Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the EGR valve.
- Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal 2 or B and ground.
- If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
- Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal 5 or E and ground.
- If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 4 or D and ground.
- If less than the specified range, test the 5-volt reference circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the ECM.
- If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Ignition OFF, verify a test lamp does not illuminate between the control circuit terminal 1 or A and 12 volts.
- If test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
- Ignition ON, command the EGR valve to 100 percent with a scan tool. The test lamp should illuminate.
- If test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
- Ignition ON, verify the scan tool EGR position sensor parameter is less than 3 percent.
- If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Install a 3A fused jumper wire between the signal circuit terminal 3 or C and the 5-volt reference circuit terminal 4 or D. Verify the scan tool EGR position sensor parameter is greater than 95 percent.
- If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
- If all circuits test normal, test or replace the EGR valve.
IMPORTANT:
The scan tool EGR Position Sensor parameter will display less than 100 percent when the EGR is commanded to 100 percent.