Diagnostic questioning involves asking the customer about the conditions when the symptoms occurred to reproduce those symptoms.
1. What the technician must keep in mind when performing diagnostic questioning
• Not to use technical terms and speak in words unfamiliar to the customer.
• Ask the customer using examples so that the customer can easily answer.
Where: Right front tire?
When: When you are driving?
What do you do: If you depress the brake, can you hear the sound?
How: A squeaking sound can be heard?
Since when: When did the symptoms begin?
2. What the technician should understand about diagnostic questioning
When performing diagnostic questioning, it is essential for the technician to completely understand the conditions required to reproduce the symptoms that the customer points out.
(1) What the technician has to understand
• When the symptoms are reproduced: Confi rm the customer’s requests and demands
• When the symptoms are not reproduced: Confi rm the conditions required to reproduce the symptoms
(2) What the technician should ask the customer for reference
There is a list of questions that make it easier for the technician to troubleshoot if he has asked beforehand. But those are only for reference and the technician should not have any preconceptions or fi xed ideas.
Cases in diagnostic questioning (See “Basic Skills” of “Fundamentals of Troubleshooting” on PDF(2 of 2) Attachment A-1,A-2)
Reproducing the Symptoms
The thinking method when the technician reproduces the symptoms
When the technician attempts to reproduce the symptoms that the customer points out, he has to keep in mind the following points.
• To correctly troubleshoot, it is important to create conditions and circumstances that are similar to those that exist when the symptoms occur, based on the information gathered from diagnostic questioning.
1. Confi rm the symptoms through a road test
• This test should be performed under the conditions related to when the symptoms occur, based on the information obtained through diagnostic questioning and freeze frame data of ECU.
If possible, it is best to perform the road test with the customer.
2. Reproducing method when the vehicle is stopped
This test is performed when the vehicle is stopped in order to reproduce the symptoms whose reproductivity is low or that occur while driving.
(1) Check the diagnosis code
When a malfunction code is output
If the malfunction code is displayed, focus on the system relevant to that code to reproduce the symptoms using the reproduction method.
When a normal code is output
If the code is normal, focus on the actuator system that the diagnosis did not detect and reproduce the symptoms using the reproduction method.
(2) Reproduction method
(See “Reproduction method” of “Troubleshooting” in this chapter)
Judge Whether the Symptoms are Malfunction or Not
When the customer complains, it is important to determine whether the cause comes from the vehicle, the customer’s usage or both. It is also necessary to judge the customer’s vehicle performance whether the customer’s requirement is equal or not by comparing it to another vehicle of the same model. If the performance level is equal, it is nearly impossible to remove the cause of the complaint by repair, so the technician should judge that the complaint is not a malfunction symptom but the customer’s expectation, and deal with it from another perspective. If the level is considerably worse than that of another vehicle of the same model, the technician should judge that the complaint is a malfunction and perform troubleshooting. When the technician compares the customer’s vehicle with another vehicle of the same model.
• The driving conditions should be the same.
• If the technician cannot judge whether there is a malfunction or not, he should consult with several colleagues, evaluate and make a decision.