ANOTHER battery light question !!!!
- Thread starter Rsbhunter
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spartacus
Senior Member
I don't have a 4th Gen. Assumming battery terminals and alternator wire and ground connections are clean and tight. Also the beltgood. Check that ground is good. Test the ohms between the negative terminal and chasis also between battery negative and alternator cage. The reading should be very close to zero ohms. Good luck
Thanks, I did check belt, no cracking at all, sanded ground on fender to shiny metal, and lug. Will check the ohms, im at a loss, I checked, AND replaced every fuse related to alt, batt, ign, . I am starting to think about a $300.00 plus Toyota Alt. Everything is working/charging, but it bothers me that I won't know IF something fails.....is there anyway to unplug the alt plug, energize the grey wire with 12 volts with the key on to see if the light goes out? rsbhunter
Seymore Butts
New member
Make sure that you have a long sample of alt voltage in case it is fluctuating and triggering the light with low voltage.
spartacus
Senior Member
Is the grey wire the lamp wire from the alternator to the battery warning light. The simplest way to verify the lamp output from the alternator is not functioning is by replacing the alternator. To trouble shoot gets a little more complicated. Will have to ground the battery warning lamp and see if it goes out when energized. Next step will be complicated and would require access to the lamp output wire with a volt meter attached. check the lamp output wire from the alternator with the motor running to verify that it has 12 volts. It could be that your alternator is working properly but the lamp output from the alt is not good.
3 wires on alt plug?
Just went out to check grey wire on alt plug....first, there are only 3 wires going into plug, and their all molded side by side ....harness has never been messed with......this started after not driving for about a week...went and started, batt light and all the abs, Trac control, etc lights on right side of speedometer were on....checked, abs/ speed sensor, wire was pulled apart at the upper bracket of upper control arm!!!!! Checked batt...11.78, bought new 27F battery....checked alt 12.8-9 volts on start up...replaced alt with rebuilt Remy brand....now, 12. 8 at batt, 14.2 running.....im about ready to give up. I'm older, don't mistreat, off road, etc....all happened sitting in my driveway!!!!
Just went out to check grey wire on alt plug....first, there are only 3 wires going into plug, and their all molded side by side ....harness has never been messed with......this started after not driving for about a week...went and started, batt light and all the abs, Trac control, etc lights on right side of speedometer were on....checked, abs/ speed sensor, wire was pulled apart at the upper bracket of upper control arm!!!!! Checked batt...11.78, bought new 27F battery....checked alt 12.8-9 volts on start up...replaced alt with rebuilt Remy brand....now, 12. 8 at batt, 14.2 running.....im about ready to give up. I'm older, don't mistreat, off road, etc....all happened sitting in my driveway!!!!
inscarguy
Member
The diode might be bad in the alt. That is what triggers the lamp. When I was on the parts side I lost count of how many good charging alternators we sent back to the rebuilders because of a bad diode. Most rebuilders never check them. The alternators charge like their supposed to but the diode fails. I would get a used OEM alternator from a salvage yard and try it.
Agree!!!!
I'm about to look into that solution. I live in a small town, not a great selection of used parts....what would be the best source for another rebuilt QUALITY alternator? Dealer ? Not a WAH, but I'm 67 years old, and I'm tired of messing with this, I'll do it again, but would like the best chance to get a functioning alternator...Thanks for all the help, this solution seems to have the highest possibility of success so far.....
I'm about to look into that solution. I live in a small town, not a great selection of used parts....what would be the best source for another rebuilt QUALITY alternator? Dealer ? Not a WAH, but I'm 67 years old, and I'm tired of messing with this, I'll do it again, but would like the best chance to get a functioning alternator...Thanks for all the help, this solution seems to have the highest possibility of success so far.....
MikeinNH67
Senior Member
I only buy Denso remans (sometimes Rockauto has them) or used ones. The chain store remans are junk for starters and alternators from what I see. Depending on timing I'll get used from an ebay junk yard or if in a rush a local junk yard. If e-bay, preferably a Southern one of a low-ish mile vehicle. Look for the Toyota sticker on them.
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Diode test
Ok, took the multimeter out, engine running, lowest AC voltage range, battery positive and negative = 0 volts.....does this mean anything, or is it a separate diode that controls the batt light? Thanks guys, I know I beat this to death, but I really am ocd, and its aggravating! rsbhunter
Ok, took the multimeter out, engine running, lowest AC voltage range, battery positive and negative = 0 volts.....does this mean anything, or is it a separate diode that controls the batt light? Thanks guys, I know I beat this to death, but I really am ocd, and its aggravating! rsbhunter
This alt was a "Remy"
I bought this one from Rock Auto, (Remy)figured it was decent, but there's always one that gets through....are Denso's really reliable? I'll spend the money to fix it, just don't want to throw good money after bad!!! Thanks again
I bought this one from Rock Auto, (Remy)figured it was decent, but there's always one that gets through....are Denso's really reliable? I'll spend the money to fix it, just don't want to throw good money after bad!!! Thanks again
MikeinNH67
Senior Member
Denso (formally Nippondenso) is the OEM manufacturer. Do you still have your old alternator? If so maybe have a local parts store test it to make sure it was bad? Without a 3rd known good one to try it's kinda tough. Most places don't accept a return on electrical components.
Old alternator
No, had to return to RA for $70.00 core. I tested old one on 4R, showed 12+ v , took to advanced A P ,off vehicle, tested bad there..... Ordered reman from RA.....and here we are!!! Thanks for all the info....Found a Denso rebuilt at Summit Racing for $122.00 with free shipping not to bad if it fixes it!!!! But I'm waiting for the fairy's pixie dust to make it all better.....I WISH!
No, had to return to RA for $70.00 core. I tested old one on 4R, showed 12+ v , took to advanced A P ,off vehicle, tested bad there..... Ordered reman from RA.....and here we are!!! Thanks for all the info....Found a Denso rebuilt at Summit Racing for $122.00 with free shipping not to bad if it fixes it!!!! But I'm waiting for the fairy's pixie dust to make it all better.....I WISH!
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MikeinNH67
Senior Member
LOL, I never seem to have any working pixie dust. So the old tested bad, maybe have them test this one too? Good luck!
AuSeeker
Elite Member
AC is "Alternating Current" which is what you have in your house, for the most part all automotive voltage is DC "Direct Current", there's an exception to this and it's when you have a 12 volt DC to 120 Volt Ac "power inverter" to run a 120 volts AC circuit to power 120 Volt AC items/appliances in your vehicle.
MikeinNH67
Senior Member
I assumed he had it on AC to verify he doesn't have a bad diode. Seems if there's one bad you will get some AC voltage showing where it should be 0.
Step 4:
https://www.truckofmine.com/how-to-test-an-alternator-diode/
