Reading Diagnostic Trouble Codes (DTC)s

Difficulty rating:
How often:	Only when the MIL is on
Time to allow:	10min
Tools/ materials needed:	Small flat screw driver

The stored (DTC)s are accessed using the red diode on the Engine Control Module (ECM) . The codes are interpreted by the number and duration the diode flashes.

A long flash (0.6 seconds) indicates the "tens" digit while a short flash (0.3 seconds) is the "ones" digit. All flashes will have a short pause in between.

For example, if the red diode flashes once and then flashes twice rapidly this should be interpreted as code 12 . The codes are displayed in numerical order starting with the lowest and ending with the highest.

If more than one code is in memory the ECM will always display the lowest number first, pause for about two seconds and then go the next higher number. This will continue until all the stored codes have been displayed. The ECM will then go back to the lowest numbered code and repeat the cycle.

EXTRACTING DIAGNOSTIC TROUBLE CODES

• Access the ECM and position it for observing the diode.
• Turn the ignition switch ON (do not start the engine).
• Confirm that the MALFUNCTION INDICATOR LAMP (MIL) in the instrument panel illuminates. If not, check the bulb and replace if faulty.
• Turn the diagnostic mode selector on the ECM fully clockwise for at least two seconds then turn the selector fully counterclockwise. The Electronic Concentrated Engine Control System (ECCS) is now in mode to display DTC's

How to Erase Diagnostic Test Mode
The Diagnostic trouble codes can be erase from the backup memory in the ECM by disconnecting the battery terminals for more that 24 hours.

Note:
Be careful not to erase the stored memory before starting the trouble diagnostic.