Circuit Diagnosis - Fuel Injector

Electrical Diagram:

CIRCUIT DESCRIPTION

The PCM will enable an injector on the intake stroke of each cylinder. Individual cylinder fuel control is referred to as Sequential Multiport Fuel Injection (SFI).

Ignition voltage is supplied directly to the fuel injectors. The PCM 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.

DIAGNOSTIC AIDS

^ If an injector is disconnected while the engine is operating the injector driver will be disabled for the entire ignition cycle.

^ When the injector driver is disabled, an engine misfire will be apparent and a misfire DTC will set.

For intermittents, refer to Symptoms.

TEST DESCRIPTION

Number(s) below refer to step numbers on the diagnostic table.

2. Determines if a malfunction is present. For any test that requires probing the PCM or a component harness connector, must use the Connector Test Adapter kit J 35616-A. Using this kit will prevent damage to the harness connector terminals.

3. There are two ways to isolate a malfunctioning injector circuit:

^ DTC P0300 indicates a misfire is present. So use misfire current counters to locate the cylinder that is misfiring.

^ If no misfire DTC is present, Start and idle the engine while monitoring misfire current counters. If a misfire is present, the misfire current counters will increase for a cylinder that has a misfire.

6. Check injector connections before replacing the injector. A faulty connection will cause an inoperative injector.

9. Checks for an ignition feed circuit that is shorted to ground.

NOTE: Disconnecting the PCM will allow using the DVM (J 39200) to check continuity of the circuits. This will aid in locating an open or shorted circuit.