the specified value, replace the EGR solenoid. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for engine control module replacement, setup, and programming |
