Part 3 of 3

Chart A-3:

Ignition Circuit:

CIRCUIT DESCRIPTION:
Ignition voltage is supplied to the fuel injectors on CKT 439. The paired injectors will be pulsed (turned "ON" and "OFF") when the ECM opens and grounds injector drive CKTs 467 and 468.

TEST DESCRIPTION: The numbers below refer to circled numbers on the diagnostic chart.

1. This test checks for ignition voltage at the injector jumper harness connector.

2. Checks for open in CKT 467 or CKT 468 from ECM to injectors. The test light has a path to voltage through the injector windings to ignition CKT 439.

3. Checks for short to voltage on CKT 467 or CKT 468 from ECM to injectors. Be sure all injectors are disconnected from injector harness connectors.

4. Damage to ECM injector driver may occur if either injector driver CKT 467 or CKT 468 shorts to ignition CKT 439.