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  1. #1
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    Mar 2008
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    Car Gurus - Battery light on 2003 4Runner, ? alternator

    I was hoping a car guru in the collective may have insight into a Toyota 4Runner question.

    I have a 2003 4Runner V8 with 204K miles that I drive daily, have always kept up on oil changes and maintenance and it drives wonderfully so hope to hold onto it as long as I can. Recently, every few weeks when I turn the ignition the battery light on the dash will flash on for a few seconds and then turn off. This always happens when it's raining hard and, while the warning light is on, the power steering is clearly not working, etc. Yesterday I drove through a heavy puddle at night on a 45mph road and the battery warning flashed on for a few seconds while driving, power steering again was off, and then quickly resolved and drove perfect. It clearly has to do something with water

    I took it in to get looked at and the battery's apprently fine, they said it may be the alternator though nothing overtly wrong, replacement for the alternator is pricey relative to the value of the car but would do it given how well the car otherwise drives. Thoughts on the cause/solution? As always, really appreciate the group's expertise.
    Originally Posted by jm2e:
    To be a JONG is no curse in these unfortunate times. 'Tis better that than to be alone.

  2. #2
    Join Date
    Feb 2018
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    58
    I cant speak to the 4runner specifically but I've had an alternator go out and the symptoms sound similar. If it is the alternator, it will continue to get worse and start happening while you are driving and eventually the battery will start needing to be jumped to get moving.

    There may be places near you the will rebuild the alternator for significantly less. That what I had done. They basically replace the brushes and whatever else is needed and it will work like new. So look into that. It may also be easy to replace yourself or buy a friend pizza and beer to do it, depending on the location relative to the engine. The problem with a rebuild is that you will be without your car for a few days while it gets rebuilt.

    Not sure if this is any help, but good luck.

    Sent from my Pixel 2 XL using TGR Forums mobile app

  3. #3
    Join Date
    Mar 2016
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    No Toyota guy here but I'd be checking/re-doing all my main battery connections. Get some dielectric grease. I'd be checking both battery cables, both ends. I'm suspicious of the ground, follow the NEG cable from the terminal to the ground and clean up the ground connection if you can. Sometimes a cable is corroded down inside the insulation and you can't see it, so new cables may be in order, also not cheap (but not the $$ of an alternator) but check the connections first.

    If replacing an alternator, I'd recommend trying to put out the $$ for a NEW alternator. See if Bosch makes one. You apparently have to be quite fucking demanding to get anybody to cough up anything but a re-man'd one. (or, yes, as suggested above, a local shop that rebuilds - I've had bad luck with teh parts store re-man'd ones).

    Also agree to attempt a DIY on it if it is the alternator.

    I had a few go out but once it was done, it was done, not intermittent as you describe. I heard the bearings going bad and then, soon, ran out of juice going down the highway, but by then, the batt is dead, so you case sounds a bit odd in that regard.

    good luck!
    If we're gonna wear uniforms, we should all wear somethin' different!

  4. #4
    Join Date
    Sep 2006
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    3,233
    As per above battery connection is everything and degrades.
    You can buy a $2 wire brush to clean the battery terminal and inside of the connector cable clamp.

    Batteries are a wear item.

    Alternators are cheap in the scheme of auto repair and can usually be done in your driveway in a couple hours.

    As Tuco has learned us a few times, ignition cylinders are more important and finicky than they seem.

  5. #5
    Join Date
    Sep 2011
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    Another vote for connections as the starting point. Wire brush or steel wool first for cleaning. Dialectic grease is your friend. How old is the battery? If it is the alternator then the battery has suffered some abuse and you may want to replace as well.

  6. #6
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    Mar 2008
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    Quote Originally Posted by Orthoski View Post
    Recently, every few weeks when I turn the ignition the battery light on the dash will flash on for a few seconds and then turn off. This always happens when it's raining hard and, while the warning light is on, the power steering is clearly not working, etc. Yesterday I drove through a heavy puddle at night on a 45mph road and the battery warning flashed on for a few seconds while driving, power steering again was off, and then quickly resolved and drove perfect. It clearly has to do something with water
    .
    The engine drives the power steering pump it is a hydraulic pump running off of an accessory drive belt and there is nothing electrical about it BUT the accessory drive also runs the alternator.

    if you are losing the powersteering and the alternator light is going on it sounds to me like the engine is momentarily dying

    you will probably lose power brake effect at the same time ?

    Doesnt that light also goes on when you turn on the ignition but haven't started the engine yet, so in effect the same thing is going on ... the ignition is on but the motor died/is not running ?

    is that one of the toyo's that has recalls for rusting frame ... which could affect grounds

    as for ignition cylinders people who put a lot of shit on their key chain can fuck up the key if not the ignition cylinder
    Lee Lau - xxx-er is the laziest Asian canuck I know

  7. #7
    Join Date
    Oct 2010
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    22
    Check your serpentine belt as well. If the belt is slipping, the alternator won't turn and neither will the power steering pump. It's very unlikely the power steering pump went bad, but the belt driving it could easily be worn out. Getting water splashed on a worn belt or having condensation in the engine compartment from sitting overnight could make it slip enough to lose power in these two areas. I agree with the suggestions to clean up the grounds as well, just a brass brush on the battery terminals and the alternator connection. Do some minor troubleshooting like this before diving in too far. The Toyota 4.7 V8 is a legendary engine, and it's more likely to be something minor.

  8. #8
    Join Date
    Mar 2008
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    272
    Thanks so much, everyone. I went as far as to take it to a dealership for my last oil change figuring they could at least diagnose it and they said the battery was good, they suggested the alternator but said it wasn't worth replacing yet. It does have something to do with water - the few times it happened when starting the car was during a downpour, but the engine actually started pretty well after an initial pause. It again happened with a big splash of water from the undercarriage. To XXX-er's point, the feeling of depressing the brake pedal changes, too, now that I think about it, so if that points to alternator then probably worth having it replaced. Falcon3, would they look at the serpentine belt at the same time? I drive at crazy hours in bad weather so the last thing I need is to get stuck, but I love that 4.7 V8 and am not as excited about the newer 4Runners.

    The 2003 4Runner was never formally recalled, but it sits on the same frame as the Tacoma of those years that were recalled. They looked at the frame and not rusted through yet.

    Thanks everyone. You make me want to have cooler friends - my friends know how to do stuff like replace someone's kidney or joints but not an alternator....
    Originally Posted by jm2e:
    To be a JONG is no curse in these unfortunate times. 'Tis better that than to be alone.

  9. #9
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    Good info above - I'll add that when replacing the serpentine belt, replace the tensioner too.
    Quote Originally Posted by powder11 View Post
    if you have to resort to taking advice from the nitwits on this forum, then you're doomed.

  10. #10
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    Another vote for belts.. Slip more when wet. Had a charging and power steering issue. Replacing the belts resolved both.
    Go that way really REALLY fast. If something gets in your way, TURN!

  11. #11
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    Quote Originally Posted by Orthoski View Post
    . It again happened with a big splash of water from the undercarriage. To XXX-er's point, the feeling of depressing the brake pedal changes, too, now that I think about it, so if that points to alternator then probably worth having it replaced. ....
    No losing power brake action is pointing to the engine dying, becuz the power brake boost runs off engine vacuum so if the engine is dies even momentarily it will also affect the power brakes

    if the brakes were ok but just the alternator light went on and the power steering quit working I would suspect the accessory belt driving these, I think its one big serpentine belt driving everything on most newer cars

    It could be either of those but not an alternator cuz when it quits charging the light goes on/stays on but the engine will still run on whatever juice is in the battery for quite a long time until you use it all up, I rented an old Nova police special from rent-a-wreck for a 6 hr roadtrip, when the the alternator light went on, I still got it home the engine still ran for probably 1.5 hrs, the head lights got very dim, so dim I drove over an unseen curb in the middle of the highway

    good thing it had the police special heavy duty suspension
    Lee Lau - xxx-er is the laziest Asian canuck I know

  12. #12
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    Car Gurus - Battery light on 2003 4Runner, ? alternator

    An auto parts store can test the alternator. I have a 2005 4Runner and literally had the same dash light come on two weeks ago. Got it tested and the alternator was bad. Replaced it last weekend and everything is back to working perfect. If you have 204k miles, you’ve gotten a lot of life out of that alternator as mine went bad at 160k.
    In constant pursuit of the perfect slarve...

  13. #13
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    Feb 2006
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    I'd definitely suspect the belt and possibly as pointed out change the tensioner also (BUT NO 4Runner expert either). If the Alternator is that expensive that you do not want to do it, then belt and tensioner is first step probably at a lower price. Alternators can be tested too, ODBI II diagnostics on it when the car is moving to monitor the voltage. And you state it is too early to do the alternator, if it is the alternator, it is not too early for 2 main reasons in my opinion. First you state you also loose power steering. Nothing worst than having a hard time making a turn due to no power steering and ending up having to prepare to muscle the wheel around, or if not able to do that, possibly running off the road or into the other lane, or having an accident because the turn was not made when the voltage dips. The other reason is if the alternator is starting to go, never know when it will go out completely and end up stranded out somewhere not able to drive it because the battery is drained and not charging while the engine is running.

    The belt and tensioner should be about $50 or so in parts (more if you have a garage do the work but still should not be that much higher expense). The Alternator on line in remanufactured is about 3 times that (but there is a core exchange charge and if you return the defective unit you pull out of the vehicle then you get some money back too) for the part on line, or 6 times that if you want brand new (and why would you go new on a 2003 vehicle really in my opinion)...
    Last edited by RShea; 11-10-2018 at 11:30 PM.

  14. #14
    Join Date
    Oct 2010
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    22
    Quote Originally Posted by XXX-er View Post
    No losing power brake action is pointing to the engine dying, becuz the power brake boost runs off engine vacuum so if the engine is dies even momentarily it will also affect the power brakes
    I want to say the 4th gen 4runners all run off electric brake boosters, not vacuum (2008 4runner owner here). I'd be very surprised if the engine is dying and causing this problem. I think the problem still comes down to a combination of the alternator and the belt system. A private shop should be able to diagnose/fix this for pretty reasonable. I'd get some quotes and do some review searches of shops. I would likely go private before dealer. Yes, they should have checked the belt when you asked them to trouble shoot your problem, but it's likely they just put a tester on the battery and did a charge/load test on it and didn't go any further. As El Chupacabra pointed out, it could also be a bad tensioner that doesn't allow the belt to be fully engaged on the pulleys and slips. Maybe try asking this question over at toyota4runner.com, those guys are very helpful, and at the least, could help you find a good mechanic in your area.

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