Toyota Sienna Service Manual: Check and replace ecu
• When no measuring condition is specified, perform the inspection with the engine stopped and the ignition switch on.
• Check that the connectors are fully seated. Check for loose, corroded or broken wires.
(a) First, check the ECU ground circuit. If it is faulty, repair it. If it is normal, the ECU could be faulty.
Temporarily replace the ECU with a normally functioning one and check if the symptoms occur. If the trouble symptoms disappear, replace the original ECU.
(1) Measure the resistance between the ECU ground terminal and body ground.
Standard resistance: Below 1 Ω
(2) Disconnect the ECU connector. Check the ground terminal on the ECU side and wire harness side for bending, corrosion or foreign matter. Lastly, check the contact pressure of the female terminals.
Check for short circuit
(a) If the wire harness is ground shorted (Fig. 5), locate the section by
conducting a resistance check with the body ground (below).
(b) Check the resistance with the body ground.
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Identification information
VEHICLE IDENTIFICATION AND SERIAL NUMBERS
1. VEHICLE IDENTIFICATION NUMBER
(a) The vehicle identification number is stamped on the
vehicle identification number plate and the
certification label, as shown in the illustration.
A:
Vehicle Identification Number Plate
B:
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Driving assist systems
To help enhance driving safety and performance, the following
systems operate automatically in response to various driving
situations. Be aware, however, that these systems are supplementary
and should not be relied upon too heavily when operating
the vehicle.
ABS (Anti-lock Brake System)
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Precaution
1. PRECAUTION OF HEADLIGHT BULB
REPLACEMENT
When any defects such as deformation, crack, dent,
chipping, etc. are identified on the discharge
headlight (especially, on the light control ECU),
replace it with a new one.
Even if the operation seems to be normal, the failsafe
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