Hot Engine
- Disconnect vacuum hose from EGR valve and connect vacuum gauge to hose. Push a voltmeter positive probe into the terminal at the control box connector (Yellow/White wire). Connect the negative probe to ground.
- Start and warm up engine (cooling fan must come on). Test EGR system under the following engine operating conditions. Check vacuum and voltage specifications.
EGR SYSTEM TEST
| Engine Condition |
EGR Valve Vacuum |
Yellow/White Wire Voltage |
| 1 Idle |
None |
Yes |
| 2 Hard Acceleration |
2-6 in. Hg |
None |
| 3 4500 RPM |
2-6 in. Hg |
None |
| 4 Deceleration |
None |
Yes |
- If there is vacuum available in condition 1 or no vacuum available for condition 2 and 3, check vacuum hose routing. If there are no defects, replace the EGR control valves A and B.
- If there is no voltage for condition 1 or 4, or there is voltage for condition 2 or 3, go to Trouble Shooting. If vacuum is available for condition 4, replace the EGR solenoid valve A. Retest system.