Diagnostic System Check - Transmission Codes

Diagnostic Chart:

Wiring Diagram:

CIRCUIT SYSTEM DESCRIPTION
The "On-Board Diagnostic (OBD) System Check" is an organized approach to identifying a problem created by a control module system malfunction. It must be the starting point for any driveability complaint diagnosis, this will direct the service technician to the next logical step in diagnosing the complaint. Understanding the chart and using it properly will reduce diagnostic time and prevent the unnecessary replacement of good parts.

CHART SYSTEM TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. When the ignition switch is cycled to "ON," the MIL should turn "ON" briefly, then "OFF" briefly, then remain "ON" steady. This sequence will determine that the vehicle diagnostics are operational.
2. This step checks the diagnostic test, system ground, and serial data circuits.
3. Although the control module is powered up, a symptom could exist because of a system fault.
4. This step will isolate if the customer complaint is an MIL or driveability problem with no MIL. Refer to "Diagnostic Trouble Code Description" for a list of valid DTCs. An invalid DTC may be the result of a faulty scan tool, PROM or PCM. Diagnostic Trouble Code Descriptions
5. Comparison of actual control system data with the Typical Tech 1 Data Values is a quick check to determine if any parameter is not within limits. A base engine problem (i.e., advanced cam timing) may substantially alter sensor values.