Without Scan Tool

Data Link Connector And Junction Block:

Duty Check DLC:

DIAGNOSTIC CONNECTORS
The provisions for communicating with the Engine Control Module (ECM) without a scan tool are the DIAG SW connector in the junction block and the diagnostic request terminal in the Duty Check Data Link Connector (DLC). Both connectors are show in the accompanying images.

CONNECTOR LOCATIONS
The junction block containing the DIAG SW connector is located under the instrument panel to the left of the steering column.

The Duty Check DLC is located in the left rear engine compartment near the strut tower.

READING DIAGNOSTIC TROUBLE CODES
Diagnostic Trouble Codes (DTCs) stored in ECM memory can be read by counting the flashes of the Malfunction Indicator Lamp (MIL) (or a test light) after grounding either the DIAG SW connector in the junction block or the diagnostic request terminal in the Duty Check DLC. When either terminal is grounded, the ECM enters its diagnostic mode and outputs DTCs to either the MIL or, if a test light is used, to the diagnostic output terminal of the Duty Check DLC.

GROUNDING CONNECTORS
DIAG SW Connector
To ground the DIAG SW connector in the junction block, simply remove the spare fuse from the junction block and insert it into the DIAG SW connector. Then, turn the ignition switch to "ON" and observe the MIL.

Diagnostic Request Terminal
To ground the diagnostic request terminal in the Duty Check DLC, connect a jumper between Duty Check DLC cavities "2" and "4."

INTERPRETING MIL OUTPUT
After grounding either the DIAG SW connector of the diagnostic request terminal, the MIL should flash DTC 12 continuously. This would be the following flash sequence: "flash, pause, flash-flash, long pause, flash, pause, flash-flash, long pause, flash, pause, flash-flash," etc. DTC 12 indicates that the ECM's diagnostic system is operating. If DTC 12 is not indicated, a malfunction is present within the diagnostic system itself, which should be addressed by consulting Powertrain Management / Diagrams / Electrical / Wiring Diagrams.

MALFUNCTION PRESENT
If any DTCs exist indicating a malfunction (DTCs other than DTC 12), those DTCs will flash instead of a DTC 12. If more than one DTC is stored in the ECM's memory, the DTCs will be repeatedly output from the lowest to the highest, with each DTC being displayed three times.