Reading Diagnostic Trouble Codes
READING DIAGNOSTIC CODESThe Electronic Control Unit (ECU) monitors several engine sensors and actuators. If a problem occurs the information is stored in the ECU's memory for retrieval.
The codes are displayed by the green and red diodes on the ECU. When the codes are extracted they are interpreted by the number of times the diodes flash.
The red diode will flash "X" number of times, this will represent units of ten, then the green diode will flash "X" number of times, this will represent units of one.
For example, if the red diode flashes once and the green diode flashes twice this should be interpreted as code 12. The codes are displayed in numerical order starting with the lowest and ending with the highest.
EXTRACTING DIAGNOSTIC CODES
1. Access the ECU from the floor board in front of the center console and position it for observing the diodes.
2. If the engine does not run, turn the key on and proceed to step #4.
3. Start the engine and warm it to operating temperature then idle.
Fig. 52 Selecting Modes:
4. Turn the diagnostic mode selector on the ECU fully clockwise until both diodes flash 3 times then turn the selector fully counterclockwise. The ECCS system is now in mode 3.
5. If the diodes do not illuminate, refer to Electrical Component And Circuit Diagnosis and perform the ECU Main Power And Ground Circuit test.
Fig. 55 Inspecting E.C.U. Lamps:
6. Observe the diodes and note the code(s) displayed.
Note: Code 55 indicates all systems are OK.
Fig. 33 Trouble Code Chart:
^Refer to the chart above for code identification and proceed to DIAGNOSTIC CHARTS for trouble code diagnosis.
ERASING DIAGNOSTIC CODES
1. Turn the ignition key on.
2. Turn the diagnostic mode selector on the ECU fully clockwise until both diodes flash 4 times then turn the selector fully counterclockwise. The ECCS system is now in mode 4.
3. Turn the ignition key off. This will return the ECCS system to mode #1 (normal operating mode).
ECU memory is now erased.