Exhaust Gas Recirculation: Testing and Inspection
EGR Vacuum Regulator Solenoid Valve and Potentiometer, Checking
Observe all safety precautions: => [ Safety Precautions ] Safety Precautions
View clean working conditions: => [ Clean Working Conditions ] Clean Working Conditions
Perform a preliminary check to verify the condition: => [ Preliminary Check ] Preliminary Check.
Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.
For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.
• The EGR potentiometer G212 is part of the N18 valve assembly and is serviced as one component.
Special tools, testers and auxiliary items required
• Multimeter
• Electrical connector test lead set
Test conditions
• Fuse OK
• Battery voltage 12.5 V
• Ignition switched off
Start diagnosis
- Disconnect the EGR Vacuum Regulator Solenoid Valve/Potentiometer (N18/G212) electrical harness connector.
Checking internal resistance
- Using a multimeter, check the EGR Vacuum Regulator Solenoid Valve/Potentiometer (N18/G212) terminals 2 to 6 for resistance.
Specified value: 12.5 ohms (+/- 2.3 ohms).
- Using a multimeter, check the EGR Vacuum Regulator Solenoid Valve/Potentiometer (N18/G212) terminals 1 to 5 for resistance.
Specified value: 182.6 ohms (+/- 40 ohms).
- Reinstall the EGR Vacuum Regulator Solenoid Valve/Potentiometer (N18/G212) connector.
If any of the specified values are Not obtained:
- Replace the EGR Vacuum Regulator Solenoid Valve/Potentiometer (N18/G212).
If the specifications were obtained:
Checking voltage
• The EGR connector MUST be connected BEFORE the key turned ON. Switch the ignition ON, then disconnect the EGR connector. Failure to do this will shut off the ECM drivers and the voltage readings will be in error, leading to misdiagnosis.
- Switch the ignition ON.
- Disconnect the EGR Vacuum Regulator Solenoid Valve/Potentiometer (N18/G212) connector
- Using a multimeter, check the EGR Vacuum Regulator Solenoid Valve/Potentiometer (N18/G212) electrical harness connector terminal 2 to Ground for voltage.
- Using a multimeter, check the EGR Vacuum Regulator Solenoid Valve/Potentiometer (N18/G212) electrical harness connector terminal 6 to Ground for voltage.
- Using a multimeter, check the EGR Vacuum Regulator Solenoid Valve/Potentiometer (N18/G212) electrical harness connector terminal 3 to Battery Positive (+) for voltage.
Specified value for above tests: near Battery voltage.
- Using a multimeter, check the EGR Vacuum Regulator Solenoid Valve/Potentiometer (N18/G212) electrical harness connector terminal 1 to Ground for voltage.
Specified value: Near 5.01 V
If any of the specified values were Not obtained:
- Check the EGR Vacuum Regulator Solenoid Valve/Potentiometer (N18/G212) electrical harness to the Motronic Engine Control Module (ECM) (J623) for an for an open circuit or a short circuit.
- Check the wiring connections for damage, corrosion, loose or broken terminals.
- If necessary, repair the faulty wiring connection.
If the specified value was obtained:
Checking wiring
If the manufacturers test box is being used, perform the following step.
- Install the test box.
If the manufacturers test box is not being used, perform the following step.
- Remove the Motronic Engine Control Module (ECM) (J623). Refer to the Repair Manual.
- Using a multimeter, check the EGR Vacuum Regulator Solenoid Valve/Potentiometer (N18/G212) electrical harness connector terminal to the Motronic Engine Control Module (ECM) (J623) electrical harness connector T60 terminal for resistance.
Specified value: 1.5 ohms Max.
If the specification was not obtained:
- Check the wiring for high resistance, a short circuit to each other, Battery or Ground.
- If necessary, repair the faulty wiring connection.
- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
If no malfunction is detected in the wiring and the voltage was Not OK:
- Replace the Motronic Engine Control Module (ECM) (J623). Refer to the Repair Manual.
Final procedures
After the repair work, the following work steps must be performed in the following sequence:
1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Scan Tool Testing and Procedures.
2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Scan Tool Testing and Procedures.
3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.