Reading Diagnostic Trouble Codes

Fig. 69 Trouble Code Example:

READING DIAGNOSTIC CODES
The 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 red diode on the ECU. The codes are interpreted by the number of times and duration the diode flashes.
The red diode will flash for 0.6 of a second with 0.6 of a second delay between flashes "X" number of times, this will represent units of ten.
Then there will be a delay 0.9 of a second and the red diode will flash for 0.3 of a second with 0.3 of a second delay between flashes "X" number of times, this will represent units of one.
There will be a delay of 2.1 seconds between codes.
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.

Fig. 35 Selecting Modes:

EXTRACTING DIAGNOSTIC CODES
1. Access the ECU from below the panel under the carpet on the passenger side floor board and position it for observing the diode.
2. Turn the ignition switch on (do not start the engine).
3. Confirm that the "CHECK ENGINE" lamp in the instrument panel illuminates.
If not, check the bulb and replace if faulty.
4. Turn the diagnostic mode selector on the ECU fully clockwise for at least two seconds then turn the selector fully counterclockwise. The ECCS system is now in mode 2.

Fig. 36 Inspecting E.C.U. Lamp:

5. Observe the diode and note the code(s) displayed.
NOTE: Code 55 indicates all systems are OK.





^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 and wait more than two seconds then turn the selector fully counterclockwise. The ECCS system is now in mode 2.
3. Turn the diagnostic mode selector on the ECU fully clockwise and wait more than two seconds then turn the selector fully counterclockwise. The ECCS system is now in mode 1.
ECU memory is now erased.