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:
Installation
1. INSTALL REAR AXLE HUB & BEARING ASSEMBLY LH
(a) Install the hub & Bearing assembly LH with the 4
bolts.
Torque: 56 N*m (571 kgf*cm, 41 ft.*lbf)
2. INSPECT BEARING BACKLASH (See page AH-16)
3. INSPECT AXLE HUB DEVIATION (See page AH-16)
4. CONNECT SKID CONTROL SENSOR WIRE
(a) Co ...
Disposal
1. DISPOSE OF SHOCK ABSORBER ASSEMBLY REAR LH
(a) Fully extend the shock absorber rod.
(b) Using a drill, make a hole in the cylinder as shown in
the illustration to discharge the gas inside the
cylinder.
CAUTION:
When drilling, since the fragments may fly
out, work careful ...
Crankshaft Position - Camshaft Position Correlation
DESCRIPTION
Refer to DTC P0335 (See page ES-220).
MONITOR DESCRIPTION
DTC P0016 and P0018
The ECM optimizes the valve timing by using the VVT (Variable Valve Timing)
system to control the intake
camshaft. The VVT system includes the ECM, the Oil Control Valve (OCV) and the
VVT contr ...
