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DIAGNOSIS & TESTING
Diagnosis Help
1. Connect X-431 3G diagnostic tester (the latest software) to Data Link Connector (DLC), and make it
communicate with vehicle electronic module by the data network.
2. Confirm that the malfunction exists, and perform the diagnosis tests and service procedures.
3. If the Diagnostic Trouble Codes (DTC) cannot be cleared, it indicates that there is a current malfunction.
4. Only the digital multimeter can be used when measuring the voltage of the electronic system.
5. Refer to any Technical Bulletin applied to the malfunction.
6. Visually check the related wire harness.
7. Check and clean the Electronic Power Steering controller (EPS controller) ground related to the latest
DTC.
8. If numerous trouble codes are set, refer to the circuit diagram and look for any common ground circuit or
power supply circuit applied to the DTC.
Intermittent DTC Troubleshooting
If it is an intermittent problem, perform the following procedures:
1. Check the connector for looseness.
2. Check the wire harness for wear, piercing, pinch or partial break.
3. Observe the diagnostic tester data related to this circuit.
4. Wiggle the related wire harness and connector and observe if the signal is interrupt in the related circuit.
5. Try to duplicate the conditions under which the DTC is set.
6. Check for the data that has changed or the DTC that has been reset during the wiggle test.
7. Check if the terminals are broken, bent, protruded out or corroded.
8. Check the sensor and mounting area for any condition that would result in an incorrect signal, such as
damage, foreign matter.
9. A data recorder and/or oscilloscope can be helpful in diagnosing the intermittent malfunction.
Ground Inspection
Groundings are often exposed to moisture, dirt or other corrosive areas. Corrosion (rust) may form additional
resistance. This additional resistance will change the way in which a circuit works. A loose or corroded ground
can drastically affect the electronically controlled circuit. Perform the following operations:
1. Remove the ground bolt or nut.
2. Check all the contact surfaces for tarnish, dirt, rust, etc.
3. Clean as necessary to ensure that the contacting is in a good condition.
4. Reinstall the bolt or nut securely.
5. Check for the accessories which may interfere with the ground circuit.
6. If several wires are crimped into one ground terminal, check for proper crimps. Make sure that all the wire
harnesses are clean, securely fastened and good contacted without crimping any excessive insulation
coat.