DTC P0400: EGR Function
- Check Power Supply - Turn ignition off. Turn ignition on. Measure voltage between EGR temperature sensor connector terminal No. 1 and ground. Voltage should be less than 4.5 volts. Measure voltage between ECM connector terminal No. 25 and 59. Voltage should be less than 2.1 volts. If voltage is as specified, go to next step. If voltage is not as specified, repair harness as necessary.
- Check Input Signal - Turn ignition off. Measure voltage between EGR temperature sensor connector terminal No. 2 and ECM connector terminal No. 43. If continuity is present, go to next step. If continuity is not as present, repair harness or connectors as necessary.
- Check Vacuum Source To EGR Valve - Start engine and bring to operating temperature. With engine speed at 2000-4000 RPM, disconnect vacuum hose to EGR valve. If vacuum is not present, go to next step. If vacuum is present, inspect EGR valve. See SYSTEM/COMPONENT TESTS article. Service or replace components if necessary and perform FINAL CHECK.
- Check EGR Temperature Sensor
- Disconnect EGR temperature sensor harness connector. See Fig 1. Measure resistance of EGR temperature sensor. See EGR TEMPERATURE SENSOR RESISTANCE table. If EGR temperature sensor is okay, go to next step. Repair or replace if necessary and perform FINAL CHECK.EGR TEMPERATURE SENSOR RESISTANCE
Temperature - °F (°C) Volts Ohms 32 (0) 4.81 7.9-9.7 122 (50) 2.82 0.57-0.70 212 (100) 0.8 0.08-0.10 (1) Megohms are given. - Check EGRC Solenoid - Remove EGRC solenoid valve. Apply fused battery voltage to terminals No. 1 and 2. See Fig 2. With battery voltage applied, air should pass between port "A" and "B". Air should not pass between port "A" and "C". With no voltage applied, air should pass between port "A" and "C". Air should not pass between port "A" and "B". Replace EGRC solenoid valve if not as specified. If solenoid valve is okay, Check ECM connector and terminals for corrosion or damage.