Please help with a 2005 Toyota 4Runner Charging System Issue

I am stumped and genuinely need some help. My 2005 Toyota 4Runner has the 4.7 V8 and in the last week or so, the charge indicator light on the dash has been intermittent and then suddenly on always. I started searching around and pulled the batt cables and cleaned the corrosion. The charge light has remained on and when I start it up, it almost gets to operating temp and then lights, radio, heat etc. all begin to shutdown. Then the dash lights up like a Christmas tree and shortly thereafter, the tach drops to zero, the engine sputters and then dies and will not start again until I disconnect batt cables and reconnect. I am in a very precarious situation in life and desperately need this vehicle back on the road ASAP. Please help! Thanks in advance.

How old is the battery? More than likely the alternator is bad. Should be putting out 14.7v when engine is running.

Unsure on the battery. I bought the Runner from an individual a few months ago. And yeah, everything I have researched tracks back to the alternator but, I have got to get this right the first time. Thanks for the feedback!

Then do both. It will save you alot of headaches.

I completely agree with you. Unfortunately, with the mess I am at the moment, it’s difficult to do either. Fortunately, for now, the battery is hanging on.

Good luck. Hope you get it solved quickly.

Thanks and me too.

Hey! Question…I have heard some say to start her up and then disconnect the negative cable and if she quits, it’s the alternator. Others say disconnect the positive cable. Others have said do neither. Your thoughts?

Hey! Question...I have heard some say to start her up and then disconnect the negative cable and if she quits, it's the alternator. Others say disconnect the positive cable. Others have said do neither. Your thoughts?

DON"T DO IT ! That worked for older cars without all the electronics we have now. Way too much risk of damaging something a lot more expensive than an alternator.

Hey @K2010 Bad Idea in my book. Get a memory saver or use an auto parts store that uses one nd free battery installation. I would start with the battery and move up uf needed. Anecdotal evidence I went to an autozone for a new battery for my daughters saturn, and asked if they used a memory saver. They said yes ever since we did not use one on a Honda and had to pay $1200 to replace the brains.

Thanks! That was exactly my thought. I didn’t really expect to find that info in a Toyota forum for this vehicle but, I did. And just wanted feedback.

That sucks Barkydog! The brains have been on my brain at this point.

Your problem might be caused by a worn out brush assembly on the alternator.

To replace the brush assembly all that needs to done is remove the cover on the back of the alternator. And on some Toyota’s, this can be done without removing the alternator from the vehicle.


Thanks Tester. I had been reading up on the brushes. I may be able to do so on vehicle but, it’s a tight fit for sure.

Get a voltmeter:

I wouldn’t own a car without one.

Sweet! Thanks insightful.

Get a cheap multimeter, you can measure the voltage at the battery and the back of the alternator.

My vote is for a cheap voltmeter. That can save you a lot of grief and possibly money expended replacing something that does not need to be replaced.

Until a VOM is procured you might try this. Turn the key to the RUN position (engine not running), and touch the alternator pulley with the tip of a screwdriver or other piece of ferrous metal.
If you feel a magnetic attraction by the pulley then an assumption could be made that the alternator is good. That’s not 100% foolproof but something to kick around until further testing can be done.

As said above, definitely don’t run the engine unless all the battery and alternator connections are solidly connected and configured like they came from the factory. Doing otherwise could prove very expensive to fix.

It sounds like you either have an alternator on the fritz, or maybe you’ll catch a break and it’s just that the belt is loose. Any shop could tell you which. Some big box retail auto parts stores will test the charging system and battery for free. No harm to ask around.

One thing a person can do to get an idea if their alternator is working correctly or not is – do this at night with the car in the driveway, and facing the garage door or a wall or something. Then with the engine warm and idling, turn on the headlights. Note how bright they are. Then turn the key to “off”. As the engine dies you should see a noticeable decrease in headlight brightness. If you do, the alternator is probably working.