Cold Engine
NOTE. Engine coolant temperature must be below 50°C (122°F).1. Disconnect vacuum hose # 16 from the EGR valve and connect a vacuum gauge to the hose.
2. Start the engine and raise the engine speed to 4,500-5,000 rpm. Vacuum should not be available.
3. If vacuum is not available, go to hot engine inspection.
4. If vacuum is available, check for voltage at EGR control solenoid valve A (Box # 1, yellow/white). There should be voltage.
^ If there is voltage, replace EGR control solenoid valve A (Box # 1) and re-test.
^ If there is no voltage, inspect Thermosensor, inspect vacuum switch C.
5. Check for voltage at control unit connector (black/yellow wire) with ignition switch on. There should be voltage.
^ If there is no voltage, check wiring.
6. Check brown/black wire for continuity between control unit and a suitable ground. It should have continuity.