DIAGNOSIS & TESTING
Diagnostic Help
1. The X-431 scan tool connects to the Data Link Connector (DLC) and communicates with the vehicle electronic
modules through the class two serial data circuit.
2. Confirm that the malfunction is current and carry-out the diagnostic tests and repair procedures.
3. If the DTC cannot be deleted, it is a current fault.
4. Use a digital multimeter to perform voltage readings on electronic systems.
5. Refer to any Technical Bulletins that issued.
6. Visually inspect the related electrical wiring harness.
7. Inspect and clean all Immobilizer control module grounds that are related to the DTC.
8. If numerous trouble codes were set, use the electrical schematic and look for any common ground circuits or
voltage supply circuits that may apply to the DTC.
Intermittent DTC Troubleshooting
If the failure is intermittent, perform the following:
• Check for loose connectors.
• Look for any chafed, pierced, pinched, or partially broken wires.
• Monitor the scan tool data relative to this circuit.
• Wiggle the related electrical wiring harness and connectors while looking for an interrupted signal on the
affected circuit.
• If possible, try to duplicate the conditions under which the DTC set.
• Look for the data to change or for the DTC to reset during the wiggle test.
• Look for broken, bent, pushed out or corroded terminals.
• Inspect the sensor and mounting area for any condition that would result in an incorrect signal, such as dam-
age or foreign material.
• A data recorder, and/or oscilloscope should be used to help diagnose intermittent conditions.
Ground Inspection
Ground connections are very important to the proper operation of electrical and electronic circuits. Ground connec-
tions are often exposed to moisture, dirt and other corrosive elements. The corrosion (rust) can become an unwanted
resistance. This added resistance can alter the way a circuit works.
Electronically controlled circuits are very sensitive to proper grounding. A loose or corroded ground can drastically
affect an electronically controlled circuit. A poor or corroded ground can effect the circuit. Perform the following when
inspecting a ground connection:
1. Remove the ground bolt or screw.
2. Inspect all mating surface for tarnish, dirt, rust, etc.
3. Clean as required to assure good contact.
4. Reinstall bolt or screw securely.
5. Inspect for 9add-on9 accessories which may be interfering with the ground circuit.
6. If several wires are crimped into one ground eyelet terminal, check for proper crimps. Make sure all of the wires
are clean, securely fastened and providing a good ground path. If multiple wires are crimped to one eyelet, make
sure no excess wire insulation has been crimped creating a bad ground.
Diagnostic Tools
• Diagnostic Scan Tool X-431
• Digital Multimeter
• Jumper Wire
15
15–121
Chery Automobile Co., Ltd.
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