Car Information:
Toyota Sienna
Year: 2004
Engine Size: 3MZ-FE 6 cyl. 202 cubic inches
Trans: Automatic

Issue / Question:
We heard a whine when accelerating between 30 and 50 mph. The pitch starts low then transitions to very high before suddenly ceasing. It is louder outside the vehicle than inside. The whine has an electronic character vs. mechanical, like electronic noise from an alternator, but we have the radio turned off. Had transmission oil changed 2,000 miles ago and the whine stopped. Car shop said trans oil was clean with no debris or discoloration. The whine has now returned. The van has 80,000 miles.

Answer:
A noise of this nature can be caused by an alternator, power steering pump, or a restriction in the transmission cooler system, a restricted transmission cooler could be the problem and a flow test would be recommended.
Larry

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