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Low Volt Reading - Printable Version

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Low Volt Reading - Richard - 09-12-2007

My volt gauge is reading 11 volts and the red indicator light has come on as well. What is the best way to troubleshoot this to see if it is the battery, alternator, voltage regulator, etc.?



The car is in my garage so I'd like to see if I can get this done before I go to my mechanic.



Any help is appreciated.

Low Volt Reading - prj24149 - 09-12-2007

First step is to put a volt meter on the battery with the car running (preferably a digital volt meter). Should read 13 to 14 volts.

If not, I would pull the battery and take it to a parts store and check it.

Most parts stores or car battery stores have battery checking equipment.

If the battery is good, then its time to look at the alternator and voltage regulator. Though if the voltage is 13-14 volts with the car running that usually means they are working fine.

Many people here are more knowlegeable than me so they may have more ideas.



Along the same line, does anyone know if the meter can be adjusted from the back of it.

It is just a galvanometer and most of those have an adjusting screw in the back. Mine reads about 1volt low and I know from my DVM that the running voltage is 13.5V but the instrument gauge only reads 12.5V

Low Volt Reading - banditsc - 09-12-2007

[quote name='Richard' post='41089' date='Sep 12 2007, 11:07 AM']My volt gauge is reading 11 volts and the red indicator light has come on as well. What is the best way to troubleshoot this to see if it is the battery, alternator, voltage regulator, etc.?



The car is in my garage so I'd like to see if I can get this done before I go to my mechanic.



Any help is appreciated.[/quote]



Put a volt meter on the battery with the car off and see what the reading is, then start the car get another reading, and another with the RPM's up. If the voltage doesn't rise at all with the car running or revved then the alternator could be shot. If it is charging but low, it could be the voltage regulator, which there is a recent write up about this on here.

Low Volt Reading - Richard - 09-13-2007

Thanks for the replies and suggestions.



I got the car up on stands tonight and the tenisioner arm for the alternator belt was loose so the belt was slipping. The belt was worn a little so I am picking up a new one tomorrow.



Any other things that I should watch for since this happened?

Low Volt Reading - flash - 09-14-2007

when tensioning the alternator, do not torque down the mounting bolts until AFTER you have acheived tension on the belt - failure to do that will result in a broken mounting ear

Low Volt Reading - Richard - 09-14-2007

Flash, thanks for the tip, I will do that.



I got back under the car last night and the tensioner arm is actually broken so I am picking up one up today and will get to it this weekend.

Low Volt Reading - flash - 09-14-2007

yup - happens a lot - i am really amazed to see how many shops adjust these thigs without loosening the mounting bolts, and then how many others fail to re-torque them afterwards



there have been a lot of broken alternator ears and ac compressor ears over the last year, i think nearly all of them due to this - perfectly good units otherwise, forced to be replaced due to the shop not paying attention



good luck