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P0203






P0203-FUEL INJECTOR 3 CIRCUIT/OPEN





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams. Electrical Diagrams

Theory of Operation

The Engine Control Module (ECM) has a common internal driver circuit to all three Fuel Injectors on each bank. If any injector circuit on a given bank has a failure, a DTC will be set for all three Fuel Injectors on that bank. Fuel Injectors 1-3 are grouped together on bank 1. Fuel Injectors 4-6 are grouped together on bank 2. If any of the Fuel Injectors or Fuel Injector circuits is shorted to power or ground, the ECM will shut down all three Fuel Injectors on that bank to protect itself from damage. This will cause all three Fuel Injector DTCs for that bank to be set simultaneously. The MIL lamp will light immediately after the diagnostic runs and fails. During this time the customer may experience lack of power, an engine surge or stumble. The MIL lamp will turn off once the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:
While the engine is running.

- Set Condition:
When the Fuel Injector current falls below a calibrated threshold.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC

NOTE: A short to power or ground on any of the Fuel Injectors, Fuel Injector High Side Driver or Injector Control circuits will cause all of the Fuel Injector DTCs to set for bank 1. The next three steps of this diagnostic test are designed to determine which Fuel Injector or Fuel Injector circuit is causing the DTCs to set. Therefore, if all three DTCs are set together, any of the bank 1 (P0201,P0202, P0203) DTCs can be used to find the root cause of the problem.

1. Ignition on, engine not running.
2. With the scan tool check for active DTCs.

Is the DTC active?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. CHECKING CONTINUITY THROUGH FUEL INJECTORS 1,2,3 (BANK 1)




1. Turn the ignition off.
2. Disconnect the ECM C1 harness connector.
3. Using an ohm meter, measure the continuity of each Fuel Injector circuit on bank 1:
- Measure between the High Side Driver circuit and the Injector Control circuit of Fuel Injector 1 at the ECM C1 harness connector.
- Measure between the High Side Driver circuit and the Injector Control circuit of Fuel Injector 2 at the ECM C1 harness connector.
- Measure between the High Side Driver circuit and the Injector Control circuit of Fuel Injector 3 at the ECM C1 harness connector.

NOTE: Be sure to zero the Ohm meter prior to checking the Fuel Injector circuit. Resistance reading should be between 0-1 Ohm.

Is the resistance between 0-1 Ohm on all circuits?

Yes

- Go To 3

No

- Go To 8

3. CHECKING FUEL INJECTORS 1,2,3 (BANK 1) CIRCUITS FOR A SHORT TO GROUND




1. Using an ohm meter, check for a short to ground on each Fuel Injector circuit on bank 1:
- Measure between ground and the High Side Driver circuit of Fuel Injector 1 at the ECM C1 harness connector.
- Measure between ground and the High Side Driver circuit of Fuel Injector 2 at the ECM C1 harness connector.
- Measure between ground and the High Side Driver circuit of Fuel Injector 3 at the ECM C1 harness connector.

NOTE: There should be no continuity between the circuit and ground.

Is the resistance less than 10k Ohms on any circuit?

Yes

- Go To 12

No

- Go To 4

4. CHECKING FUEL INJECTORS 1,2,3 (BANK 1) CIRCUITS FOR A SHORT TO VOLTAGE




1. Turn the ignition on.
2. Using a volt meter, check for a short to battery on each Fuel Injector circuit on bank 1:
- Measure between ground and the High Side Driver circuit of Fuel Injector 1 at the ECM C1 harness connector.
- Measure between ground and the High Side Driver circuit of Fuel Injector 2 at the ECM C1 harness connector.
- Measure between ground and the High Side Driver circuit of Fuel Injector 3 at the ECM C1 harness connector.

NOTE: There should be no voltage present.

Is the voltage below 1.0 Volt on all circuits?

Yes

- Go To 5

No

- Go To 6

5. CHECKING DRIVER CIRCUITS SHORTED TOGETHER




1. Turn ignition off.
2. Disconnect all bank 1 Fuel Injector wires at the Fuel Injectors.
3. Measure the resistance between all bank 1 Driver circuits at the ECM C1 harness connector.

Is the resistance below 10k Ohms between any Driver circuits?

Yes

- Repair the Driver circuits that are shorted together.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the Engine Control Module.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

6. HIGH SIDE DRIVER SHORTED TO VOLTAGE





NOTE: Perform the following tests on the Fuel Injector circuit which was faulty.

1. Disconnect Fuel Injector wires at the Fuel Injector.
2. Measure the voltage of the High Side Driver circuit at the ECM C1 harness connector.

Is the voltage below 1.0 Volt?

Yes

- Go To 7

No

- Repair the High Side Driver circuit for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

7. INJECTOR CONTROL CIRCUITS SHORTED TO VOLTAGE




1. Measure the voltage of the Injector Control circuit at the ECM C1 harness connector.

Is the voltage below 1.0 Volt?

Yes

- Test complete. Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

No

- Repair the Injector Control circuit for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

8. CHECKING VALVE COVER PASS THROUGH HARNESS CIRCUIT





NOTE: Perform the following tests on the Fuel Injector circuit which was faulty.

1. Disconnect the Valve Cover Pass Through harness connector.
2. Measure the resistance between Low Side Driver circuit and the High Side Driver circuit of the Valve Cover Pass Through connector terminals.

NOTE: Be sure to zero the Ohm meter prior to checking the Fuel Injector circuit.

Is the resistance between 0-1 Ohm?

Yes

- Go To 9

No

- Go To 11

9. CHECKING HIGH SIDE CIRCUIT IN ENGINE HARNESS




1. Measure the resistance of the High Side Driver circuit between the Valve Cover Pass Through harness connector and the ECM C1 harness connector.

NOTE: Be sure to zero the Ohm meter prior to checking the Fuel Injector circuit.

Is the resistance between 0-1 Ohm?

Yes

- Go To 10

No

- Repair the open or high resistance in the High Side Driver circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

10. CHECKING INJECTOR CONTROL CIRCUIT IN ENGINE HARNESS




1. Measure the resistance of the Injector Control circuit between the Valve Cover Pass Through harness connector and the ECM C1 harness connector.

NOTE: Be sure to zero the Ohm meter prior to checking the Fuel Injector circuit.

Is the resistance between 0-1 Ohm?

Yes

- Test complete. Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

No

- Repair the open or high resistance in the Injector Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

11. CHECKING FUEL INJECTORS
1. Disconnect all bank 1 Fuel Injector wires at the Fuel Injectors.
2. Measure the resistance across the terminals at the Fuel Injector.

NOTE: Be sure to zero the Ohm meter prior to checking the Fuel Injector circuit.

Is the resistance between 0-1 Ohm?

Yes

- Replace the Valve Cover Pass Through harness.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the Fuel Fuel Injector.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

12. CHECKING DRIVER CIRCUITS SHORTED TOGETHER




1. Disconnect all bank 1 Fuel Injector wires at the Fuel Injectors.
2. Measure the resistance between all bank 1 Driver circuits at the ECM C1 harness connector.

Is the resistance below 10k Ohms between any circuits?

Yes

- Go To 13

No

- Go To 14

13. CHECKING VALVE COVER PASS THROUGH HARNESS CIRCUIT




1. Disconnect the Valve Cover Pass Through harness connector.
2. Measure the resistance between all bank 1 Driver circuits of the Valve Cover Pass Through connector terminals.

Is the resistance below 10k Ohms between any circuits?

Yes

- Replace the Valve Cover Pass Through harness.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Repair the short between the bank 1 Driver circuits in the engine harness.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

14. CHECKING HIGH SIDE DRIVER CIRCUIT FOR A SHORT TO GROUND





NOTE: Perform the following tests on the Fuel Injector circuit which was faulty.

1. Disconnect the Valve Cover Pass Through harness connector.
2. Measure the resistance between ground and the High Side Driver circuit at the ECM C1 harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short to ground in the High Side Driver circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 15

15. CHECKING INJECTOR CONTROL CIRCUIT FOR A SHORT TO GROUND




1. Measure the resistance between ground and the Injector Control circuit at the ECM C1 harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short to ground in the Injector Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 16

16. CHECKING FUEL INJECTORS
1. Measure the resistance between ground and one of the Fuel Injector terminals.

Is the resistance below 10k Ohms?

Yes

- Replace the Fuel Injector.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the Valve Cover Pass Through harness.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

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