Wires To Alternator Help

cre · 03-06-2010, 09:43 PM

I should add that if you use the battery's negative terminal for your ground and measure a proper voltage at the alternator's output lug but the voltage at the battery is very low you needn't bother with the other wiring on the alternator, just follow the wiring from the alternator's lug to the battery.

You can also to a voltage drop test (negative test lead to the alt's lug and positive test lead to the battery's positive terminal), the reading should be very low, more than half a volt and you need to track the drop using the same methodology until you find the cause; You can do this test across just the fusible link to see if the fusible link is the culprit, but you have to pull the section it's mounted in out of the fuse box housing so I usually test the drop across the whole thing first.

MA70-3.0GT · 03-08-2010, 05:44 PM

Basically then, if the alternator's throwing out any charge then it should be evident across a chassis earth & the lug when the engine's running? I'm getting 11.69 & dropping with higher revs both across earth/alt. lug & across battery terminals. Everything seems to check out continuity wise with my wiring but still no charge. I'm beginning to think reg/rec failure...

Oh, another thing I noticed was after a ten minute drive the other day the casing of the alt was quite hot (if I'd really pressed my hand on hard it would've hurt). To me that says the thing's working but the charge isn't getting past the reg/rec...

cre · 03-09-2010, 01:35 AM

I would just pull the alternator out and take to a parts store to have it tested... Here they all do it for free and it's easy to do. That's VERY low and below the ECU's minimum from what I've been told.

btwilson86 · 03-09-2010, 07:40 AM

I 2nd that, get it tested. Some stores can test the regulator/diodes while it's on the car, so you literally just drive there.

SuperSpartan · 07-01-2010, 02:26 AM

I sometimes get that issue and am curious to how can i identify and replace the fusible link, cause all the signs point to that.

cre · 10-03-2010, 07:47 PM

ALT 100A FL in the engine bay fuse box.

Some aftermarket power wires also have a FL in the middle of them; just a 1" to 2" sections of a different diameter is what you can look for.

cre · 10-03-2010, 10:19 PM

Um... you know it comes out from the bottom, right? And you can use a sealed one as specified for later years in place of the wire if your car had the wire.

03-06-2010, 09:43 PM	#1
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	I should add that if you use the battery's negative terminal for your ground and measure a proper voltage at the alternator's output lug but the voltage at the battery is very low you needn't bother with the other wiring on the alternator, just follow the wiring from the alternator's lug to the battery. You can also to a voltage drop test (negative test lead to the alt's lug and positive test lead to the battery's positive terminal), the reading should be very low, more than half a volt and you need to track the drop using the same methodology until you find the cause; You can do this test across just the fusible link to see if the fusible link is the culprit, but you have to pull the section it's mounted in out of the fuse box housing so I usually test the drop across the whole thing first. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

03-08-2010, 05:44 PM	#2
MA70-3.0GT 12psi boost Join Date: Oct 2009 Location: Crewe, England Posts: 356	Basically then, if the alternator's throwing out any charge then it should be evident across a chassis earth & the lug when the engine's running? I'm getting 11.69 & dropping with higher revs both across earth/alt. lug & across battery terminals. Everything seems to check out continuity wise with my wiring but still no charge. I'm beginning to think reg/rec failure... Oh, another thing I noticed was after a ten minute drive the other day the casing of the alt was quite hot (if I'd really pressed my hand on hard it would've hurt). To me that says the thing's working but the charge isn't getting past the reg/rec... __________________ '89 MA70 Supra GT aero 3.0turbo JDM, Rebuilt motor, K&N intake, 3" stainless turbo-back. New turbo and braided line kit... '89 Honda NC27 400, NC23 cams, open pipe, PC36a shock & possibly Showa USD forks... '83 Yamaha 29R XJ750E-II, number 69 off the line, only runner in the country? Original except Koni shocks '95 Honda PC26 CB500R, Winter hack, hateful, trying to sell it I'm not paranoid, they really ARE after me!!! Last edited by MA70-3.0GT; 03-08-2010 at 05:46 PM. Reason: I can't spell!

03-09-2010, 01:35 AM	#3
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	I would just pull the alternator out and take to a parts store to have it tested... Here they all do it for free and it's easy to do. That's VERY low and below the ECU's minimum from what I've been told. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

03-09-2010, 07:40 AM	#4
btwilson86 Super Moderator Join Date: May 2007 Location: Billings, Montana Posts: 1,034	I 2nd that, get it tested. Some stores can test the regulator/diodes while it's on the car, so you literally just drive there. __________________ 1989 7MGTE R154 Targa Top White Package w/Blue Interior Driftmotion 57trim CT26, Upgraded Intercooler, 2.25" Hard Pipes, 3" Turbo Back Exhaust with Test Pipe, HKS VPC w/GM 3 bar MAP sensor, APEXi S-AFC, Walbro 255lph fuel pump, ProSport EVO Series Boost / Fuel Pressure / AFR gauges, Lotek a Pillar Gauge Pod, HKS Type 0 Turbo Timer, Eibach Lowering Springs, Tokico Illumina II TEMS struts, custom powder coated Motegi Racing TrakLite wheels

07-01-2010, 02:26 AM	#5
SuperSpartan 3" Exhaust Join Date: Mar 2008 Location: Tucson Arizona Posts: 97	I sometimes get that issue and am curious to how can i identify and replace the fusible link, cause all the signs point to that. __________________ 1990 Toyota Supra Turbo!! www.cardomain.com/ride/3067504

10-03-2010, 07:47 PM	#6
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	ALT 100A FL in the engine bay fuse box. Some aftermarket power wires also have a FL in the middle of them; just a 1" to 2" sections of a different diameter is what you can look for. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

10-03-2010, 10:19 PM	#7
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Um... you know it comes out from the bottom, right? And you can use a sealed one as specified for later years in place of the wire if your car had the wire. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

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