Symptom Simulation Methods

SYMPTOM SIMULATION
The most difficult case in troubleshooting is when there are no problem symptoms occurring. in such cases, a thorough customer problem analysis must be carried out, then simulate the same or similar conditions and environment in which the problem occurred in the customer's vehicle. No matter how much experience a technician has, or how skilled he may be, if he proceeds to troubleshoot without confirming the problem symptoms he will tend to overlook something important in the repair operation and make a wrong guess somewhere, which will only lead to a standstill. For example, for a problem which only occurs when the engine is cold, or for a problem which occurs due to vibration caused by the road during driving, etc., the problem can never be determined so long as the symptoms are confirmed with the engine hot condition or the vehicle at a standstill. Since vibration, heat or water penetration (moisture) are likely causes for problems which are difficult to reproduce, the symptom simulation tests introduced here are effective measures in that the external causes are applied to the vehicle in a stopped condition.

Important Points in the Symptom Simulation Test
In the symptom simulation test, the problem symptoms should, of course be confirmed, but the problem area or parts must also be found out. To do this, narrow down the possible problem circuits according to the symptoms before starting this test and connect a tester beforehand. After that, carry out the symptom simulation test, judging whether the circuit being tested is defective or normal and also confirming the problem symptoms at the same time. Refer to the "Matrix Chart Of Problem Symptoms" under Diagnosis By Symptom for each system to narrow down the possible causes of the symptom.

VIBRATION METHOD (When vibration seems to be the major cause)
- CONNECTORS: Slightly shake the connector horizontally and vertically.

- WIRE HARNESS: Slightly shake the harness horizontally and vertically. Pay special attention for harness damage and to places where the harness passes through a body opening or is anchored, allowing a fulcrum point for a vibration.

- PARTS AND SENSORS: Apply slight vibration by tapping with your finger on the part or sensor that is considered to be a possible problem.

HEAT METHOD (When high temperature seems to be the cause of the problem)
- Heat suspected component with a hair drier or similar device.

CAUTION:
^ To avoid damage to components, do not heat to more than 60°C (140°F).
^ Do not apply heat directly parts in ECM.

WATER SPRINKLING METHOD (When the malfunction seems to be related to high-humidity conditions)
- Sprinkle water onto the vehicle to see if malfunction occurs.

CAUTION:
^ Never sprinkle water directly into engine compartment, but indirectly by applying spray to the radiator front surface.
^ Never apply water directly to electronic components.

OTHER: (When a malfunction seems to occur when electrical load is excessive)
- Turn on all electrical loads including heater blower, head lights, rear de-fogger, etc., and check for malfunction to occur.