Reading and Clearing Diagnostic Trouble Codes

Codes 11 - 13 (Code Numbers Are In The 4th Column):

Codes 14 - 25 (Code Numbers Are In The 4th Column):

Codes 41 - 43 (Code Numbers Are In The 4th Column):

DIAGNOSTIC CODE INTERPRETATION

The Engine Control Unit (ECU) monitors operation of the emission control system. Some components are monitored continously, others only during specified operating conditions. When the ECU detects a malfunction lasting longer than a specified period of time the ECU will generate an error code that can be detected at the diagnostic connector.

There are fifteen diagnostic items (including normal operation) that will generate diagnostic codes. These codes can be read out using a voltmeter by refering the diagnostic codes chart. The malfunction codes are erased when the vehicle battery is disconnected for more than fifteen seconds. Note! If the oxygen sensor is disconnected during engine operation for testing purposes a code will be stored and must be cleared after the test is complete. Do not however disconnect the battery with the ignition on or the engine running as permenant damage to the vehicle electronic components may result. If multiple malfunctions occur the diagnostic codes will be sent sequentially beginning with the lowest number code.

Fig. 49 Component Locations (Self Diagnosis Connector Viewed From Pass. Comp.):

READING DIAGNOSTIC CODES

1. Connect an analog voltmeter to the ground and self diagnosis output pin of the diagnostic connnector.

2. Set the ignition switch to "ON".

3. Note the pattern of pulses displayed on the voltmeter.

4. Refer to the diagnostic codes chart to determine which device is causing the malfunction code.

5. Test and repair the offending components as necessary.

6. Clear the malfunction codes by disconnecting the vehicle battery negative terminal for fifteen seconds or longer.

7. Road test the vehicle and recheck for newly stored diagnostic codes.