DTC 63

Codes 63, 64, And 65 Chart:

Code 63,64,65 Wiring Diagram:

CIRCUIT DESCRIPTION:


Codes 63, 64, and 65 are EGR flow test failures. The ECM on a closed throttle coast down will cycle the solenoids "ON" and "OFF" individually and look for a resulting change in engine rpm and O2 sensor activity.

NOTE: Because of all the possible color code combinations used on electrical wiring diagrams, always refer to ECM CONNECTOR IDENTIFICATION under ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS for correct color code identification of circuit.

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


1. You should be able to discern a change in the engine rpm as each solenoid is cycled "ON." Solenoid #1 should have the smallest change and #3 should have the largest change and may even stall the engine.

2. Check for an open in circuit 697, 698, 699 or a faulty ECM connection.

NOTES:

If the digital EGR valve shows signs of excessive heat, a melted condition, check the exhaust system for blockage or possibly a plugged converter. Refer to CHART B-1 in EMISSIONS. A plugged exhaust may be do to a:

^ STUCK OPEN INJECTOR
^ GROUNDED DRIVER CKT
^ POSSIBLE FAULTY ECM



DIAGNOSTIC AIDS:

An intermittent may be caused by a poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check for Poor Connection or Damaged Harness Inspect ECM harness connectors for backed out terminals "BC2," "BC3," and "BD2," improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

Intermittent Test - If connections and harness check OK, connect a digital voltmeter from effected terminals to ground while moving related connectors and wiring harness. If the failure is induced, the voltage reading will change.