Chart A1-5 Fuel Injector Circuit Check

Chart A1-5: Fuel Injector Circuit Check:

Chart A1-5: Fuel Injector Circuit Check:

Circuit Description:
When the ignition switch is turned to the "ON" or "START" position (engine running), the engine control module (ECM) will energize/de-energize the fuel injectors solenoid coil. With this coil energized, a plunger is activated, allowing pressurized fuel to be sprayed through the fuel injectors into the combustion chamber where it is mixed with air from the intake manifold; thus creating the proper air/fuel mixture needed for combustion.

Test Description:
1. This checks to see if the ECM is controlling the ground path to the fuel injectors.

2. This checks the resistance of the fuel injectors.

3. This checks for an open or short to ground in the BLK or BLK/RED wires between the fuel injectors and the ECM, or for faulty fuel injectors or faulty ECM.

Diagnostic Aids:
There may be fuel spray at the fuel injectors, but it may not be enough to start the engine. If the fuel injectors and their circuits are OK, and fuel spray is detected, the fuel injector nozzle may be partly blocked or restricted, refer to Chart A1-7A for circuit opening relay circuit test.

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connections before component replacement