Sierra 3500 4WD V8-6.0L (2008)
3. Ignition OFF, verify that a test lamp does not illuminate between the powertrain relay coil B+ circuit and the control circuit.
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If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
4. Remove the test lamp.
5. Command the powertrain relay ON, with a scan tool. Verify with a scan tool that the powertrain relay Ckt. Short Volts Test Status parameter is
OK.
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If not the specified value, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
6. Test the coil side of the powertrain relay for 65-110 ohms.
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If not within the specified value, replace the relay.
7. Ignition OFF, disconnect the ECM C1 connector.
8. Test the powertrain relay control circuit for an open/high resistance.
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If the circuit tests normal, replace the ECM.
9. Verify that a test lamp does not illuminate between the relay ignition 1 voltage circuit and ground.
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If the test lamp illuminates, test the relay ignition 1 voltage circuit for a short to voltage. If the circuit tests normal, replace the ECM.
10. Verify that a test lamp illuminates between the relay switch B+ and ground.
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If the test lamp does not illuminate, test the relay switch B+ circuit for a short to ground, or an open/high resistance. If the circuits test normal,
and the fuse for the ignition 1 voltage circuit is open, test the ignition 1 voltage circuit to the ECM for a short to ground. If the circuit tests
normal, replace the ECM.
11. Connect a 20 A fused jumper wire between the relay switch B+ and the relay ignition 1 voltage circuit.
12. Ignition ON, engine OFF, monitor the EC Ignition Relay Feedback parameter with a scan tool. The parameter should display B+.
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If the parameter does not display B+, test the ignition 1 voltage circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
13. If all circuits test normal, replace the relay.
Repair Instructions
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Relay Replacement (Attached to Wire Harness) Relay Replacement (Within an Electrical Center)
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Engine Control Module Replacement
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Engine Control Module Programming and Setup (W/RPO LMM) Engine Control Module Programming and Setup (GAS)
Repair Verification
1. Install any components that have been removed or replaced during diagnosis.
2. Perform any adjustment, programming, or setup procedures that are required when a component or module is removed or replaced.
3. Clear the DTCs.
4. Turn OFF the ignition for 60 seconds.
5. Ignition ON, command the powertrain relay ON and OFF with a scan tool, while observing the powertrain relay circuit status parameters, The
circuit status parameters should change from OK to Not Run or Not Run to OK.
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If another DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure. See:
Powertrain Management/Computers and Control Systems/Testing and Inspection/Diagnostic Trouble Code Descriptions
