Toyota RAV4 manuals

Toyota Sienna Service Manual: 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 and environment in which the problem occurred in the customer's vehicle should be carried out. No matter how much skill or experience a technician has, troubleshooting without confirming the problem symptoms will lead to important repairs being overlooked and mistakes or delays.

For example:

With a problem that only occurs when the engine is cold or as a result of vibration caused by the road during driving, the problem can never be determined if the symptoms are being checked on a stationary vehicle or a vehicle with a warmed-up engine. Vibration, heat or water penetration (moisture) is difficult to reproduce. The symptom simulation tests below are effective substitutes for the conditions and can be applied on a stationary vehicle. Important points in the symptom simulation test: In the symptom simulation test, the problem symptoms as well as the problem area or parts must be confirmed. First, narrow down the possible problem circuits according to the symptoms. Then, connect the tester and carry out the symptom simulation test, judging whether the circuit being tested is defective or normal. Also, confirm the problem symptoms at the same time.

Refer to the problem symptoms table for each system to narrow down the possible causes.

Symptom simulation

(a) VIBRATION METHOD: When a malfunction seems to occur as a result of vibration.

(1) PART AND SENSOR

Apply slight vibration with a finger to the part of the sensor suspected to be the cause of the problem, and check whether or not the malfunction occurs.

NOTICE: Applying strong vibration to relays may open relays.

(2) CONNECTORS

Slightly shake the connector vertically and horizontally.

(3) WIRE HARNESS

Slightly shake the wire harness vertically and horizontally.

HINT:

The connector joint and fulcrum of the vibration are the major areas that should be checked thoroughly.

(b) HEAT METHOD: When a malfunction seems to occur when the area in question is heated.

(1) Heat the component that is the possible cause of the malfunction with a hair dryer or similar device. Check if the malfunction occurs.

NOTICE:
  • Do not heat to more than 60°C (140°F).

    Exceeding this temperature may damage the components.

  • Do not apply heat directly to the parts in the ECU.

Symptom simulation

(c) WATER SPRINKLING METHOD: When a malfunction seems to occur on a rainy day or in high-humidity.

(1) Sprinkle water onto the vehicle and check if the malfunction occurs.

NOTICE:
  • Never sprinkle water directly into the engine compartment. Indirectly change the temperature and humidity by spraying water onto the front of the radiator.
  • Never apply water directly onto the electronic components.

HINT:

If the vehicle has or had a water leakage problem, the leakage may have damaged the ECU or connections. Look for evidence of corrosion or short circuits. Proceed with caution during water tests.

Symptom simulation

(d) HIGH ELECTRICAL LOAD METHOD: When a malfunction seems to occur when electrical load is excessive.

(1) Turn on the heater blower, headlight, rear window defogger and all other electrical loads.

Check if the malfunction reoccurs.

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 malfunctio ...

Diagnostic trouble code chart
Look for output Diagnostic Trouble Codes (DTCs) (from the DTC checks) in the appropriate section's Diagnostic Trouble Code Chart. Use the chart to determine the trouble area and the proper inspecti ...

Other materials:

Vehicle battery
General information The battery is maintenance-free. More information about the battery can be requested from a dealer's service center or another qualified service center or repair shop. Safety information Warning Vehicle batteries that are not compatible can damage vehicle systems and impair veh ...

Removal
1. REMOVE BATTERY (See page EM-26) 2. REMOVE NO. 2 AIR CLEANER INLET (See page EM- 28) 3. REMOVE AIR CLEANER CAP SUB-ASSEMBLY (See page FU-13) 4. REMOVE AIR CLEANER FILTER ELEMENT (See page EM-28) 5. REMOVE AIR CLEANER CASE SUB-ASSEMBLY (See page EM-28) 6. REMOVE AIR CLEANER BRACKET (a ...

Engine assembly
Components REMOVAL 1. DISCHARGE FUEL SYSTEM PRESSURE (See page FU-13) 2. DISCHARGE REFRIGERANT FROM REFRIGERATION SYSTEM (See page AC-172) 3. REMOVE BATTERY (a) Disconnect the negative battery terminal. (b) Disconnect the positive battery ...

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