Expert: Sean Halliday - 2/1/2008

Question
QUESTION: My friend has a '94 corolla DX 2dr ht that runs quite well and until now has had no down time history. Recently he started the car to come to work and it ran perfectly in the driveway as usual until he turned on the lights. BAM!,
the motor died instantly. He turned off the lights and the car restarted right away and ran flawlessly until he turned on the lights and the car died instantly. My friend claims that there are no trouble lights and has not perused the problem yet for lack of finances. Can you help?

ANSWER: Look at the alternator to see if it is charging.use a meter and it should read between 13v and 14.5

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QUESTION: Alternator and cables checks out OK. Car will drive all day
until you turn on the lights.

ANSWER: Did you load test the battery?

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QUESTION: Local Midas shop said they did.....

Answer
If the battery is ok it must be the alternator.There is no other way for a major power drain to the ignition.When you turn on the lights,the reason the engine stops is because of a power drop and the motor cannot run with both at the same time.The demand on the alternator is too much.The alternator must read 14.00 volts with lights on and engine running.This is approx as it may vary betweeen 13.45 and 14.00 anything less then 12.75 and the alternator is faulty.