For 1990-2009 cars
Engine Controls Components
Fuel Injectors
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The engine control module (ECM) enables an injector on the intake stroke of each cylinder. Each individual cylinder fuel control is referred to as 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 diagnostic trouble code (DTC) will set.

The ECM will monitor the injector circuit for the following:

• | 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 battery voltage is between 7.5-15 volts.

• | The engine speed is more than 40 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 scan tool clears the MIL/DTC.

### Diagnostic Aids

Use the J 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 a poor terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems for the proper procedure.

• | Damaged harness--Inspect the wiring harness for 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 locate the fault.

Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems for the Intermittents.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This step is to test the control circuit for a short to voltage.

2. This step is to isolate the fault to the control circuit or the ECM.

3. 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 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Turn OFF the ignition.
2. Disconnect the main injector connector.
3. Turn ON the ignition, leaving the engine OFF.
4. Probe the switched B+ voltage circuit in the harness connector (ECM side) with the test lamp connected to ground.

Is the test lamp illuminated?

--

Go to Step 3

Go to Step 11

3 |

1. Turn ON the ignition, with the engine OFF.
2. Probe the control circuit for the injector (that applies to this DTC) in the harness connector (ECM side) with the test lamp connected to ground.

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 test lamp connected to B+. Is the test lamp illuminated? | -- | Go to Step 6 | Go to Step 5
5 |

1. Probe the control circuit for the injector (that applies to this DTC) in the harness connector (ECM side) with the test lamp connected to B+.
2. Crank the engine.
3. Observe the test lamp while cranking the engine.

Does the test lamp flash when the engine is cranking?

--

Go to Step 8

Go to Step 7

6 |

1. Turn OFF the ignition.
2. Disconnect the ECM.
3. Probe the control circuit for the injector (that applies to this DTC) in the harness connector (ECM side) with the test lamp connected to B+.

Is the test lamp illuminated?

--

Go to Step 12

Go to Step 16

7 |

1. Turn OFF the ignition.
2. Disconnect the ECM.
3. Test for an open or high resistance in the Injector Control circuit from the main injector harness connector to the ECM harness connector.
4. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 15

8 |

1. Turn OFF the ignition.
2. Use a jumper wire with suitable mating terminals in order to reconnect only the Switched B+ circuit in the male half of the main injector harness connector to the Switched B+ circuit in the female half of the main injector harness connector.
3. Probe the control circuit for the injector (that applies to this DTC) in the harness connector (injector side) with the test lamp connected to ground.
4. Turn ON the ignition, with the engine OFF.

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 short to voltage? | -- | Go to Step 13 | Go to Step 14
10 | Inspect/test for the following conditions:

• | Poor connections/terminal tension at the fuel injector or at the main injector connector. Refer to Testing for Intermittent Conditions and Poor Connections .

• | The injector control circuit for an open or short to ground between the injector and the main injector connector.

• | The switched B+ circuit for an open between the injector and the main injector connector.

• | Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

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 short to ground in the injector control circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 17 | --
13 | Repair the short to voltage in the injector control circuit. 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 |

1. Check for a poor connection or poor terminal tension at the ECM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
2. Repair as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 16

16 | Important:

• | Perform the Idle Learn Procedure when replacing the ECM or the throttle body.

• | This vehicle is equipped with a Theft Deterrent System which interfaces with the Engine Control Module (ECM). Program the new ECM with the frequency code of the theft deterrent module that is currently on the vehicle.

Replace the ECM. Refer to Engine Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 17

--

17 |

1. Using the scan tool, clear the DTCs.
2. Start the engine.
3. Allow the engine to idle until the engine reaches the normal operating temperature.
4. Select DTC and the Specific DTC function.
5. Enter the DTC number that was set.
6. Operate the vehicle within the Conditions for Running this DTC until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate the DTC 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