Reading Diagnostic Trouble Codes

Self Constructed Led Test Light:

Fig. 5 Location of test connection.:

Note: Fault codes are displayed using an LED tester (US 1115 or Fig. 14), connected between the battery positive and the diagnostic test connector terminal (located between the right front strut tower and the air flow sensor) Fig. 5. If the permanent memory has been erased, or the temporary memory erased by restarting the engine, take a 5 minute test drive before extracting fault codes. If the engine will not start, crank the engine over for about 6 seconds. Fault memory can be initiated with the engine running or stalled.
1. Before extracting fault codes:
a. Fuses 13, 24, and 28, (for California also 12) must be good.
b. Ground connection to the intake manifold must be good.
c. Engine at normal operating temperature (80°C/176°F).
d. Engine speed must exceed 3000 rpm at least once.
e. Gas pedal must be fully depressed at least once (to trigger the full throttle switch), and the engine must idle for at least 2 minutes.
f. Fault lamp in instrument cluster (California) must be OK.
2. To start displaying the fault codes:
3. With the ignition OFF, connect LED tester US 1115 to the battery (+), and the test connector.
4. Without activating the starter, turn the ignition ON.
5. Bridge the terminals on top of the fuel pump relay with a spare fuse for at least 4 seconds. The LED tester should begin flashing.
6. If the fault lamp does not light up with the ignition on and after initiating the fault display, but does light up when the terminals on the fuel pump relay are bridged, check the wiring from the control unit to the fault lamp. If the wiring is not faulty, the injection control unit could be defective.
7. After the start signal (test lamp ON) and a pause (lamp OFF) of about 2.5 seconds, the flash code sequence will begin.
5. The code display will repeat itself until the fuse is inserted again in the fuel pump relay. At that time, either the next fault code or the "End of Fault Sequence" code (0000) will be displayed. The 0000 code is a continuous sequence of 2.5 second ON and OFF flashes.
8. After all fault codes have been displayed, erase the permanent fault code memory as follows:

Self Constructed Led Test Light:

a. Connect the LED tester (US 1115 or Fig. 14) to the battery (+) and the test connector.
b. Switch the ignition OFF and insert the fuse in the fuel pump relay.
c. Switch the ignition ON. The LED tester should light.
d. After 4 seconds, remove the fuse and the 0000 (end of fault code sequence) code should be displayed.
e. Insert the fuse again for about 10 seconds then remove.
f. If the test lamp lights up and stays lit, the fault code memory has been cleared.
9. To erase the temporary memory, restart the engine.
10. Test drive the car for about 5 minutes, then recheck fault memory.