How To Use The Diagnostic Chart And Inspection: Procedure

Connector Connection And Terminal Inspection
- For troubleshooting, diagnostic trouble code (DTC) charts or problem symptom table are provided for each circuit with detailed inspection procedures in this manual.
- When component parts, wire harnesses and connectors of each circuit are found to be normal in troubleshooting, the problem is most likely in the ECU. Accordingly, if diagnosis is performed without the problem symptoms occurring, refer to Step 8 to replace the ECU. Always confirm that the problem symptoms are occurring, or proceed with inspection while using the symptom simulation method.
  
  Fig 1: Inspecting Connector Connection (1 of 2)
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
- The instructions "Check wire harness and connector" and "Check and replace ECU" which appear in the inspection procedure are common and applicable to all DTCs. Follow the procedure outlined below whenever these instructions appear.
  
  Fig 2: Inspecting Connector Connection (2 of 2)
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OPEN CIRCUIT:

An open circuit the result of a disconnected wire harness, a faulty contact in the connector, a connector terminal pulled out, etc.

Fig 3: Locating Open Circuit
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NOTE:
- A wire is rarely broken in its middle. Most problem occur at the wire ends. Carefully check the connectors of sensors and actuators.
- Faulty contacts could be due to the rusting, contamination, and/or deformation of connector terminals. In some cases: 1) simply disconnecting and reconnecting the connectors will fix the problem, or 2) even though no abnormality is found in the wire harness or connector, the problem disappears after the check (meaning the cause was most likely in the wire harness or connectors).
SHORT CIRCUIT:

A short circuit could be the result of contact between the wire harness and the body ground or a short circuiting switch.

NOTE: When there is a short circuit between the wire harness and body ground, check thoroughly it wire harness is caught in the body or is clamped properly.
Connector Handling

Fig 4: Inserting Tester Probes Into Connector
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When inserting tester probes into a connector, insert them from the rear of the connector. When necessary, use mini test leads. For water resistant connectors which cannot be accessed from behind, take good care not to deform the connector terminals.
Continuity Check (Open Circuit Check)
1. Disconnect the connectors at both ECU and sensor sides.
  
  Fig 5: Disconnecting Connector At Both ECU Sensor Side
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2. Measure the resistance between the applicable terminals of the connectors.
  
  Fig 6: Measuring Resistance B/W Applicable Terminal Of Connectors
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Resistance: 1 Ω or less
NOTE: Measure the resistance while lightly shaking the wire harness vertically and horizontally.
Resistance Check (Short Circuit Check)
1. Disconnect the connectors on both ends.
2. 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.
  
  Fig 7: Measuring Resistance B/W Applicable Terminals Of Connectors
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Resistance: 10 kΩ or higher
NOTE: Measure the resistance while lightly shaking the wire harness vertically and horizontally.
Visual Check And Contact Pressure Check
1. Disconnect the connectors at both ends.
2. Check for rust or foreign material, etc. in the terminals of the connectors.
3. Check crimped portions for looseness or damage and check that the terminals are secured in the lock portion.
  
  Fig 8: Check Crimped Portions For Looseness Or Damage
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  NOTE: The terminals should not come out when pulled lightly from the back.
4. Prepare a test male terminal and insert it in the female terminal, then pull it out.
NOTE: When testing a gold-plated female terminal, always use a gold-plated male terminal.

NOTE: If a test terminal is easier to pulled out than others, there may be poor contact in that section.
Check Open Circuit
For the open circuit in the wire harness performs a continuity Check (step ( a) below) or a voltage check (step ( b) below).

Fig 9: Identifying Open Circuit In Wire Harness
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1. Check the continuity.
  1. Disconnect connectors A and C and measure the resistance between them.
    In the case of Fig. 2:
    
    Between terminal 1 of connector A and terminal 1 of connector C --> No continuity (open)
    
    Between terminal 2 of connector A and terminal 2 of connector C --> Continuity
    
    An open circuit exists in the wire harness between terminal 1 of A and terminal 1 of C.
    
    Fig 10: Measuring Resistance B/W A & C For Checking Continuity
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. Disconnect connector B and measure the resistance between the connectors.
    Between terminal 1 of connector A and terminal 1 of connector B1 Ω Continuity
    
    Between terminal 1 of connector B2 and terminal 1 of connector C --> No continuity (open)
    
    An open circuit exists in the wire harness between terminal 1 of B2 and terminal 1 of C.
  Fig 11: Measuring resistance b/w connector for checking Continuity
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Check the voltage.
  
  Fig 12: Checking Voltage B/W Terminals
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  In a circuit in which voltage is applied to the ECU connector terminal, an open circuit can be checked for by conducting a voltage check.
  
  With each connector still connected, measure the voltage between body ground and terminal 1 of connector A at the ECU 5V output terminal, terminal 1 of connector B, and terminal 1 of connector C (in that order).
Example results:
1. 5V: Between Terminal 1 of connector A and Body Ground
2. 5V: Between Terminal 1 of connector B and Body Ground
3. 0V: Between Terminal 1 of connector C and Body Ground
In the above example, an open circuit is in the wire harness between terminal 1 of B and terminal 1 of C.
Check Short Circuit
If the wire harness is ground shorted locate the section by conducting a continuity check with ground below.

Fig 13: Locating Short
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Check the continuity with ground.
1. Disconnect connectors A and C and measure the resistance between terminal 1 and 2 of connector A and body ground.
  Between terminal 1 of connector A and body ground --> Continuity (short)
  
  Between terminal 2 of connector A and body ground --> No continuity
  
  A short circuit is between terminal 1 of connector A and terminal 1 of connector C.
  
  Fig 14: Measuring Resistance B/W Terminals Of Connector & Body Ground
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect connector B and measure the resistance between terminal 1 of connector A and body ground, and terminal 1 of connector B2 and body ground.
  Between terminal 1 of connector A and body ground --> No continuity
  
  Between terminal 1 of connector B2 and body ground --> Continuity (short)
  
  A short circuit is between terminal 1 of connector B2 and terminal 1 of connector C.
Fig 15: Measuring Resistance B/W Terminals Of Connector A & Connector B2
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Check And Replace ECU
First check the ECU ground circuit. If it is faulty, repair it. If it is normal, the ECU could be faulty. Replace the ECU with a and check if the symptoms appear.
1. Measure the resistance between the ECU ground terminal and the body ground.
  Resistance: 1 Ω or less
  
  Fig 16: Measuring Resistance
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2. Disconnect the ECU connector. Check for bent ground terminals (on the ECU side and the wire harness side). Lastly, check the contact pressure.
Fig 17: Disconnecting ECU Connector
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