Effect Of Burned-out Charging Bulb

[ARCHINSTL]

Re: car is killing batteries, no interior battery dummy light on - Thread begun by mountaindude.
4wdEconoBox » 22 Sep 2016 09:57 pm

I would probably lean more towards the burned out charging bulb, just because you said that it doesn't come on anymore. If that light gets blown, then your alternator doesn't get "excited" and that means your alternator won't charge the battery at all. Next chance you get, check your battery voltage with the engine off using a digital voltmeter on the terminals of the battery and see what your voltage is. Then start the car and check the battery voltage again, and if the voltage is the same or lower than the 1st number you got then the alternator isn't charging and more than likely its a blown charging bulb. You may have already known how to do all of that already, but I didn't know your wrenching level, so I figured it wouldn't hurt to explain it the most detailed that I could haha. Good luck!

Preceding added by ARCHINSTL to the Repair Guides Forum, as I think this is an important bit of information.
Who knew the cluster bulb could have such an effect on the charging system?

[helipilot77]

Yeah that is something I learned when troubleshooting charging problems in my 4Runner. I had installed an LED in the dash for the charge light and it wasn't creating enough draw to excite the rectifier.

[TaosTertel]

Hey there. So my charge light came on the other day after a pretty rough dirt road and now my battery isn't charging at all. Brand new battery. Wondering if there could be a loose connection somewhere or if I just need a new alternator but the fact that it was after the washboard road makes me think there's some loose connection...

[dlb]

Do you have a volt meter? Just put it on the battery when the engine is off and when it's running, should be above 12.5 when engine is off and around 13.5 when it's running. If it's not, inspect all the connections and make sure they are snug and corrosion-free. If that all checks out, you probably need a new alternator.

[TaosTertel]

Figured. Lost my multimeter in the last move but I'm pretty sure it's the alternator after a little more problem solving so I've got one on the way. Also thaks for the specs

[Petros]

quick alternator test: easiest at night, turn on the head lights with the engine off (pointing at a wall or garage door is best), than start the engine and observe the brightness of the head lights. they will get noticeably brighter as you rev up the engine.

if it is not charging, there could be several causes: check the battery terminals are clean and tight, check the ground strap is not corroded, and is also tight at the body end. It could be a bad battery too, that will not hold a charge (shorted cell). Most places that sell car batteries usually will test your system for free (becasue they want to sell you a new battery). Many auto parts stores will test your alternator for free if you remove it and bring it to them, they have an alternator tester.

Also, realize that you can have a short in the indicator light system that shows as if it is not charging, the light is on, but it is charging fine. mine is doing that now, I have been driving it for six months that way, and still have not sorted out the cause.