Reading and Clearing Diagnostic Trouble Codes

ALDL Connector:

On-Board Diagnostics Display Panel:

On-Board Diagnostics Chart:

DESCRIPTION:

The Electronic Climate Control (ECC) head has the ability to display ECM trouble codes. Checking the operation of the "SERVICE ENGINE SOON" ("CHECK ENGINE") light or for a code 12 may be accomplished by grounding the ALDL terminal (A to B).


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

1. Enter the diagnostics by simultaneously pressing the ECC display panel OFF and WARMER buttons until all displays are lit.
2. Malfunction codes are displayed in the following sequence:
a. ECC Current codes (Parameter Number-00)
b. ECC History codes (Parameter Number-00)
c. ECM codes (Parameter Number-01)
3. To select a specific diagnostic parameter, press HI to increment the number, and LO to decrement the number.
4. Clearing codes returns to parameter number display.
5. OUTSIDE TEMP toggles display between parameter number and parameter data.

NOTE: To exit the diagnostics test, press AUTO.