Symptom Confirmation and Diagnostic Trouble Codes
SYMPTOM CONFIRMATION AND DIAGNOSTIC TROUBLE CODEHINT:
The diagnostic system in the LEXUS LS430 has various functions.
- The first function is the Diagnostic Trouble Code (DTC) check. In a DTC check, a previous malfunction's DTC can be checked by a technician during troubleshooting. (A DTC is a code stored in the ECU memory whenever a malfunction in the signal circuits to the ECU occurs.)
- Another function is the Input Signal Check, which checks if the signals from various switches are sent to the ECU correctly.
By using these functions, the problem areas can be narrowed down and troubleshooting is more effective.
Diagnostic functions are incorporated in the following systems in the LEXUS LS430
- In the DTC check, it is very important to determine whether the problem indicated by the DTC is:
1. still occurring, or
2. occurred in the past but has since returned to normal.
In addition, the DTC should be compared to the problem symptom to see if they are related. For this reason, DTCs should be checked before and after confirmation of symptoms (i.e., whether or not problem symptoms exist) to determine current system conditions, as shown in the flowchart given.
Never skip the DTC check. Failure to check DTCs may, depending on the case, result in unnecessary troubleshooting for systems operating normally or lead to repairs not pertinent to the problem. Follow the procedures listed in the flowchart in the correct order.
Step 1 - 2:
Step 3 - 6:
- A flowchart showing how to proceed with troubleshooting using the DTC check is shown. Directions from the flowchart will indicate how to proceed either to DTC troubleshooting or to the troubleshooting of the problem symptoms.