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).
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 ...
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:
Brake Switch
DESCRIPTION
The stop light switch is a duplex system that transmits two signals: STP and
ST1-. These two signals are
used by the ECM to monitor whether or not the brake system is working properly.
If the signals, which
indicate the brake pedal is being depressed or released, are detected ...
Registration
HINT:
Register the recognition code when replacing the door
control transmitter or the door control receiver.
Add mode is used to register new recognition codes while
still retaining codes already registered. This mode is used
when a new transmitter is added. If the number of ...
Clearance warning ECU
COMPONENTS
REMOVAL
1. REMOVE FRONT DOOR SCUFF PLATE LH
2. REMOVE COWL SIDE TRIM BOARD LH
3. REMOVE INSTRUMENT PANEL FINISH PANEL SUBASSEMBLY LOWER LH
4. REMOVE NO. 1 INSTRUMENT PANEL SAFETY PAD INSERT SUB-ASSEMBLY
5. REMOVE CLEARANCE WARNING ECU
Disconnect each connector.
&nb ...