DTC 54

Trouble Code Chart - 53, 54 & 55:

Digital EGR Assembly Wiring:

CIRCUIT DESCRIPTION
DTCs 53, 54 and 55 are EGR flow test failures. The PCM tests the medium and large EGR solenoid valves by cycling each of them "ON" momentarily while monitoring engine RPM. When a solenoid is turned "ON," the PCM expects to see a drop in engine RPM. DTC 53 is set if the expected drop is not seen 8 out of 12 times when the EGR #1 solenoid is tested. If the expected drop is not seen for the medium (EGR #2) solenoid for 6 out of 8 tests, DTC 54 is set. If the large (EGR #3) solenoid test fails 3 out of5 times, DTC 55 is set.

The PCM will run the EGR flow tests when the following conditions are met:
^ Engine coolant temperature greater than 84°C (183°F).
^ Vehicle in "Coast Down" condition (but not in "Decel Fuel Cutoff").
^ Oxygen sensor voltage greater than 566 mV.
^ Vehicle in 1st or 2nd gear.
^ Vehicle speed over 25 mph.
^ A/C clutch not commanded "ON."
^ RPM between 800 and 1000 (to run EGR #1 test).
^ RPM between 825 and 1025 (to run EGR #2 test).
^ RPM between 850 and 1050 (to run EGR #3 test).




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

1. You should be able to discern a change in engine RPM as each solenoid is cycled "ON." Solenoid #3 may cause the engine to stall when cycled "ON" at idle.

2. If the test light lights, the PCM and wiring are OK.

NOTE: If the digital EGR valve shows signs of excessive heat, check the exhaust system for blockage (possibly a plugged converter) using the procedure found on CHART B-1. If the exhaust system is restricted, repair the cause; one of which might be an injector which is open due to one of the following:
a. Stuck.
b. Grounded driver circuit.
c. Possible faulty PCM.

If this condition is found, the oil should be checked for possible fuel contamination.

DIAGNOSTIC AIDS:

^ An intermittent may be caused by a poor connection, rubbed-through wire insulation, or a wire broken inside the insulation.

^ Poor Connection or Damaged Harness - Inspect PCM harness connectors for backed out terminals "A5", "A10" and "A11", 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, monitor a digital voltmeter connected between affected terminals and ground while moving related connectors and wiring harness. If the failure is induced, the voltage reading will change.

^ Check for a restriction in EGR tube or passage. Also, ensure there is not excessive carbon buildup on EGR valve orifices.