How to Use the Diagnostic Chart and Inspection Procedure

HOW TO USE THE DIAGNOSTIC CHARTS AND INSPECTION PROCEDURES
1. For troubleshooting, diagnostic trouble code charts or problem symptom charts are provided for each circuit with detailed inspection procedures.
2. When all the component parts, wire harnesses and connectors of each circuit except the ECM are found to be normal in troubleshooting, then it is determined that the problem is in the ECM. Accordingly, if diagnosis is performed without the problem symptoms occurring, the instruction will be to check and replace the ECM, even if the problem is not in the ECM. 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 ECM" which appear in the inspection procedure, are common and applicable to all diagnostic trouble codes.
Follow the procedure outlined below whenever these instructions appear.

IF THE INSTRUCTION IS "CHECK WIRE HARNESS AND CONNECTOR"
The problem in the wire harness or connector is an OPEN CIRCUIT or a SHORT CIRCUIT.

OPEN CIRCUIT:
This could be due to a disconnected wire harness, faulty contact in the connector, a connector terminal pulled out, etc.



HINTS:
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.


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.

CONTINUITY CHECK (OPEN CIRCUIT CHECK)



(a) Disconnect the connectors at both ECM and sensor sides.
(b) Measure the resistance between the applicable terminals of the connectors.
Resistance: 1.0 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 terminals when inserting the tester probes.

RESISTANCE CHECK (SHORT CIRCUIT CHECK)
(a) Disconnect the connectors at 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: 1.0 M Ohm or higher
HINT: Measure the resistance while lightly shaking the wire harness vertically and horizontally.

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



(c) 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 lightly.



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

To see how these checks should be performed, refer to "Circuit Check Examples".
Examples of Circuit Inspections


IF THE INSTRUCTION IS "CHECK AND REPLACE ECM"
First check the ECM ground circuit. If it is faulty, repair it. If it is normal, the ECM could be faulty, so replace the ECM with a known good one and check if the symptoms appear.




(a) Measure the resistance between the ECM ground terminal and the body ground.
Resistance: 1 Ohm or less




(b) Disconnect the ECM connector, check the ground terminals on the ECM side and the wire harness side for bend and check the contact pressure.