Toyota Sienna Service Manual: Symptom confirmation and diagnostic trouble code
HINT:
The diagnostic system in the SIENNA has various functions.
- The first function is the Diagnostic Trouble Code (DTC) check. A DTC is a code stored in the ECU memory whenever a malfunction in the signal circuits to the ECU occurs. In a DTC check, a previous malfunction's DTC can be checked by a 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 functions, the problem areas can be narrowed down and troubleshooting is more effective.
Diagnostic functions are incorporated in the following system in the SIENNA.
- In the DTC check, it is very important to determine whether the problem indicated by the DTC either: 1) still occurs, or 2) occurred in the past but has 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 below.
- Never skip the DTC check. Failing to check DTCs may, depending on the case, result in unnecessary troubleshooting for systems operating normally or lead to repairs not related to the problem. Follow the procedures listed in the flowchart in the correct order.
- The following flowchart shows how to proceed with troubleshooting using the DTC check. Directions from the flowchart will indicate how to proceed either to DTC troubleshooting or to the troubleshooting of each problem symptom.
- DTC CHECK
- MAKE A NOTE OF DTCS DISPLAYED AND THEN CLEAR MEMORY
- SYMPTOM CONFIRMATION
Result 
- SIMULATION TEST USING SYMPTOM SIMULATION METHODS
- DTC CHECK
Result 
- SYMPTOM CONFIRMATION
Result 
If a DTC was displayed in the initial DTC check, the problem may have occurred in a wire harness or connector in that circuit in the past. Check the wire harness and connectors.
| TROUBLESHOOTING OF EACH PROBLEM SYMPTOM |
The problem still occurs in a place other than the diagnostic circuit (the DTC displayed first is either for a past problem or a secondary problem).
Customer problem analysis
HINT:
In troubleshooting, confirm that the problem symptoms
have been accurately identified. Preconceptions should be
discarded in order to make an accurate judgment. To
clearly understand w ...
Symptom simulation
HINT:
The most difficult case in troubleshooting is when no
problem symptoms occur. In such a case, a thorough
problem analysis must be carried out. A simulation of the
same or similar conditions ...
Other materials:
Open or Short Circuit in ABS Solenoid Relay Circuit
DESCRIPTION
The ABS solenoid relay is built in the brake actuator assembly. This relay
supplies power to each ABS
solenoid. If the initial check is OK, after the ignition switch is turned to the
ON position, the relay goes on.
WIRING DIAGRAM
Refer to DTCs C0226/21, C0236/22, C0246/23 ...
Bluetooth Module Initialization Failed
DTC 57-47 Bluetooth Module Initialization Failed
DESCRIPTION
DTC No.
DTC Detection Condition
Trouble Area
57-47
Bluetooth module is not installed.
Problem with Bluetooth module
Problem in communication line to Bluetooth module
...
Side Airbag Sensor Assembly RH Circuit Malfunction
DTC B1140/32 Side Airbag Sensor Assembly RH Circuit Malfunction
DESCRIPTION
The side airbag sensor RH circuit consists of the center airbag sensor
assembly and side airbag sensor
RH.
If the center airbag sensor assembly receives signals from the side airbag
sensor RH, it judges whether or
...
