Possible Alternator Problem

Shaymer · 02-06-2007, 06:31 AM

About 3 weeks ago, my Battery Check light came on. Since the battery is only a few months old, I figured it was a short or a bad connection.

A few days ago, my radio died, wipers got slow.... (typical sign alternator is going.) I figured I had enough juice to get home, but the truck died on the road. I pulled it over and got a ride home.

I went back the next morning with a new alternator, but it fired right up. When I checked the battery, I noticed that half of the neg. battery terminal clamp had broken off. (it looked like a horseshoe instead of a donut). When I pulled it off, the truck kept running.... which means the alternator was OK.

Thinking that this was the problem, I replaced the terminal cables, checked all the fuses, and checked the tightness of the belts.

Now, when I start the truck, the battery light sometimes comes on, sometimes doesn't. Sometimes comes on while driving, and sometimes goes OFF while driving. Sometimes when I pull the neg. battery cable off, the truck shuts off, but sometimes it stays on. Last night while I was going to work, the instruments started failing again, but when I left work, everything was fine and the check battery light stayed off.

OK, I think its probably an alternator problem, but I want to be sure before I spend $100 on a new one, especially since its in an odd location and will be a pain to replace.

Thanks,
Shamus

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1994runner · 02-06-2007, 06:36 AM

Definately sounds like the alternator is at the end of it's days. While the alternator is a pain to get to, better than being stranded somewhere.

Tdubbs05 · 02-06-2007, 08:22 AM

sounds like you might have the same kind of issue that I had. check out this thread: http://www.yotatech.com/showthread.php?t=103311

i ended up replacing the alternator thinking it was the prob but luckily it wasn't. I ended up giving it over to a toyota shop with a detailed description and they had it fixed in a hour. turns out it was an efi circuit issue that somehow wasn't allowing the alternator to charge the battery. weird stuff... hope that helps.

MMA_Alex · 02-06-2007, 08:25 AM

You shouldn't pull the battery cables as it can damage the computer. The battery helps regulate the voltage.

A lot of autoparts stores will test the alternator for you if you bring it in. I would also check the resistance of the batt cables to see if they're in good shape or not

Shaymer · 02-06-2007, 08:29 AM

Yeah, that sounds like my issue. I was reading the shop manual and it mentioned something about checking the 'fusable links' too. Not sure what those are, but behind the fuse box in the engine compartment is an EFI fuse. It looks good though.

yotaknows · 02-06-2007, 08:30 AM

I just had alt and brake light come on. I took the alt off and checked the brushes..ok. So I took the ground cables off and replaced the ends cleaned both the engine and chassis connection and it took care of the problem. Food for thought.

Tdubbs05 · 02-06-2007, 10:08 AM

i believe that the only thing that happens when you unhook the battery is the computer resets, so it's not really a bad thing. definitely get that alternator tested and hopefully that'll narrow down the problem a little more.

Robrt32 · 02-06-2007, 04:10 PM

I had alt problems on my 92 , I done a little mod work on my brackets and a chevy ,ac delco of about a 85 model and run a wire from it to the pos on the bat. this was 4 years ago , I have had no more trouble .....just a thought for someone that might be poor like me.. The ac delco is 50 60 bucks cheaper

MMA_Alex · 02-06-2007, 04:57 PM

ac delco *shudder*...

when the truck is running the battery regulates the voltage, and smoothes it out. It's not as much of a problem because of the voltage regulator built into the alt, but I still wouldn't risk it because if you fry the comp its not exactly $20 down at autozone to replace it.

^VooDoo^ · 02-06-2007, 08:45 PM

No, The battery is only there to start the engine and keep memory for the ECU, clock and radio, Once the engine is started there should be no need for the battery at all, The internal regulator should do the work or its bad.
Pulling the neg terminal off while its running is one of the easyest ways to check for bad alt, But also turn on other accesories like AC or highbeams.
Remember aftermarket equipment like lights, winch and amps are not in the origanal design concept, So the size of the alternator output is was only intended for the factory equipment.

This has not changes since the first alternator/regulators were installed.

Robrt32 · 02-07-2007, 07:36 AM

Quote:

Originally Posted by MMA_Alex

ac delco *shudder*...

when the truck is running the battery regulates the voltage, and smoothes it out. It's not as much of a problem because of the voltage regulator built into the alt, but I still wouldn't risk it because if you fry the comp its not exactly $20 down at autozone to replace it.

To each his own, I have put the delco's on Fords Dodge Nisson and Toy., It may not work on the newer model trucks. Ive always had older rides and its saved me money numerous times.

02-06-2007, 08:22 AM	#3 (permalink)
Tdubbs05 Registered User Join Date: Jul 2006 Location: Los Altos, CA (Flagstaff, AZ for college) Posts: 338	sounds like you might have the same kind of issue that I had. check out this thread: http://www.yotatech.com/showthread.php?t=103311 i ended up replacing the alternator thinking it was the prob but luckily it wasn't. I ended up giving it over to a toyota shop with a detailed description and they had it fixed in a hour. turns out it was an efi circuit issue that somehow wasn't allowing the alternator to charge the battery. weird stuff... hope that helps. __________________ Tim ___________________________________________ 1994 4Runner \| 3.slow Auto \| 265/75/16 Nitto Terra Grappler's \| Bilsteins \| Downey HD Kit \| ARB Bumper \| Warn M8000 \| 2 Lightforce 170's on the ARB \| Roof Rack w/ Checker HID's \|

02-06-2007, 10:08 AM	#7 (permalink)
Tdubbs05 Registered User Join Date: Jul 2006 Location: Los Altos, CA (Flagstaff, AZ for college) Posts: 338	i believe that the only thing that happens when you unhook the battery is the computer resets, so it's not really a bad thing. definitely get that alternator tested and hopefully that'll narrow down the problem a little more. __________________ Tim ___________________________________________ 1994 4Runner \| 3.slow Auto \| 265/75/16 Nitto Terra Grappler's \| Bilsteins \| Downey HD Kit \| ARB Bumper \| Warn M8000 \| 2 Lightforce 170's on the ARB \| Roof Rack w/ Checker HID's \|

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02-06-2007, 06:36 AM	#2 (permalink)
1994runner Registered User Join Date: Jan 2007 Location: Eastern Iowa Posts: 90	Definately sounds like the alternator is at the end of it's days. While the alternator is a pain to get to, better than being stranded somewhere.

02-06-2007, 08:25 AM	#4 (permalink)
MMA_Alex Registered User Join Date: Apr 2006 Location: Downeast, ME/Rochester, NY Posts: 1,421	You shouldn't pull the battery cables as it can damage the computer. The battery helps regulate the voltage. A lot of autoparts stores will test the alternator for you if you bring it in. I would also check the resistance of the batt cables to see if they're in good shape or not

02-06-2007, 08:29 AM	#5 (permalink)
Shaymer Registered User Join Date: Dec 2006 Posts: 4	Yeah, that sounds like my issue. I was reading the shop manual and it mentioned something about checking the 'fusable links' too. Not sure what those are, but behind the fuse box in the engine compartment is an EFI fuse. It looks good though.

02-06-2007, 08:30 AM	#6 (permalink)
yotaknows Registered User Join Date: Mar 2006 Posts: 61	I just had alt and brake light come on. I took the alt off and checked the brushes..ok. So I took the ground cables off and replaced the ends cleaned both the engine and chassis connection and it took care of the problem. Food for thought.

02-06-2007, 04:10 PM	#8 (permalink)
Robrt32 Registered User Join Date: Jan 2007 Location: Mississippi Posts: 413	I had alt problems on my 92 , I done a little mod work on my brackets and a chevy ,ac delco of about a 85 model and run a wire from it to the pos on the bat. this was 4 years ago , I have had no more trouble .....just a thought for someone that might be poor like me.. The ac delco is 50 60 bucks cheaper

02-06-2007, 04:57 PM	#9 (permalink)
MMA_Alex Registered User Join Date: Apr 2006 Location: Downeast, ME/Rochester, NY Posts: 1,421	ac delco shudder... when the truck is running the battery regulates the voltage, and smoothes it out. It's not as much of a problem because of the voltage regulator built into the alt, but I still wouldn't risk it because if you fry the comp its not exactly $20 down at autozone to replace it.

02-06-2007, 08:45 PM	#10 (permalink)
^VooDoo^ Contributing Member Join Date: Mar 2006 Location: Alhambra CA. Posts: 395	No, The battery is only there to start the engine and keep memory for the ECU, clock and radio, Once the engine is started there should be no need for the battery at all, The internal regulator should do the work or its bad. Pulling the neg terminal off while its running is one of the easyest ways to check for bad alt, But also turn on other accesories like AC or highbeams. Remember aftermarket equipment like lights, winch and amps are not in the origanal design concept, So the size of the alternator output is was only intended for the factory equipment. This has not changes since the first alternator/regulators were installed.