Toyota Camry

 XV30 (2002–2006) Service Manual

Introduction » How to troubleshoot ecu controlled systems
Symptom confirmation and diagnostic trouble code

HINT:
The diagnostic system in the CAMRY 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 CAMRY:

• 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 conditions, as shown in the table below
• 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 above in the correct order.
• A flow chart showing how to proceed with troubleshooting using the DTC check is shown below. Directions from the flow chart will indicate how to proceed either to DTC troubleshooting or to the troubleshooting of the problem symptoms table.

1 DTC CHECK

2 MAKE A NOTE OF DTCS DISPLAYED AND THEN CLEAR THE MEMORY

3 SYMPTOM CONFIRMATION

Go to step 5

4 SIMULATION TEST USING THE SYMPTOM SIMULATION METHODS

5 DTC CHECK

Troubleshooting of problem indicated by DTC

6 SYMPTOM CONFIRMATION

If a DTC was displayed in the initial DTC check, it indicates that the trouble may have occurred in a wire harness or connector in that circuit in the past. Therefore, check the wire harness and connectors

SYSTEM NORMAL

TROUBLESHOOTING OF EACH PROBLEM SYMPTOM

The problem is still occurring in a place other than the diagnostic circuit (the DTC displayed first is either for a past problem or a secondary problem).

General information

How to proceed with troubleshooting

Customer problem analysis

Symptom confirmation and diagnostic trouble code

Symptom simulation

Diagnostic trouble code chart

Problem symptoms table

Circuit inspection

Electronic circuit inspection procedure