Have not found anything not working, removed.

ANONYMOUS

MEMBER
2006 SCION XB
90,000 MILES

Have not found anything not working, removed negative cable while idling, and engine does not stop. When replaced negative cable while idling, heard engine slow a little, I think alternator must work, to hear engine change when hooking back cable. Thank you, close call and driving 120 miles later today.

1 Reply

CARADIODOC

MECHANIC
33,874 POSTS

First of all you haven't given us a clue as to the problem. Second, you are very close to doing thousands of dollars worth of damage in a few seconds by removing the battery cable while the engine is running. Do that the first time in my shop and you get a very stern lecture in the boss's office. Do that twice and you're out the door. That was a trick done many years ago by mechanics who didn't understand how these simple systems work.

Every year I did a demonstration for my students to show what can happen by removing a cable. The battery is the key component in helping the voltage regulator maintain system voltage to a safe level. Without it in the circuit that voltage can very easily reach 30 or more volts. If you're lucky that will only destroy the diodes inside the generator and that's all you'll have to replace. If you're not so lucky you will destroy multiple computers and any lights that are turned on.

It takes five seconds to measure the battery voltage to see if the generator is working.