Chart C7 - EGR Diagnosis: Notes

Before entering diagnostic chart check 10-amp ECS fuse No. 5 of fuse block. Measure EGR resistance. Resistance should be 20-100 ohms. The DFI system use a positive backpressure type EGR valve which limits EGR flow with a low exhaust backpressure. Ensure that exhaust tubes which decrease backpressure (pull air through) are NOT hooked to vehicle when diagnosing EGR system.

1. Connect vacuum gauge to source side of EGR solenoid. Start engine and check for manifold vacuum. If manifold vacuum is not indicated, repair leaks or obstruction between the EGR solenoid and throttle body.
2. Connect vacuum gauge to EGR valve vacuum supply. There should be no vacuum with engine running. If there is, follow diagnostic chart.
3. With vacuum gauge connected to EGR valve vacuum supply, unplug the EGR solenoid connector. There should be more than 8 in. Hg of vacuum available. if not, repair leak or obstruction in EGR valve vacuum hose.

Fig 1: Flow Chart C7 Schematic, EGR Diagnosis

Fig 2: Flow Chart C7 (1 Of 2), EGR Diagnosis

Fig 3: Flow Chart C7, EGR Diagnosis

1. This step checks for voltage to EGR solenoid and ground signal from ECM. If either of these is missing, the EGR solenoid will command EGR to come on at all times.
2. This step checks ECM's ability to turn solenoid off. If light goes off, the electrical portion of the EGR system is okay.