Scan Tool Testing and Procedures

Diagnostic Chart:

Schematic:

CIRCUIT DESCRIPTION
The Class 2 serial data circuit to the Data Link Connector (DLC) allows bi-directional communication between the Powertrain Control Module (PCM)and a scan tool. If communication between the scan tool and the PCM cannot be established, the procedure in the DLC Diagnosis table should be used to diagnose the condition.

DIAGNOSTIC AIDS
Inspect the following items:
^ For the PCM to establish communication with the scan tool, system voltage must be between 9.0 and 16.0 volts. If system voltage is not within this range, refer to A Diagnostic System Check - Starting and Charging in Starting and Charging. Starting and Charging
^ Ensure that the correct application (model year, carline, VIN code) has been selected on the scan tool. If communication still cannot be established, use the scan tool on another vehicle in order to determine if the scan tool or the cables are the cause of the condition.
^ An intermittent may be caused by a poor connection, a rubbed through wire insulation, or a broken wire inside the insulation. Inspect for poor connections and a damaged harness. Inspect the PCM harness and the connectors for improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connections, and a damaged harness.

TEST DESCRIPTION
The number below refers to the step number on the diagnostic table:
11. The replacement PCM must be programmed and the Crankshaft Position System Variation Learn procedure must be performed.