Diagnostics

Diagnostics

Special Tool(s):

Diagnosing electronically controlled automatic transmissions is simplified using the following procedures. It is important to remember that there is a definite procedure to follow. Do not take shortcuts or assume that critical checks or adjustments have already been made. Follow the procedures as written to avoid missing critical components or steps. By following the diagnostic sequence, the technician will be able to diagnose and repair the concern the first time.

On-Board Diagnostic (OBD) With Scan Tool

NOTE: For detailed instruction and other diagnostic methods using the scan tool or equivalent, refer to the scan tool tester manual and Computers and Control Systems.

These Quick Tests should be used to diagnose the powertrain control module (PCM) and should be carried out in order.
^ Quick Test 1.0 - Visual Inspection
^ Quick Test 2.0 - Set Up
^ Quick Test 3.0 - Key On, Engine Off (KOEO)
^ Quick Test 4.0 - Continuous Memory Codes
^ Quick Test 5.0 - Key On, Engine Running (KOER)
^ Special Test Modes
- Wiggle Test Mode
- Output Test Mode
^ PCM Reset Mode
^ Clearing DTCs P1000
^ On-Board Diagnostic (OBD) II Drive Cycle
^ Other Diagnostic Tool Features

For other diagnostic testing features using the scan tool, refer to Computers and Control Systems.

After the On-Board Diagnostics
If DTCs appear while carrying out the on-board diagnostics, refer to Diagnostic Trouble Code (DTC) Charts for information on condition and symptoms.
This chart will be helpful in referring to the correct procedure(s) and to aid in diagnosing internal transmission concerns and external non-transmission inputs. Prior to entering pinpoint tests, refer to any TSBs for transmission concerns.

Being with non-transmission related DTCs, and then service any transmission related DTCs. The pinpoint tests are used in diagnosing electrical concerns of the transmission. Make sure that the vehicle wiring harnesses, the powertrain control module (PCM), engine control module (ECM), DEM module and other modules are diagnosed as well.