Known Good Alternator Not Charging Battery
Known Good Alternator Not Charging Battery
okay so i have put my motor in after a rear iron swap and have this problem now. it did not have this problem originally. i am using a ford 130 amp alt, rebuilt, and even tested today at autozone and passed. the battery is brand spankin new. car starts up, idles, but when you try to give it more than half throttle it sounds like its on antilag. at first i thought it had something to do with the rtek that i put in, swapped it out with the stocker, same thing. checked all the wiring for the alt, is good and connected properly (idiot light, and vol ref and wired properly. next i checked the b terminal wire, was continuos from the fuse block to alt. so i thought okay maybe a break in the wire somewhere. so i hooked up a 4 ga wire from the b terminal to the fuse block and still no avail. i have checked the fuse block, all fuses are good. anymore suggestions? i am really stumped, i havent changed anything wiring related only swapped the motor out and in. i have even checked the starter wiring just making sure it wasnt done wrong. i know surley im missing something, but i cant think what so any ideas would be fantastic.
Rotary Freak
Joined: Jul 2008
Posts: 1,660
Likes: 2
From: FORT WORTH TEXAS
You can read the volage on the RTEK 2.0 IF that's what you have. What does it read when the engine is idling and when the revs are a bit over 1000 rpm?
Not a RTEK2.0? Then what does the alt read using multimeter at idle and just over 1000 rpm.
No meter? Harbor Freight has them for less than ten bucks.
I'm not sure why you say it's the alternator unless the batt goes flat after a few minutes and you can't start/crank the engine.
Not a RTEK2.0? Then what does the alt read using multimeter at idle and just over 1000 rpm.
No meter? Harbor Freight has them for less than ten bucks.
I'm not sure why you say it's the alternator unless the batt goes flat after a few minutes and you can't start/crank the engine.
talking head
Joined: Apr 2008
Posts: 2,775
Likes: 15
From: Perth, WA, OZ
if you fit the alt ( s5 ) with parallel pins in its small wires you have to be sure the pin closest to the B+ is wired to the battery ( and not just the B + )
if you fit the alt with the T plug,, top of the T is black with white and must be wired to the ignition switch or coil
if you fit the alt with the T plug,, top of the T is black with white and must be wired to the ignition switch or coil
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I read through that thread i guess i should explain my set up more. Car is a s4 with a ford alt. It has a regulator which has a three wire plug. Yellow w/ wht i have wired to the + side of the battery to my knowledge this is the vol ref wire, which tells the alt were u want to see 13.8v. The middle wire loops back to a seperate pin on the alt and green with red i have hooked up to the idiot light wht/blk from the stock harness
Joined: Apr 2005
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From: And the horse he rode in on...
Before u go on about how bad it is and the long continuos story that has been covered and read by many on other alt threads, i know its not good for it. My multimeter is not set up to run that much amps in series through the dmm if it is even producing any, and simply testing the voltage at the alt wont work because the battery is new and im seeing suffecient voltage at the alt with the car on.
Joined: Apr 2005
Posts: 3,785
Likes: 30
From: And the horse he rode in on...
Before u go on about how bad it is and the long continuos story that has been covered and read by many on other alt threads, i know its not good for it. My multimeter is not set up to run that much amps in series through the dmm if it is even producing any, and simply testing the voltage at the alt wont work because the battery is new and im seeing suffecient voltage at the alt with the car on.
You know you can pull a spark plug wire off while the car is running too?
talking head
Joined: Apr 2008
Posts: 2,775
Likes: 15
From: Perth, WA, OZ
from a mustang forum -
http://www.allfordmustangs.com/forum...ustang-gt.html
by sounds of this you wire the switching wire to the I pin via the dash warning light and there is no " warning light output " per say
i would suggest that the rx7 warning light works on opposite polarity and thus is not suitable for use as the field wire on this alt unless you get a relay and get tricky
else it should be wired to ignition switch +
hopefully you can glean something from this post and it all helps
http://inlinethumb60.webshots.com/46...500x500Q85.jpg
http://www.allfordmustangs.com/forum...ustang-gt.html
If the alternator is really not the problem, the only thing other than a simple loose connection at the alternator, or something in the harness close by is the "I" signal that "tells" the alternator that the car is on and that it needs to get to work.
On some cars this is simply tied to the ignition switch and goes positive when the ignition switch is in position 2, or "run".
On other cars, this positive voltage is supplied THROUGH the idiot light in the instrument cluster. An intermittent connection at the bulb, or a flaky bulb can keep the alternator from operating.
This circuit is traditionally the cause of the most frustration with a non-producing, or intermittent alternator.
I am attaching a diagram of the connectors involved and a wiring diagram of a typical 3G setup.
http://inlinethumb60.webshots.com/46...500x500Q85.jpg
The 3G has a "stud" on the back that is the "fused" charging line to the battery. This is fused in case the ALTERNATOR shorts out and provides a dead-short to ground for your battery. The charge line will glow red-hot and start a fire if your diodes short out and this fuse doesn't exist. This "battery" connection is usually one of the studs on the starter solenoid/relay.
Next, there is a 3-pin connector:
The "A" signal goes to a battery connection. Sometimes it is looped over to the charging "stud" on the back of the alternator, but usually it follows the charge lead to the stud on the starter relay.
The "S" signal simply loops over and connects to the single-pin connector labeled "S".
The "I" signal is the one mentioned above that receives a positive 12 volts to tell the Alternator that the car is on and that it needs to get to work.
Those are ALL of the connections needed for a 3G alternator to work!
Below is a wiring diagram that shows this pictorally.
http://inlinethumb53.webshots.com/41...600x600Q85.jpg
On some cars this is simply tied to the ignition switch and goes positive when the ignition switch is in position 2, or "run".
On other cars, this positive voltage is supplied THROUGH the idiot light in the instrument cluster. An intermittent connection at the bulb, or a flaky bulb can keep the alternator from operating.
This circuit is traditionally the cause of the most frustration with a non-producing, or intermittent alternator.
I am attaching a diagram of the connectors involved and a wiring diagram of a typical 3G setup.
http://inlinethumb60.webshots.com/46...500x500Q85.jpg
The 3G has a "stud" on the back that is the "fused" charging line to the battery. This is fused in case the ALTERNATOR shorts out and provides a dead-short to ground for your battery. The charge line will glow red-hot and start a fire if your diodes short out and this fuse doesn't exist. This "battery" connection is usually one of the studs on the starter solenoid/relay.
Next, there is a 3-pin connector:
The "A" signal goes to a battery connection. Sometimes it is looped over to the charging "stud" on the back of the alternator, but usually it follows the charge lead to the stud on the starter relay.
The "S" signal simply loops over and connects to the single-pin connector labeled "S".
The "I" signal is the one mentioned above that receives a positive 12 volts to tell the Alternator that the car is on and that it needs to get to work.
Those are ALL of the connections needed for a 3G alternator to work!
Below is a wiring diagram that shows this pictorally.
http://inlinethumb53.webshots.com/41...600x600Q85.jpg
i would suggest that the rx7 warning light works on opposite polarity and thus is not suitable for use as the field wire on this alt unless you get a relay and get tricky
else it should be wired to ignition switch +
hopefully you can glean something from this post and it all helps
http://inlinethumb60.webshots.com/46...500x500Q85.jpg
talking head
Joined: Apr 2008
Posts: 2,775
Likes: 15
From: Perth, WA, OZ
as amends to the above posts ,, some later ford 3 wire alternators are switched from the ECU and require PWM signals along the middle and outer wires ( 125 Hz )
if you leave the 3 pin plugged disconnected these will default charge for 14.0 V as seen at the B+ output
if you leave the 3 pin plugged disconnected these will default charge for 14.0 V as seen at the B+ output
Thank you bumpstart ill try to switch the i wire (grn/red) to the 12v switched wire that is blk/wht for the stock alt instead of the wht/blk that i have it wired to.
Rotary Freak
Joined: Jul 2008
Posts: 1,660
Likes: 2
From: FORT WORTH TEXAS
Hello. On a series four car the White/Black is switched voltage from the METER fuse.
The White/Black is NOT coming from a idiot light. See the free online wiring diagrams for the series four alterantor.
Just turn the key to ON and with the white/black not connected to the alt check for volage. Should see batt voltage IF the METER fuse is good and or IF the CPU elect connector is on the CPU.
Not talking serires five idiot lights in any way or fashion.
The White/Black is NOT coming from a idiot light. See the free online wiring diagrams for the series four alterantor.
Just turn the key to ON and with the white/black not connected to the alt check for volage. Should see batt voltage IF the METER fuse is good and or IF the CPU elect connector is on the CPU.
Not talking serires five idiot lights in any way or fashion.
Some alternators require the Alt Windings to have a supply of power in order to start up the alternator. This power is supplied on the 'excitation wire.' However some alternators, when revved, have the ability to self exite and start working.
So, if you take the advice of a friend and not the advice of the forum, you end up hooking up the excitation wire of your FD alt swap to a switched +12V instead of a constant +12V source. When you do this your alternator doesn't turn on right away and you have to rev the car, to about 4000rpm, to get the alternator to turn on. If its too cold out my car will studder and not hit the 4000 rpm till it has some time to run. I do plan on fixing this, it just hasn't been a priority yet.
So, if you take the advice of a friend and not the advice of the forum, you end up hooking up the excitation wire of your FD alt swap to a switched +12V instead of a constant +12V source. When you do this your alternator doesn't turn on right away and you have to rev the car, to about 4000rpm, to get the alternator to turn on. If its too cold out my car will studder and not hit the 4000 rpm till it has some time to run. I do plan on fixing this, it just hasn't been a priority yet.
Well i switched to blk/wht to the i wire and the alt now works, i do see in the diagrams that wht/blk goes through the alt warning light relay in the cpu after the 7.5 amp meter fuse, blk/wht also come from the same kickpanel fuse block and is 15 amp fused then a straigh run to the alt. What else runs off the meter fuse? Maybe that fuse is blown? I didnt find one in the kickpanel blown
Rotary Freak
Joined: Jul 2008
Posts: 1,660
Likes: 2
From: FORT WORTH TEXAS
NZCONVERTIBLE did a swell job in that thread telling what is what on the fuse box. I must have missed that thread when it was first posted yrs ago.
IF your gauges work, then the METER fuse is good.
The W/B actually is on one side of the coil of the Alt Relay (NOT the contacts of the relay, but the coil of that relay). Again ithe power from the METER fuse passes thru one side of the relays COIL to the other side of that coil and then heads for the alternator where it usually finds a ground inside the alt and that pulls in the alt relay whose contacts then make and put a Ground on the Warning Light assy's light bulbs (all the bulbs) which makes them all come on 'cause they already have power going to the other side of each bulb (just looking for a ground so they can turn on and light up).
IF you turn the key ON and then look at the white/black connector you should see approx batt voltage. Maybe the 50 ohm resistance of the alt coil plus the diode inbetween causes a lack of enough amperage to make the alt work? Got me. I just know approx 12vdc is there if the key is ON.
IF your gauges work, then the METER fuse is good.
The W/B actually is on one side of the coil of the Alt Relay (NOT the contacts of the relay, but the coil of that relay). Again ithe power from the METER fuse passes thru one side of the relays COIL to the other side of that coil and then heads for the alternator where it usually finds a ground inside the alt and that pulls in the alt relay whose contacts then make and put a Ground on the Warning Light assy's light bulbs (all the bulbs) which makes them all come on 'cause they already have power going to the other side of each bulb (just looking for a ground so they can turn on and light up).
IF you turn the key ON and then look at the white/black connector you should see approx batt voltage. Maybe the 50 ohm resistance of the alt coil plus the diode inbetween causes a lack of enough amperage to make the alt work? Got me. I just know approx 12vdc is there if the key is ON.
Since Jross427 mentioned a 130 Amp Ford Alternator, I'm gonna take a wild guess and say it's from an early 90s 3.8L Taurus.
Here is a diagram for the S4 cars, tested on my own 1987 GXL with a FD Alt, then immediately swapped to a 3.8L Taurus Alt. If you wire it like this, I guarantee it will work.
Here is a diagram for the S4 cars, tested on my own 1987 GXL with a FD Alt, then immediately swapped to a 3.8L Taurus Alt. If you wire it like this, I guarantee it will work.
Joined: Apr 2005
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From: And the horse he rode in on...
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