Burned Out Battery (Alternator) Light Indictor...Major Drain
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Burned Out Battery (Alternator) Light Indictor...Major Drain
Hey guys, I was wondering how many of you know that if the battery/alternator light bulb blows, that it will cause a negative drain on battery. Yesterday I started my car and let it idle to warm up, but did not realize that when I turned the ignition switch on the battery/alternator light was not on. When I turned the car off, it would not start. First I thought the battery was dead. So I waited about 10 minutes and the cars started right up. Then I thought I needed an alternator. Today, when checked the battery and alternator voltage, it was reading 11.2 volts. I know that it should 14. I called my mechanic, Wayne, and he told me to turn the ignition switch on and see if the battery/alternator light was on, I told him..NO! He told me to pull the cluster out and replace the bulb, then check to voltage, which I did...now it is reading 14.02 volts. WOW! Problem solved! Saved a couple hundred bucks! Car is cranking and running great.
I have owned this car for 35 years and had never heard that before. You learn something new every day. I wonder how many people have replaced their alternator, (as I was about to do); or replaced the battery because of a $2 bulb, (which I have a bunch of). Just curious and passing on some info. I truly thank God for my mechanic, Wayne Lins. Great car brain.
I have owned this car for 35 years and had never heard that before. You learn something new every day. I wonder how many people have replaced their alternator, (as I was about to do); or replaced the battery because of a $2 bulb, (which I have a bunch of). Just curious and passing on some info. I truly thank God for my mechanic, Wayne Lins. Great car brain.
Re: Burned Out Battery (Alternator) Light Indictor...Major Drain
This is fairly well-known, but it's not intuitively obvious. This was also an issue on GM cars that used a similar circuit to excite the alternator.
FWIW, later instrument clusters have a resistor parallel to the bulb so that if the bulb blows, the alternator will still get power from that circuit.
FWIW, later instrument clusters have a resistor parallel to the bulb so that if the bulb blows, the alternator will still get power from that circuit.
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- Posts: 217
- Joined: Aug 20, 2007 11:50 PM
- Location: Decatur, GA
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Re: Burned Out Battery (Alternator) Light Indictor...Major Drain
Thanks Shawn. 35 years and never had the issue until yesterday. Glad to know some-one else is up on that revelation.Shawn D. wrote: ↑Feb 17, 2021 8:27 PM This is fairly well-known, but it's not intuitively obvious. This was also an issue on GM cars that used a similar circuit to excite the alternator.
FWIW, later instrument clusters have a resistor parallel to the bulb so that if the bulb blows, the alternator will still get power from that circuit.
Re: Burned Out Battery (Alternator) Light Indictor...Major Drain
It was a fairly common issue on 2002s, too.
Re: Burned Out Battery (Alternator) Light Indictor...Major Drain
These cheap voltmeters are useful tools, if and when you remember to look at them
Re: Burned Out Battery (Alternator) Light Indictor...Major Drain
https://www.amazon.com/gp/product/B00YA ... UTF8&psc=1
My check panel came apart easily so installing the meter wasn't difficult.
Re: Burned Out Battery (Alternator) Light Indictor...Major Drain
Fords do this too. Not so much a drain, just it doesn't turn the alternator on. There is a resistor but its on the cluster so it doesn't work if you have that out for whatever reason.Shawn D. wrote: ↑Feb 17, 2021 8:27 PM This is fairly well-known, but it's not intuitively obvious. This was also an issue on GM cars that used a similar circuit to excite the alternator.
FWIW, later instrument clusters have a resistor parallel to the bulb so that if the bulb blows, the alternator will still get power from that circuit.
I had a Beetle years ago that wouldn't charge, same thing with the bad bulb.
Re: Burned Out Battery (Alternator) Light Indictor...Major Drain
indycar89 wrote: ↑22 Feb 2021 18:39
Nifty meter in the check panel - remember what/where you found it?
https://www.amazon.com/gp/product/B00YA ... UTF8&psc=1
My check panel came apart easily so installing the meter wasn't difficult.
Where were you able to get the voltage signal from? Inside the Check Panel or ?
Nifty meter in the check panel - remember what/where you found it?
https://www.amazon.com/gp/product/B00YA ... UTF8&psc=1
My check panel came apart easily so installing the meter wasn't difficult.
Where were you able to get the voltage signal from? Inside the Check Panel or ?
Re: Burned Out Battery (Alternator) Light Indictor...Major Drain
A spare bulb is always in my glovebox. However when my light did not come on it was due to to a dead alternator.
Re: Burned Out Battery (Alternator) Light Indictor...Major Drain
by demetk » 24 Feb 2021 23:20
craigb93 wrote: ↑24 Feb 2021 21:40
Where were you able to get the voltage signal from? Inside the Check Panel or ?
by demetk » 24 Feb 2021 23:20
I may have spliced at the check control connector. I could check if needed.
Sp, system voltage. Would be kind of messy to wire for alternator output anyway.
Thank you. -Dick
craigb93 wrote: ↑24 Feb 2021 21:40
Where were you able to get the voltage signal from? Inside the Check Panel or ?
by demetk » 24 Feb 2021 23:20
I may have spliced at the check control connector. I could check if needed.
Sp, system voltage. Would be kind of messy to wire for alternator output anyway.
Thank you. -Dick