Toyota Highlander Service Manual: Ignition system (2AZ-FE)

Ignition

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On-vehicle inspection

NOTICE: In this section, the terms "cold" and "hot" refer to the temperature of the coils. "Cold"means approximately -10 C (14 F) to 50 C (122 F). "Hot" means approximately 50 C (122 F) to 100 C ...

More about Toyota Highlander:

If a warning light turns on or a warning buzzer sounds
Calmly perform the following actions if any of the warning lights comes on or flashes. If a light comes on or flashes, but then goes off, this does not necessarily indicate a malfunction in the system. However, if this continues to occur, have the vehicle inspected by your toyota dealer. Warnin ...