Diagnostika OBD1 Dahaitsu

Accessing Diagnostic Trouble Codes

The ECU self diagnosis circuit detects and stores system malfunctions related to the various sensor and actuator circuits. These malfunctions are stored as DTCs in the ECU as long as battery voltage is applied to the ECU and the Check Engine lamp will remain On as long as the malfunction is present. By analyzing these DTCs, system malfunctions can be easily diagnosed and repaired.

To obtain DTCs stored in the ECU memory, close throttle valve fully and turn all accessory switches off, then proceed as follows:

1. Short terminals of check connector with check connector test harness tool No. 09991-87702-000, or equivalent.

Check connector test harness

1. Turn ignition On. Do not start engine.
2. DTCs stored in ECU will cause Check Engine warning lamp to flash.

Diagnostic Trouble Code Interpretation

1. Normal System operation is indicated by Check Engine lamp blinking once every 4.5 seconds.
2. If ECU has detected a system malfunction, Check Engine lamp will blink a number of times to equal to DTC with an interval of 2.5 seconds between DTCs. After all stored DTCs have been read, there will be a 4.5 second pause and all DTCs will repeat.

Clearing Diagnostic Trouble Codes

After service, the DTC retained in the ECU memory must be cleared by disconnecting the battery ground cable or removing the back-up fuse of the relay block assembly in the engine compartment for at least 10 seconds with the ignition turned Off.

Trouble Codes