Symptom Confirmation And Diagnostic Trouble Code Check: Notes
The diagnostic system in the LEXUS LX470 fulfills various functions. The first function is the Diagnostic Trouble Code Check in which a malfunction in the signal circuits to the ECU is stored in code in the ECU memory at the time of occurrence, to be output by the technician during troubleshooting. Another function is the Input Signal Check which checks if the signals from various switches are sent to the ECU correctly.
By using these check functions, the problem areas can be narrowed down quickly and troubleshooting can be performed effectively. Diagnostic functions are incorporated in the following systems in the LEXUS LX470.
| System | Diagnostic Trouble Code Check | Input Signal Check (Sensor Check) | Diagnostic Test Mode (Active Test) |
|---|---|---|---|
| Engine | X (with Check Mode) | X | X |
| Automatic Transmission | X (with Check Mode) | X | |
| Active Height Control Suspension & Adaptive Variable Suspension | X | ||
| ABS &Vehicle Stability Control (VSC) & Brake Assist (BA) System | X | X | X |
| Power Tilt and Power Telescopic Steering Column | X | ||
| Variable Gear Ratio Steering | X | X | |
| Supplemental Restraint System | X | ||
| Power Seat Control System | X | ||
| Wireless Door Lock Control System | X | ||
| Theft Deterrent System | X | X | |
| Cruise Control System | X | X | |
| Engine Immobiliser System | X | X | |
| Rain Sensor System | X | ||
| Sliding Roof System | X | ||
| Body Control System | X | X | |
| Driver Door Control System | X | X | |
| Multiplex Communication System | X | ||
| LEXUS Navigation System | X | ||
| LEXUS Link System | X | ||
| Air Conditioning System | X |
In diagnostic trouble code check, it is very important to determine whether the problem indicated by the diagnostic trouble code is still occurring or occurred in the past but returned to normal at present. In addition, it must be checked in the problem symptom check whether the malfunction indicated by the diagnostic trouble code is directly related to the problem symptom or not. For this reason, the diagnostic trouble codes should be checked before and after the symptom confirmation to determine the current conditions, as shown in the table below. If this is not done, it may, depending on the case, result in unnecessary troubleshooting for normally operating systems, thus making it more difficult to locate the problem, or in repairs not pertinent to the problem. Therefore, always follow the procedure in correct order and perform the diagnostic trouble code check.