Circuit Test D1 - EGR On/Off Control & EGR Control (EGRC)

Fig 1: EGR Control Circuits

NOTE: Enter this test only when a Code 28 is displayed during the QUICK TEST procedure or when directed here from another CIRCUIT TEST. To prevent replacement of good components, be aware that the following non-EEC areas may be faulty: air or vacuum leaks, restricted EGR flow or EGR valve. This test is intended to diagnose only the following: harness circuits, ECA, or EGR solenoid.

1. Checking System Integrity  - Visually check all wiring, harnesses, connectors and components for evidence of damage, overheating, shorting or looseness. If a fault is found, repair as necessary. If no faults are found, go to next step.
2. Checking Voltage At ECA  - Install breakout box. Disconnect ECA. Set VOM on 20-volt scale. On turbo models, test with KOEO. On non-turbo models, test with KOER (engine above 1500 RPM). Measure voltage between test pins No. 33 and 20 (ground). If voltage is less than 10 volts, go to next step. If not, go to step 6).
3. Checking Voltage From EGR Solenoid  - On turbo models, test with KOEO. On non-turbo models, test with KOER (engine above 1500 RPM). Disconnect ECA. Leave EGR solenoid connected. Set VOM on 20-volt scale. DO NOT  pierce wires during testing. Measure voltage at "W/BL" wire terminal between EGR solenoid connector and ground. If voltage reading is less than 10 volts, go to next step. If voltage is not to specification, repair "W/BL" wire between ECA and EGR solenoid.
4. Checking Voltage To EGR Solenoid  - With KOEO and ECA disconnected, set VOM on 20-volt scale. Measure voltage at "R/BK" wire between EGR solenoid and ground. If voltage reading is less than 10 volts, go to next step. If voltage is not as specified, replace EGR solenoid.
5. Checking Voltage From Power Relay No. 2  - With KOEO, set VOM on 20-volt scale. Leave power relay disconnected. DO NOT  pierce wires during testing. Measure voltage at "R/BK" wire between power relay No. 2 and ground. If voltage reading is 10 volts or less, go to CIRCUIT TEST B1  , step 1). If voltage is not as specified, repair "R/BK" wire between EGR solenoid and power relay No. 2.
6. Checking EGR Circuit For Short To VPWR  - Install breakout box. Leave ECA disconnected. Disconnect EGR solenoid at connector. Set VOM on 20-volt scale. With KOEO, measure voltage between test pins No. 33 and 20 (ground). If voltage is greater than zero, repair short to VPWR. If voltage is zero, replace ECA.