D 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: D 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. D 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 between the wire harness and body ground, check thoroughly whether the wire harness is caught in the body or is clamped properly.
IN0379 Sensor Side ECU Side IN0378 Sensor Side ECU Side IN0380 Sensor Side ECU Side IN0381 Pull Lightly Looseness of Crimping IN–28 – INTRODUCTION HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS 28 AuthorĂ: DateĂ: 1997 LEXUS ES300 (RM511U) 2. CONTINUITY CHECK (OPEN CIRCUIT CHECK) (a) Disconnect the connectors at both ECU and sensor sides. (b) Measure the resistance between the applicable terminals of the connectors. Resistance: 1 Ω or less HINT: D Measure the resistance while lightly shaking the wire har- ness vertically and horizontally. D When tester probes are inserted into a connector, insert the probes from the back. For waterproof connectors in which the probes cannot be inserted from the back, be careful not to bend the terminals when inserting the tester probes. 3. RESISTANCE CHECK (SHORT CIRCUIT CHECK) (a) Disconnect the connectors on both ends. (b) Measure the resistance between the applicable terminals of the connectors and body ground. Be sure to carry out this check on the connectors on both ends. Resistance: 1 M Ω or higher HINT: Measure the resistance while lightly shaking the wire harness vertically and horizontally. 4. VISUAL CHECK AND CONTACT PRESSURE CHECK (a) Disconnect the connectors at both ends. (b) Check for rust or foreign material, etc. in the terminals of the connectors. (c) Check crimped portions for looseness or damage and check that the terminals are secured in lock portion. HINT: The terminals should not come out when pulled lightly.
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