Without Scan Tool

Fig. 137 Diagnostic Schematic:

When problems occur in ECU monitored input or output devices, test the system to find the cause. During testing, input and output device failures are retrieved from the ECU as malfunction code numbers flashed by the MIL lamp on the instrument panel.

NOTE: The ECU continuously checks for input device malfunctions. However, it only checks for output device malfunctions during a 3 second period after the ignition switch is turned "ON" with test connector grounded. If more than one failure code is present, the lowest number code is displayed first. Subsequent codes are displayed in numerical order.

INSPECTION PROCEDURE

Test Connector:

1. Warm engine to operating temperature and switch ignition "OFF."
2. Ground test connector (Green: 1-pin) with a jumper wire.
3. Turn ignition switch "ON."
4. If the MIL lamp illuminates ("CHECK") for approximately 3 seconds and then goes "OFF" and stays "OFF," no codes are present.
5. If the MIL lamp illuminates ("CHECK"), goes "OFF" and then starts flashing, codes are present.
6. Start the engine and check for additional codes.
7. If any codes are retrieved, repair the cause of the problem. Refer to DIAGNOSTIC CHARTS.

AFTER REPAIR PROCEDURE

1. Erase malfunction codes from ECU memory by disconnecting the negative battery cable and depressing the brake pedal for at least five seconds. Reconnect battery cable.
2. Ensure engine is at operating temperature and ground test connector.
3. Turn ignition switch "ON."
4. If the MIL light illuminates ("CHECK") for approximately 3 seconds and then goes "OFF" and stays "OFF," no codes are present.
5. If the MIL light illuminates ("CHECK"), goes "OFF" and then starts flashing, codes are present.
6. Start the engine and check for additional codes.
7. If any codes are retrieved, repair the cause and repeat after-repair procedure.