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Discussion Starter #1 (Edited)
Day one, The rav stopped one day in a very weird way in the middle of an intersection. Dash lights when crazy throwing all possible errors, radio died, power steering died, and all power eventually stopped working. I jumped it and was able to drive most of the way home. So I figured it has to be the alternator or battery. We changed the alternator and the store said the battery was good.

Day two, Drove around for about 2 hours and same deal. This time we figure, lets go as far as we can without shutting off the ignition. the car got about 10 miles and as we got further is acted like the alternator just was not charging the battery. Then I figured, turn the AC off. whenm I did that it restored all operations and we got 10 more miles. Then, gradually slowed down until the car could not charge the battery. So We took back the battery and demanded a replacement.

Day tree, Drove around most of the day without issues, and as we pulled in to our home, it stared back up again. Lucky we made it up but I'm out of ideas here? What is going on ?

Oh, I did check the 80 amp fuse. Looks good.
 

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There's very little diagnostic info in your post. Until some voltage reading are made we, like you, can only guess what's wrong.
 

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Day one.......So I figured it has to be the alternator or battery. We changed the alternator and the store said the battery was good.
Rule #1
You shouldn't fix/replace anything unless it's broke. To determine if the alternator is working, measure the battery voltage when the engine is running. A voltage of 13.8-14.8 = good alternator. Less than that = bad alternator.

Day two, acted like the alternator just was not charging the battery. Then I figured, turn the AC off. whenm I did that it restored all operations and we got 10 more miles. Then, gradually slowed down until the car could not charge the battery. So We took back the battery and demanded a replacement.
It sounds like the alternator is not charging the battery, and the battery, (which had been tested and shown to be good), was doing an excellent job of providing energy to run the entire electrical system. As the battery voltage began to get low, you turned off the unnecessary load, the battery voltage increased slightly (E=I*R) and the engine ran better.

I think purchasing a new battery was a waste of time.

I expect the alternator is not producing proper output. This may not be caused by a defective alternator, but a loose or corroded cable, or a blown fuse . You mentioned in the other thread, that as an EE, you have access to test equipment. It's time to get out a voltmeter and check the alternator output.

Oh, I did check the 80 amp fuse. Looks good.
What fuse was that? My first suspects would be the ALT fuse, which is 120A without the tow package and 140A with the tow package.
 

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Discussion Starter #4
Sorry left this post without details, been working the issue for a bit now. I realize it was vague and I meant to get back to the post but cars have a way of eating up time. I'll try to answer the questions here but most importantly I finally found a problem I can grasp on to.

So after a the new battery and alternator were in I had a chance to measure the battery and saw it was around 12.5 and dropping with the car on. If I jump the car the voltage will go up but when I release the jump it starts to drop and continues to drop till the car dies. I then looked for as much of the obvious as I could and poked around on the net a bit. A few things I have already done are.



1) Fuse for the alternator is ok, I found a ref. to a 80 amp fuse on line but I checked the 3 large fuses including the 120.
2) Looks like the battery main ground to chassis was not connected. I did find where it goes and connected it.
3) The battery holds a good charge, it was under warranty so we got a new one for no cost.
4) The alternator was replace and but only a presumption that its good at this point (could be doa).
5) I looked for something that was shorted and not tripping a fuse causing a drain.
6) tried to pull a few fuses to see what is draining the battery.
7) I turned everything off but the engine and the battery still drains. (this includes removing the radio and ICP, figure it could be an internal short)
8) When the car is off the battery seems not to drain, or at least not at a rate that implies the problem exist when the car is off.

Ok questions.
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Dr. Dyno, yup my apologize's, just wanted to get the post started I planed to add more but didn't have the time.

Rickl
Rule #1 - Yeah I get that, my fault for not including more of that info. I knew something was broke and the battery was under warranty, so figure what the heck. When they tested it to be ok We just figure it would be best to get a new alternator and the cost was not an issue for us and to me it just sounded like an alternator issue. I think most people in my position would have agreed.


Based on the description I left above I would have agreed with your thinking (as why I bought an alternator). And maybe the new alternator is bad but doubtful. Either way I'll test it next.
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Aside from my issue, here is what mystifies me a bit. If the alt. has a 120A max output then whatever is draining the battery must be pulling near 90 amps when idle and no accessories are on, no? Because, the alt. is giving up a few amperes to other equipment but it should support most equipment and a demand of 120 amps. So what in the heck besides a short that is not fused would draw that much current? And would I not smell or see signs of a short like that?
 

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I had a chance to measure the battery and saw it was around 12.5 and dropping with the car on. If I jump the car the voltage will go up but when I release the jump it starts to drop and continues to drop till the car dies. .................
8) When the car is off the battery seems not to drain, or at least not at a rate that implies the problem exist when the car is off.
Since the alternator is not putting out voltage in the 13.8-14.8 volt range, it is not working. If the alternator is not working , the battery will continue to drop in voltage as the current is drawn from it.

You seem surprised that the voltage does not drop when the car is off, but does drop when the engine is running. That is simple to explain. When the car is off the battery only supplies minimum current to maintain the radio memories and the clock, and the ECMs are in standby mode. When the engine is running, now the ECMs are actually running at full load. They are providing power to fire the injectors, run the fuel pump, etc. The dash lights are also on, the radiator fan is running, and probably several other things.

here is what mystifies me a bit. If the alt. has a 120A max output then whatever is draining the battery must be pulling near 90 amps when idle and no accessories are on, no? Because, the alt. is giving up a few amperes to other equipment but it should support most equipment and a demand of 120 amps. So what in the heck besides a short that is not fused would draw that much current? And would I not smell or see signs of a short like that?
Once again, your alternator is not outputting any power. When the engine is running, your RAV is getting all of it's electrical needs from the battery causing it to drop in voltage.

Either your alternator was DOA, or one of the circuits that control charging rate is defective. That could include the "Battery Current Sensor" which is mounted on one of the battery posts. Make sure that the small electrical connector has not fallen off this sensor. Does your "Charge Warning" idiot light come on when the engine is running?. Does it come on during the lamp test?
 

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Discussion Starter #6
You seem surprised that the voltage does not drop when the car is off, but does drop when the engine is running. That is simple to explain. When the car is off the battery only supplies minimum current to maintain the radio memories and the clock, and the ECMs are in standby mode. When the engine is running, now the ECMs are actually running at full load. They are providing power to fire the injectors, run the fuel pump, etc. The dash lights are also on, the radiator fan is running, and probably several other things.
No that's wrong, you didn't read that right. "When the car is off the battery seems not to drain, or at least not at a rate that implies the problem exist when the car is off." My pointing being it does not drain at that same rate. Yes all batteries drain I realizing that but not with in a few hours. When the car is running it will die within 4 hours and the car can be left for days before it does. Either way, the condition is most prevalent during running so I'm making the guess that it is ignition based circuitry.

Once again, your alternator is not outputting any power.
Right but again I wrote that based off the fact that I presumed a new alternator to be good.

So aside from the dismantlement of my post your comment here really is starting to help me.

That could include the "Battery Current Sensor" which is mounted on one of the battery posts. Make sure that the small electrical connector has not fallen off this sensor. Does your "Charge Warning" idiot light come on when the engine is running?. Does it come on during the lamp test?
Battery light is not coming on no... It does light up when the car comes on. As I mentioned I'll have the alternator tested and report back. I'll also inspect this Current Sensor, thx for that. I read that in some cases it's in the ECU (found that hard to believe) and that all alternators will have regulators built on to them now(that I figured). So I was hopping to find another component. If you could provide any pictures that will help me know what wire form the alternator goes to the battery that would also help. I'd like to check that as-well.

BTW: the tidbit about the alternator running and showing 13.8-14.8 volt range was very helpful to me. I often wondered that, so as you pretty much said that would still show even if I had a short in the system. Thus, the alternator is not connect right or bad ( and only one of the two are possible).
 

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No that's wrong, you didn't read that right. "When the car is off the battery seems not to drain,When the car is running it will die within 4 hours and the car can be left for days before it does.
I think that perhaps you didn't read my post right! I explained how a vehicle requires more electrical current when it is running, than it requires when it is turned off. That would cause the battery to deplete its charge much faster ( say 4 hours) compared to days when the engine is not running. Remember that your alternator is not contributing anything. Your engine is running on battery reserve only.

Battery light is not coming on no... It does light up when the car comes on.
In that case I suggest testing the Gauge1 fuse (10A), this fuse also powers your backup-lights, so check if those are working.

Also test the Gauge2 fuse (7.5A). This fuse also runs the instrument panel and many of the idiot lights.

Both of these fuses are located in the interior fuse panel located near the drivers left knee. See image.
 

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Discussion Starter #8
I think that perhaps you didn't read my post right!
All I meant is that what you said in your last post is what I said, so I agree to agree then.

Anyways, you have been most helpful and I thank you. Problem was the fuse ( Gauge1) as you pointed out.
 

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Anyways, you have been most helpful and I thank you. Problem was the fuse ( Gauge1) as you pointed out.
Glad you got it working. Now you have a new fuse, alternator, and battery.
 

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Pretty expensive fuse, eh?
 

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From post 1:
... Then, gradually slowed down until the car could not charge the battery. So We took back the battery and demanded a replacement.
:wall Guess he should have demanded a new 10A fuse instead.
 

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I already explained rule #1, "don't fix/replace anything unless it's broke.".

I will introduce you to rule #2." if something breaks don't look for something complicated, just check the last thing you touched"

In this case the last thing you touched was hooking up your camera to the backup lights. It would seem that in doing so you blew the fuse that powers the backup lights, and also lets your alternator produce output current.

These simple rules have simplified my life many, many, times.
 

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All I meant is that what you said in your last post is what I said, so I agree to agree then.

Anyways, you have been most helpful and I thank you. Problem was the fuse ( Gauge1) as you pointed out.
Glad you're good to go! I always learn a lot from these threads.
 

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I already explained rule #1, "don't fix/replace anything unless it's broke.".

I will introduce you to rule #2." if something breaks don't look for something complicated, just check the last thing you touched"

In this case the last thing you touched was hooking up your camera to the backup lights. It would seem that in doing so you blew the fuse that powers the backup lights, and also lets your alternator produce output current.

These simple rules have simplified my life many, many, times.
I know this is an old post but I'm having the same isues. In our case I believe the alternator had been going out for some time, Like you I figured don't fix it till its broke. The power steeing (electric) went out and dash lights flashed. and the wife told me it had been whining for a couple of days. Got it home battery was below 9vts, I had an extra battery (wifes wrecked car) to put in. Tested the alternator with cale off it diied under a load, plus it was whining so I knew the bearing(s) were bad so I bought a new alternator and just put it in. Well at least the whining stopped. However when I pull the battery cable and put it under a good load it will die, I don't think I am anywhere near 100 amps. The following are some observations and test.

1. Battery is good (nearly new), above 12.6vts (resting voltage).
2. When running voltage is all over the place but not over14Vts with or without a load.
3. The running lights will flicker with the battery cable disconnected, even with minimum load.
4. It was running (cable off) and lights on but would die when the heater came on, now it dies after a few moments with just the lights on.
5. Alternator voltage is all over the place with the battery wire disconnected from the alternator. (not sure which wire is the field so I left the plug connected.
6. Backup lights are working.
7. All panel lights appear to be working.
8. I have about 1/4 amp draw with the key off. This seems a bit high, but not too unreasonable.
9. I had my wife take it to Les schwab for confirmation. She thinks they said when under a load that it was reading 12 vts, I'm not sure if the battery was connected. I tried to repeat the test but my meters are digital so I couldn't get a accurate reading. I will test it again with my analog meter if I can find it.

My suspesions are that I got a bad alternator, but it can be a controler, sensor, or even an internal regulator. I'm just not sure at this point. Is there anything else that I can take a look at? The flickering lights would seem to indicate a voltage control issue, I'm just not sure where to look. I did see a small rectangular box with a plug on the negative terminal connector would this be the voltage sensor? and is there a way to test it? just for your info I removed the ground side of the battery for testing, if it makes a difference. Thanks Mike
 

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I haven't even read your whole post but running w/o the battery connected is NEVER a good idea. It acts as a very large capacitor to stabilize the voltage. W/o it spikes and variances are to be expected. I just hope you didn't damage any electronics.
 

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I haven't even read your whole post but running w/o the battery connected is NEVER a good idea. It acts as a very large capacitor to stabilize the voltage. W/o it spikes and variances are to be expected. I just hope you didn't damage any electronics.
It is never a good ideal to run 12vt appliances above 14.5vts as you pointed out it can damage or prematurely shorten life expectancy of the appliance such as headlights and the battery does act as a capacitor filtering voltage spikes.
I'm not an expert by any means but I have run 12vt systems Radios and lights using 14vt batteries (7 - 2vt cells), sometimes with modified chargers for a long time. this as you might guess simulates a battery at near peak voltage 14.5 vts with a charge still being applied. What this does is increase battery life and performance under load conditions that is a a 12vt battery under a heavy load can drop to 10.5 vts before being damaged when you add an extra 2 vts this load voltage increases to about 12- 12.5 volts. Ever notice when you crank an engine with the lights on the lights will dim. not as noticeable on a 14vt system.

I don't run a 14vt system in my car! but an off grid system for a home you bet.
As stated I'm no expert by any means, but typocally when a person has a charging issue its not overcharging. Yes spikes are a concern, but an alternator system is designed not to exceed certian voltage typocally about 15 - 15.5vts and perfereably 14.5 - 14.75vts. If a system is spiking or overcharging the batteries ability to filter it will have diminished by the time you notice the problem therefore damaging componants. Smart chargers and car charging systems are designed to sence voltages and shut down, that why you can't run equipment using a charger (must use a converter). Yes unfortunatly there is always a risk. I like what Ricki said don't fix it if it isn't broke, I say this run it till it breaks sometimes its the least costly way to find a problem. Some people throw money at the problem till it goes away.

In my 50+ years of backyard mechanicing. My first charging test is disconnecting the battery post while engine is running I've never caused extra damage that I am aware of. I don't have a $10,000 scanner to analyse my car and talk about throwing money at it why don't I take it to the shop? because they want $1000 to fix it when the part cost $100 and 1/2 hr of work thats $1800/hr sure I can afford it on a $15/hr wage. I had a shop teacher once we had every piece of equipment we ever needed, he said that we don't have this equipment at home so we needed to know how to fix it without the equipment first before he would allow us to use the equipment, he was an great teacher. Have you ever pulled a spark plug wire to find out which cylinder has a miss in it? Its kind of like parking a car on a hole in the tire it's only a means to attempt to slow down the leak so you can get to where you can fix it, It doesn't fix the problem.Sometimes you just got to do what you got to do not everyone is a master mechanic.

Even a master mechanic needs advice once in a while. Making fun of someone or picking them apart for trying is a good thing? "Pretty expensive fuse, eh?" "Guess he should have demanded a new 10A fuse instead." One thing I've learned in 50+ years all knowlege is is passed on we are all ignorant till we are taught or have learned on our own.ulao's education came at a cost at least he did something. He came here for advice and he got it thats great! I did notice that the ones who did not offer help or advice were the ones who poked fun at him and one was a moderator. I like Ricki he was patiant gave sound advice and allowed his student to learn the hard way he may have smiled at the mistakes but probably because he made a few of those mistakes himself as he was learning.

As a man it's hard to ask for help, then to be pick on him when you do ask for help That's just wonge. Something else I've learned the more someone pokes fun at someone elses ignorance the less that person actually does know. A master teacher does not taunt others for what they lack in knowledge or ability, but conciders it an honor and a privelige when they are able help and teach others what they know.

I guess when a man has nothing to offer or teach they feel better about their own short commings by pointing out someone elses lack of knowedge and understnding. We have all been there I've been on both sides of the argument. Perhaps the reason men are reluctant to ask for help (directions), is because when they do there is some one who will try to make them look small.
 

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Don't know whether you feel that Dr. Dyno was attempting to make you "look small" in that lengthy post but he is both an electrical engineer and a mechanical expert who has helped countless owners over the years, both on and off this forum.
 
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Even YouTube's Scotty Kilmer (who has 50+ years of auto repair experience) says to NEVER disconnect the battery when the engine is running on modern cars. The ECM or other computer modules can be damaged.
 
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