How to Use the Diagnostic Chart and Inspection Procedure

HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE
1. For troubleshooting, diagnostic trouble code charts or problem symptom charts are provided for each circuit. Detailed component or circuit inspection procedures are also included under inspection procedures for each component.
2. When all the component parts, wire harnesses and connectors 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 performed without the problem symptoms occurring, the instruction will be to check and replace the ECU, even if the problem is not in the ECU. So, always confirm that the problem symptoms are occurring, or proceed with inspection while using the symptom simulation method.
3. 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.

FOR RESULT: Check Wire Harness And Connector






- The problem in the wire harness or connector is (A) an open circuit or (B) a short circuit.

(A) OPEN CIRCUIT:
This could be due to a disconnected wire harness, faulty contact in the connector, a connector terminal pulled out, etc.
HINT:
1. It is rarely the case that a wire is broken in the middle of it. Most cases occur at the connector. In particular, carefully check the connectors of sensors and actuators.
2. Faulty contact could be due to rusting of the connector terminals, to foreign materials entering terminals or a drop in the contact pressure between the male and female terminals of the connector. 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 abnormality 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 connectors.

(B) SHORT CIRCUIT:
This could be due to a short circuit between the wire harness and the body ground or to a short 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.


CHECKING FOR OPEN CIRCUIT
(1) CONTINUITY CHECK



- Disconnect the connectors at both ECU and sensor sides.



- Measure the resistance between the applicable terminals of the connectors.

Resistance: 1 Ohm or less

HINT:
- Measure the resistance while lightly shaking the wire harness vertically and horizontally.
- 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 termianls when inserting the tester probes.

(2) VISUAL CHECK AND CONTACT PRESSURE CHECK
- Disconnect the connectors at both ends.
- Check for rust or foreign material, etc. on the terminals of the connectors.



- Check crimped portions for looseness or damage and check if the terminals are secured in the lock position.
HINT: The terminals should not come out when pulled light{y.



- Prepare a test male terminal and insert it in the female terminal, then pull it out.
HINT: If the test terminal is pulled out more easily than others, there may be poor contact in that section.


CHECKING FOR SHORT CIRCUIT
(1) RESISTANCE CHECK
- Disconnect the connectors at both ends.



- 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 MOhm or higher

HINT: Measure the resistance while lightly shaking the wire harness vertically and horizontally.


FOR RESULT: Check And Replace ECU
- HOW TO PROCEED:
- First check the ECU ground circuit.
- If it is faulty, repair it.
- If it is normal, the ECU could be faulty, so replace the ECU with a known good one and check if the symptoms appear.