overcharging

jfries89 · 01-08-2009, 06:20 PM

just replaced my alternator and now it charges at 17 volts at idle. does anybody kno where the voltage regulator is? i cant seem to find it

Papo J · 01-08-2009, 06:57 PM

If it's an NA it is bolted to the back of the alternator, if it's an SC it's mounted to the firewall in the trunk on the right side and about 1.5' from the ECU. Did you measure it with a meter? Don't trust the gauge too much.

jfries89 · 01-08-2009, 06:59 PM

its an n/a. yea i checked it with a multimeter. but i just replaced the alternator today. any ideas as to why its doin this? i dont kno if this is related but i have the three warning lights i guess. the cooling fan light the brake light and the charge light are all on

Papo J · 01-08-2009, 08:22 PM

All of those lights indicate a faulty alternator or charging system. Did you get a cheap replacement alternator, like from autozone? If you did take it back, get an OEM alternator if you can.

jfries89 · 01-08-2009, 09:54 PM

hmmmmm...... yea i did. do you mean from toyota? are you sure it couldnt be a short in a wire or something?

Papo J · 01-09-2009, 08:03 AM

A short wouldn't give you 17V at the battery and something would've burnt by now.

tjmr2 · 01-09-2009, 11:55 PM

Check the resistance of the white wire - (the heavy wire you secure with a nut to the back of the alternator) to the + side of the battery. Disconnect it from the alternator first, it should read about 0 ohms. If you have a reading over 5 to 10 ohms you may have corrosion in the wire. It is just crimped together between the alternator and the battery, and over time corrosion can get down the wire and eat it causing the symptoms you describe.

It's a pain to find as you have to peel the insulation and tape off the wiring harness.
(been there done that)

Good luck

jfries89 · 01-17-2009, 12:55 PM

ok. this alternator ******** is starting to piss me off now. now this second new one that i got that was working is now not working. any suggestions? just take it back again?

Timon · 01-17-2009, 01:28 PM

If you got it from autozone or checkers, any typical parts store. Yes take it back. I actually had the same 3 warning lights you had a mere 3 days ago. I actually got a rebuilt alternator from a junk yard, OEM N/A MR2 alternator, and it works wonderfully. Car starts on a dime now. 15 minutes to remove the old one, an hour to install that damn pivot bolt by myself on the new one. Either return your current one, if they complain about it have them test it while it's on the car.

Your only other option is to test the cable going from the battery to the alternator, as Tjmr2 said, but I don't see a corroded wire causing it to overcharge - normally a corroded wire wouldn't allow enough of a charge due to the bad connection.

This is probably due to bad voltage regulators in the alternator. If they'd be willing to give your old one back, you could have it rebuilt entirely (that was going to be $140 for me, which is why I didn't do it), or you can just replace the voltage regulator yourself. Unbolt the 4 8mm nuts from the housing of the alternator that the connector plugs into, then using a phillips screw driver remove the 4 or 5 screws holding the voltage regulator in. If you have a manual it gives a full diagram of the alternator.

jfries89 · 01-18-2009, 01:36 AM

well this time its just not charging. and the wire going from the alternator to the battery only has 2 ohms of resistance

Timon · 01-18-2009, 08:06 AM

When it's connecting I'm assuming? If so, then yes you need a new alternator, or at the least a new voltage regulator. Same problem I had. The alternator refuses to charge the battery.

I feel sorry for you going onto your 3rd alternator. I hope you have someone else to line up that pivot bolt

.

jfries89 · 01-18-2009, 10:05 AM

oh well. its not actually that hard for me. i do it from under the car and it basically just slips in

Timon · 01-18-2009, 03:48 PM

Mine had to be pounded in with a 2x4 and a hammer from the top, and then slowly tapped in from the bottom - of course I couldn't get it right the first time. I had to go from top to bottom, top to bottom, etc. until I lined it up perfectly for the pivot bolt to slide in. After that it was cake.

jfries89 · 01-19-2009, 12:01 AM

that's weird mine just slides right in

Timon · 01-19-2009, 01:24 AM

There's like a welded, metal washer towards the driver's side on the pivot bracket that allows the alternator to hold itself up with no bolts in it. Chances are yours doesn't have this, and probably doesn't hold itself up without the pivot bolt in either. I don't know why some cars have this and others don't.

yikes · 01-19-2009, 10:37 AM

Pull apart, check for signs of arcing, clean, snap together the large white connector that is rearward and below the battery. Cut off and replace the "O" connector at the alternator (white wire). Do this even if the next alt. works. Peace of mind.
If you have room the slip a washer in the bracket for the pivot bolt, do so and check that there is no slop between the bolt and the alt. If the alt. can turn a little, the belt will not run true and will rip itself apart.

jfries89 · 01-19-2009, 11:31 PM

well i took off the alternator and took it back today. but when i took the wire that gets bolted on to the alt the coating cracked. so tomorrow i am going to replace it. just one question tho, would putting a larger wire (smaller gauge number, id say that the stock one is about 10 or 12 so maybe put in 8?) affect it negatively?

Timon · 01-20-2009, 12:20 AM

It shouldn't have any negative impact, especially only going to the next size - just don't go smaller.

01-08-2009, 06:20 PM	#1 (permalink)
jfries89 first time owner Join Date: May 2008 Location: tallahassee Posts: 51 Thanks: 1 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	overcharging just replaced my alternator and now it charges at 17 volts at idle. does anybody kno where the voltage regulator is? i cant seem to find it

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01-08-2009, 06:57 PM	#2 (permalink)
Papo J 6SPD GTE Join Date: Sep 2006 Posts: 591 Thanks: 2 Thanked 50 Times in 49 Posts iTrader Rating: (0/0% )	If it's an NA it is bolted to the back of the alternator, if it's an SC it's mounted to the firewall in the trunk on the right side and about 1.5' from the ECU. Did you measure it with a meter? Don't trust the gauge too much.

01-08-2009, 06:59 PM	#3 (permalink)
jfries89 first time owner Join Date: May 2008 Location: tallahassee Posts: 51 Thanks: 1 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	its an n/a. yea i checked it with a multimeter. but i just replaced the alternator today. any ideas as to why its doin this? i dont kno if this is related but i have the three warning lights i guess. the cooling fan light the brake light and the charge light are all on

01-08-2009, 08:22 PM	#4 (permalink)
Papo J 6SPD GTE Join Date: Sep 2006 Posts: 591 Thanks: 2 Thanked 50 Times in 49 Posts iTrader Rating: (0/0% )	All of those lights indicate a faulty alternator or charging system. Did you get a cheap replacement alternator, like from autozone? If you did take it back, get an OEM alternator if you can.

01-08-2009, 09:54 PM	#5 (permalink)
jfries89 first time owner Join Date: May 2008 Location: tallahassee Posts: 51 Thanks: 1 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	hmmmmm...... yea i did. do you mean from toyota? are you sure it couldnt be a short in a wire or something?

01-09-2009, 08:03 AM	#6 (permalink)
Papo J 6SPD GTE Join Date: Sep 2006 Posts: 591 Thanks: 2 Thanked 50 Times in 49 Posts iTrader Rating: (0/0% )	A short wouldn't give you 17V at the battery and something would've burnt by now.

01-09-2009, 11:55 PM	#7 (permalink)
tjmr2 Cage Fighter Join Date: Jan 2008 Location: Colorado Posts: 410 Thanks: 0 Thanked 62 Times in 59 Posts My Google Map iTrader Rating: (0/0% )	Check the resistance of the white wire - (the heavy wire you secure with a nut to the back of the alternator) to the + side of the battery. Disconnect it from the alternator first, it should read about 0 ohms. If you have a reading over 5 to 10 ohms you may have corrosion in the wire. It is just crimped together between the alternator and the battery, and over time corrosion can get down the wire and eat it causing the symptoms you describe. It's a pain to find as you have to peel the insulation and tape off the wiring harness. (been there done that) Good luck

01-17-2009, 12:55 PM	#8 (permalink)
jfries89 first time owner Join Date: May 2008 Location: tallahassee Posts: 51 Thanks: 1 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	ok. this alternator ******** is starting to piss me off now. now this second new one that i got that was working is now not working. any suggestions? just take it back again?

01-17-2009, 01:28 PM	#9 (permalink)
Timon MR2 MKI AW11 Join Date: Feb 2008 Location: Utah Posts: 669 Thanks: 13 Thanked 42 Times in 37 Posts My Google Map iTrader Rating: (1/100% )	If you got it from autozone or checkers, any typical parts store. Yes take it back. I actually had the same 3 warning lights you had a mere 3 days ago. I actually got a rebuilt alternator from a junk yard, OEM N/A MR2 alternator, and it works wonderfully. Car starts on a dime now. 15 minutes to remove the old one, an hour to install that damn pivot bolt by myself on the new one. Either return your current one, if they complain about it have them test it while it's on the car. Your only other option is to test the cable going from the battery to the alternator, as Tjmr2 said, but I don't see a corroded wire causing it to overcharge - normally a corroded wire wouldn't allow enough of a charge due to the bad connection. This is probably due to bad voltage regulators in the alternator. If they'd be willing to give your old one back, you could have it rebuilt entirely (that was going to be $140 for me, which is why I didn't do it), or you can just replace the voltage regulator yourself. Unbolt the 4 8mm nuts from the housing of the alternator that the connector plugs into, then using a phillips screw driver remove the 4 or 5 screws holding the voltage regulator in. If you have a manual it gives a full diagram of the alternator.

01-18-2009, 01:36 AM	#10 (permalink)
jfries89 first time owner Join Date: May 2008 Location: tallahassee Posts: 51 Thanks: 1 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	well this time its just not charging. and the wire going from the alternator to the battery only has 2 ohms of resistance

01-18-2009, 08:06 AM	#11 (permalink)
Timon MR2 MKI AW11 Join Date: Feb 2008 Location: Utah Posts: 669 Thanks: 13 Thanked 42 Times in 37 Posts My Google Map iTrader Rating: (1/100% )	When it's connecting I'm assuming? If so, then yes you need a new alternator, or at the least a new voltage regulator. Same problem I had. The alternator refuses to charge the battery. I feel sorry for you going onto your 3rd alternator. I hope you have someone else to line up that pivot bolt .

01-18-2009, 10:05 AM	#12 (permalink)
jfries89 first time owner Join Date: May 2008 Location: tallahassee Posts: 51 Thanks: 1 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	oh well. its not actually that hard for me. i do it from under the car and it basically just slips in

01-18-2009, 03:48 PM	#13 (permalink)
Timon MR2 MKI AW11 Join Date: Feb 2008 Location: Utah Posts: 669 Thanks: 13 Thanked 42 Times in 37 Posts My Google Map iTrader Rating: (1/100% )	Mine had to be pounded in with a 2x4 and a hammer from the top, and then slowly tapped in from the bottom - of course I couldn't get it right the first time. I had to go from top to bottom, top to bottom, etc. until I lined it up perfectly for the pivot bolt to slide in. After that it was cake.

01-19-2009, 12:01 AM	#14 (permalink)
jfries89 first time owner Join Date: May 2008 Location: tallahassee Posts: 51 Thanks: 1 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	that's weird mine just slides right in

01-19-2009, 01:24 AM	#15 (permalink)
Timon MR2 MKI AW11 Join Date: Feb 2008 Location: Utah Posts: 669 Thanks: 13 Thanked 42 Times in 37 Posts My Google Map iTrader Rating: (1/100% )	There's like a welded, metal washer towards the driver's side on the pivot bracket that allows the alternator to hold itself up with no bolts in it. Chances are yours doesn't have this, and probably doesn't hold itself up without the pivot bolt in either. I don't know why some cars have this and others don't.

01-19-2009, 10:37 AM	#16 (permalink)
yikes Cage Fighter Join Date: Feb 2005 Location: Gnaw Bone, Indiana Posts: 230 Thanks: 2 Thanked 12 Times in 4 Posts iTrader Rating: (0/0% )	Pull apart, check for signs of arcing, clean, snap together the large white connector that is rearward and below the battery. Cut off and replace the "O" connector at the alternator (white wire). Do this even if the next alt. works. Peace of mind. If you have room the slip a washer in the bracket for the pivot bolt, do so and check that there is no slop between the bolt and the alt. If the alt. can turn a little, the belt will not run true and will rip itself apart.

01-19-2009, 11:31 PM	#17 (permalink)
jfries89 first time owner Join Date: May 2008 Location: tallahassee Posts: 51 Thanks: 1 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	well i took off the alternator and took it back today. but when i took the wire that gets bolted on to the alt the coating cracked. so tomorrow i am going to replace it. just one question tho, would putting a larger wire (smaller gauge number, id say that the stock one is about 10 or 12 so maybe put in 8?) affect it negatively?

01-20-2009, 12:20 AM	#18 (permalink)
Timon MR2 MKI AW11 Join Date: Feb 2008 Location: Utah Posts: 669 Thanks: 13 Thanked 42 Times in 37 Posts My Google Map iTrader Rating: (1/100% )	It shouldn't have any negative impact, especially only going to the next size - just don't go smaller.