Circuit Description
The ECM enables an injector on the intake stroke of each cylinder. Each individual cylinder fuel control is referred to as the Sequential Multiport Fuel Injection (SFI). Switched B+ voltage is supplied directly to the fuel injectors from the Engine Control Power Relay. The ECM controls each injector by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the ECM. When the ECM is commanding a component on, the voltage of the control circuit should be low (near 0 volts). When the ECM is commanding the control circuit to a component off, the voltage potential of the circuit should be high (near battery voltage). If the fault detection circuit senses a voltage other than what is expected, this DTC will set.
The ECM will monitor the injector circuit for the following conditions:
| • | Short to ground |
| • | Short to voltage |
| • | Open circuit |
| • | An internally shorted or excessively low resistance injector |
When the ECM detects any of the above malfunctions, this DTC will set and the affected driver will be disabled. The ECM will continue to test the circuit and if the fault goes away the driver will be reactivated.
Conditions for Running the DTC
| • | The ignition voltage is between 7.5-15 volts. |
| • | The engine speed is more than 80 RPM. |
Conditions for Setting the DTC
An injector circuit fault is detected.
Action Taken When the DTC Sets
The ECM illuminates the malfunction indicator lamp (MIL) and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.
Conditions for Clearing the MIL/DTC
| • | The ECM turns OFF the MIL after three consecutive drive trips that the diagnostic runs and passes. |
| • | A History DTC clears after forty consecutive warm-up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic. |
| • | The ECM battery voltage is interrupted. |
| • | The scan tool clears the MIL/DTC. |
Diagnostic Aids
Notice: Using the J 35616-A Connector Test Adapter Kit will prevent damage to the harness connector terminals.
Use theJ 35616 connector test adapter kit for any test that requires probing the ECM harness connector or a component harness connector.
Check for the following conditions:
| • | Poor connections at the ECM or at the component--Inspect the harness connectors for any backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Engine Control Module Diagnosis for the proper procedure. |
| • | Damaged harness--Inspect the wiring harness for any damage. If the harness appears to be OK, observe the scan tool while moving the related connectors and the wiring harnesses. A change in the display may help in order to locate the fault. |
Refer to Symptoms for the Intermittents.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step is to test the control circuit for a short to voltage.
-
This step is to isolate the fault to the control circuit or the ECM.
-
At this point, the fault is isolated to the engine side of the harness. This step will determine the type of fault. The upper intake will require removal in order to complete the diagnosis.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | |||||||||
2 |
Is the test lamp illuminated? | -- | Go to Step 3 | Go to Step 11 | ||||||||
Is the test lamp illuminated? | -- | Go to Step 13 | Go to Step 4 | |||||||||
4 | Probe the control circuit for the injector (that applies to this DTC) in the harness connector (ECM side) with the J 34142-B test lamp connected to B+. Is the test lamp illuminated? | -- | Go to Step 6 | Go to Step 5 | ||||||||
5 |
Does the test lamp flash when the engine is cranking? | -- | Go to Step 8 | Go to Step 7 | ||||||||
Is the test lamp illuminated? | -- | Go to Step 12 | Go to Step 16 | |||||||||
7 |
Did you find and correct a problem? | -- | Go to Step 17 | Go to Step 15 | ||||||||
Does the test lamp illuminate? | -- | Go to Step 9 | Go to Step 10 | |||||||||
9 | Test the control circuit for the injector (that applies to this DTC) from the injector harness connector to the injector main harness connector for a short to voltage. Did you find a problem? | -- | Go to Step 13 | Go to Step 14 | ||||||||
10 | Check for the following conditions:
Did you find and correct a problem? | -- | Go to Step 17 | Go to Step 14 | ||||||||
11 | Repair the open in the switched B+ voltage circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 17 | -- | ||||||||
12 | Repair the injector control circuit shorted to ground. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 17 | -- | ||||||||
13 | Repair the injector control circuit shorted to voltage. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 17 | -- | ||||||||
14 | Replace the fuel injector. Refer to Fuel Injector and Fuel Rail Replacement . Is the action complete? | -- | Go to Step 17 | -- | ||||||||
15 | Check for a poor connection or poor terminal tension at the ECM harness connector. Refer to Wiring Repairs in Wiring Systems. Also, refer to Checking Terminal Contact in Engine Control Module Diagnosis Did you find and correct a problem? | -- | Go to Step 17 | Go to Step 16 | ||||||||
16 |
Important:
Replace the ECM. Refer to Engine Control Module Replacement/Programming . Is the action complete? | -- | Go to Step 17 | -- | ||||||||
17 |
Does the scan tool indicate the diagnostic Passed? | -- | Go to Step 18 | Go to Step 2 | ||||||||
18 | Does the scan tool display any additional undiagnosed DTCs? | -- | Go to the applicable DTC table | System OK |
