Diagnostic System Check

Chart I.:

PCM Wiring:

Scan Tool Hookup To ALDL Connector.:

DESCRIPTION
The diagnostic circuit check is always the starting point for any malfunction code or driveability problem. This check verifies the PCM's on board diagnostics are functioning properly. While performing a diagnostic circuit check, record codes and flags for use in diagnosing possible sub-system failures.

OPERATION
^ Key, "ON" - Engine "OFF" SES telltale should be "ON" steady.

^ When ALDL connector Pin B is grounded to Pin A with Key "ON" - Engine "OFF", diagnostic mode is entered.
^ Code 12 will flash the SES indicating diagnostic communication.
^ Code 12 will flash three times followed by any other Engine Codes (EC) that may be stored.
If code 12 is not indicated, a problem is present within the diagnostic system itself.
^ Code 11 will be displayed LAST to indicate if there are any Transmission Codes (TC) stored in memory.
^ The TC codes will flash on the "SHIFT TO D2" lamp or the "HOT" lamp.

NOTE: Do not operate the vehicle for a prolonged period of time in this mode. Damage to the Catalytic Converter may result.


DIAGNOSTIC AIDS
The following circuits are energized when the vehicle enters diagnostic mode:
^ Cooling fan is turned "ON".
^ IACV is pulsed in and out.
^ Enables transaxle actuator quick test.*
^ Hot telltale turned "ON".


* If actuators are suspected faulty, refer to the actuators quick test.