− INTRODUCTION HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS IN−33 HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE 1. CONNECTOR CONNECTION AND TERMINAL IN- SPECTION For troubleshooting, diagnostic trouble code charts or problem symptom table are provided for each circuit with detailed inspection procedures on the following pages. When all the component parts, wire harnesses and con- nectors of each circuit except the ECU are found to be normal in troubleshooting, then it is determined that the problem is in the ECU. Accordingly, if diagnosis is per- formed without the problem symptoms occurring, refer to Step 8 to replace the ECU.
So always confirm that the problem symptoms are occurring, or proceed with inspec- tion while using the symptom simulation method. The instructions ”Check wire harness and connector” and ”Check and replace ECU” which appear in the inspection procedure, are common and applicable to all diagnostic trouble codes. Follow the procedure outlined below whenever these instructions appear. OPEN CIRCUIT: This could be due to a disconnected wire harness, faulty con- tact in the connector, and a connector terminal pulled out, etc. HINT: It is rarely the case that a wire is broken in the middle of it. Most cases occur at the connector.
In particular, care- fully check the connectors of sensors and actuators Faulty contact could be due to rusting of the connector terminals, to foreign materials entering terminals or a de- formation of connector terminals. Simply disconnecting and reconnecting the connectors once changes the condition of the connection and may result in a return to normal operation. Therefore, in troubleshooting, if no ab- normality is found in the wire harness and connector check, but the problem disappears after the check, then the cause is considered to be in the wire harness or con- nectors. SHORT CIRCUIT:
This could be due to a contact between wire harness and the body ground or to a short circuit occurred inside the switch, etc. HINT: When there is a short circuit between the wire harness and body ground, check thoroughly whether the wire harness is caught in the body or is clamped properly. IN089−02 FI0046 FI0047 FI0048 33 Author : Date: