FD Alternator Into S4 Wiring Problems and then some.
01-11-12, 05:35 PM
#26
Driving RX7's since 1979
iTrader: (43)
Join Date: Aug 2001
Location: So Cal where the OC/LA/SB counties meet
Posts: 6,096
Likes: 0
Received 8 Likes
on
8 Posts
ok guys i know this is a old bump but i need help and and need more info before i start cutting wires. yes i searched thats how i got this.
so from the FD alt:
the B terminal goes directly to the battery via a fuse or not?
L goes to L
S terminal gets spliceed to EGI fuse
On S4 chassis:
oem B terminal gets capped off/ unused
oem R terminal gets capped off/ unused
now for the B terminal from the FD alt do u need to splice it to the MAIN FUSE or can i just add my own fuse going to the battery?
let me know if this sounds right or if im way off. asap guys i wants this done!!! lol
so from the FD alt:
the B terminal goes directly to the battery via a fuse or not?
L goes to L
S terminal gets spliceed to EGI fuse
On S4 chassis:
oem B terminal gets capped off/ unused
oem R terminal gets capped off/ unused
now for the B terminal from the FD alt do u need to splice it to the MAIN FUSE or can i just add my own fuse going to the battery?
let me know if this sounds right or if im way off. asap guys i wants this done!!! lol
01-18-12, 01:18 AM
#29
ok i connected the b+ from the alt to the battery and put the s wire to the battery and its still not charging. battery is reading only 12.03v at idle!!! alternator isnt doing anything, when i turn on head lights it drops down to 11.90v, i think i may have a bad alternator or im still doing something wrong. plz help
01-18-12, 09:08 AM
#30
W/key to on do your idiot lights come on as they should? If so then you know you didn't cross up the L and S terminals. Is the contact point between the B terminal and its cable a clean one? Have you tried measuring the voltage from the B terminal while idling to see how it compares to the voltmeter reading?
01-18-12, 10:15 AM
#32
Disconnect the L terminal wire, which on the stock harness should be the White/Black wire, (and not the Black/White wire so don't confuse the two) and w/key to on ground the White/Black wire and see if the idiot lights turn on. If by chance you have the Black/White wire connected to the L terminal then do not ground this wire but just make sure the wire you are grounding is the White/Black wire and not Black/White.
01-18-12, 11:52 AM
#33
GuiltySoul, I want you to IGNORE everything else in this thread except for what I'm about to show and tell you. When I did mine in 2008, there seemed to be much confusion about how to wire it correctly, and that seems to still be here. As such, I found that the diagram in the FAQ was wrong and made my own which proved to work correctly.
There is NO cutting needed to use a FD Alternator in your S4 car if you have a FD Alternator pigtail. You will need to upgrade the Output Cable (you called it B+ Cable) to 4awg. Visit your local welding supply store such as DeLille and ask for 3ft of 4awg Welding Cable and two cable lugs. This will be more than enough. I went there yesterday and it was $1.58 per foot, compared to $4 for battery cable at Oreilly Auto Parts.
Follow this diagram to the letter and it will work correctly. Rev it to ~2000 rpm to wake it up if your alternator is a tad sleepy like mine was
While it is not necessary to the alternator's operation, removing the old output cable is a wise choice to prevent shorting out against the UIM. De-loom it back to the fuse box and you'll see that it's T-spliced into the fuse panel to battery cable. Snip it off with diagonals and cover it with electrical tape and maybe some split loom too.
The end result will be that you'll have an 8awg cable from the fuse panel, a 4awg cable from the starter (stock is black w/yellow stripe) and a 4awg cable from the alternator, all converging at the battery's positive terminal. Using marine-type battery terminals with wing nuts to attach the lugs is probably a good idea too.
If you're feeling ambitious, now would be a good time to replace all of the battery cables. Chances are your battery cables are not in great shape and have several breaks in the insulation like mine did. Aaron Cake has a great write-up on doing this correctly, using welding cable. Only thing I can add to it is to be sure to put a band of red electrical tape around the positive starter cable on both ends so you don't mix them up.
There is NO cutting needed to use a FD Alternator in your S4 car if you have a FD Alternator pigtail. You will need to upgrade the Output Cable (you called it B+ Cable) to 4awg. Visit your local welding supply store such as DeLille and ask for 3ft of 4awg Welding Cable and two cable lugs. This will be more than enough. I went there yesterday and it was $1.58 per foot, compared to $4 for battery cable at Oreilly Auto Parts.
Follow this diagram to the letter and it will work correctly. Rev it to ~2000 rpm to wake it up if your alternator is a tad sleepy like mine was
While it is not necessary to the alternator's operation, removing the old output cable is a wise choice to prevent shorting out against the UIM. De-loom it back to the fuse box and you'll see that it's T-spliced into the fuse panel to battery cable. Snip it off with diagonals and cover it with electrical tape and maybe some split loom too.
The end result will be that you'll have an 8awg cable from the fuse panel, a 4awg cable from the starter (stock is black w/yellow stripe) and a 4awg cable from the alternator, all converging at the battery's positive terminal. Using marine-type battery terminals with wing nuts to attach the lugs is probably a good idea too.
If you're feeling ambitious, now would be a good time to replace all of the battery cables. Chances are your battery cables are not in great shape and have several breaks in the insulation like mine did. Aaron Cake has a great write-up on doing this correctly, using welding cable. Only thing I can add to it is to be sure to put a band of red electrical tape around the positive starter cable on both ends so you don't mix them up.
01-18-12, 03:16 PM
#36
The White/Black wire is supposed to receive a ground from the alternator w/key to on and it is this ground that causes the idiot lights to come on. Now you say your idiot lights don't come on. Why do you suppose that is? Perhaps the W/B is not receiving the necessary ground w/key to on. Now how would you go about figuring this out, especially since your alternator is currently not working properly?
01-18-12, 04:41 PM
#39
Sorry if I ruffled your feathers Satch, I'm just a big believer in doing things right from the very start with the simplest means, ala Aaron Cake. I made that diagram after testing it on my own car to make sure it works.
Overbuild the car, underwork it and it'll last forever.
Yes it will make a large difference, because your car won't catch fire with 4awg. Always size the wire for the MAXIMUM current it will see. I like to go a step further and add 15-20% on top of that as a safety margin, so 4awg is what I used. As an added bonus, I didn't have to replace it when I upgraded to a 130A taurus alternator. Even that monster would burn out before the cable is pushed too far.
8awg just can't handle 100 amps going through it, but you can re-use the old output cable for E-fan wiring should you go that route later. Coincidentally, starters for manual FCs/FDs draw about 100 amps according to Ohm's Law (1200 watts/12 volts=100 Amps) and use 4awg cable.
Overbuild the car, underwork it and it'll last forever.
i have a 8 awg wire to the battery now. will a 4 awg really make a diffence? i do have 4 gauge wire in the garage i guess i could give it another try
8awg just can't handle 100 amps going through it, but you can re-use the old output cable for E-fan wiring should you go that route later. Coincidentally, starters for manual FCs/FDs draw about 100 amps according to Ohm's Law (1200 watts/12 volts=100 Amps) and use 4awg cable.
01-18-12, 04:49 PM
#40
He said his idiot lights don't work and it all starts at the alternator so how was my advice at odds with "I'm just a big believer in doing things right from the very start with the simplest means." His idiot lights not working is not related to the gauge of a wire used as there is something else at play here, thus I'm suggesting he start at the beginning.
01-18-12, 06:38 PM
#41
Driving RX7's since 1979
iTrader: (43)
Join Date: Aug 2001
Location: So Cal where the OC/LA/SB counties meet
Posts: 6,096
Likes: 0
Received 8 Likes
on
8 Posts
Right,
I agree with Akagis in respect to over engineering when doing modifications. So 4awg is indeed a good choice for the "B" wire sending current to the battery et. al.
However, it does seem he reversed the W/b and B/w wires as satch is suggesting.
- The W/b (L) wire sends a ground (will leak between .5 - 4.5 volts but should be less than 1 volt for bright idiot lights) signal to the idiot lights.
- The B/w (S) wire is the sensor wire that needs to see the battery positive constantly for either an S5 or S6(FD) alternator. On an S4, this B/w wire is factory wired to only see the battery positive when the key is on. Thus why you need to cut it and run it directly through a fuse to the battery positive. If you don't make this modification, the alterntor will drain the battery when the car is at rest via the B wire.
Bottom line - If the B/w & W/b wires were reversed, his regulator would be fried (which sounds like it is). If fried, then even if he were to now reverse the wires to a correct connection, he still would get no idiot lights BECAUSE the regulator is fried. More over, if the regulator was fried, I would expect he would be getting 15+ volts rather than the lower voltage indicated. Thus his whole alternator is probably now fried.
To the OP
Make sure the connections are correct and THEN replace the alternator.
I agree with Akagis in respect to over engineering when doing modifications. So 4awg is indeed a good choice for the "B" wire sending current to the battery et. al.
However, it does seem he reversed the W/b and B/w wires as satch is suggesting.
- The W/b (L) wire sends a ground (will leak between .5 - 4.5 volts but should be less than 1 volt for bright idiot lights) signal to the idiot lights.
- The B/w (S) wire is the sensor wire that needs to see the battery positive constantly for either an S5 or S6(FD) alternator. On an S4, this B/w wire is factory wired to only see the battery positive when the key is on. Thus why you need to cut it and run it directly through a fuse to the battery positive. If you don't make this modification, the alterntor will drain the battery when the car is at rest via the B wire.
Bottom line - If the B/w & W/b wires were reversed, his regulator would be fried (which sounds like it is). If fried, then even if he were to now reverse the wires to a correct connection, he still would get no idiot lights BECAUSE the regulator is fried. More over, if the regulator was fried, I would expect he would be getting 15+ volts rather than the lower voltage indicated. Thus his whole alternator is probably now fried.
To the OP
Make sure the connections are correct and THEN replace the alternator.
01-19-12, 10:38 AM
#46
ok i just check the wiring and it doesnt seem i messed up in wiring.
the top wire from the alt (s) [green/w] is going to the battery
the bottom wire is going to the (L) wire which is the white/b wire and the black/w wire is doing nothing
now HOZZMANRX7, u said...
"- The B/w (S) wire is the sensor wire that needs to see the battery positive constantly for either an S5 or S6(FD) alternator. On an S4, this B/w wire is factory wired to only see the battery positive when the key is on. Thus why you need to cut it and run it directly through a fuse to the battery positive. If you don't make this modification, the alterntor will drain the battery when the car is at rest via the B wire."
whats the best way to wire the B/W to and will it fix the problem??
the top wire from the alt (s) [green/w] is going to the battery
the bottom wire is going to the (L) wire which is the white/b wire and the black/w wire is doing nothing
now HOZZMANRX7, u said...
"- The B/w (S) wire is the sensor wire that needs to see the battery positive constantly for either an S5 or S6(FD) alternator. On an S4, this B/w wire is factory wired to only see the battery positive when the key is on. Thus why you need to cut it and run it directly through a fuse to the battery positive. If you don't make this modification, the alterntor will drain the battery when the car is at rest via the B wire."
whats the best way to wire the B/W to and will it fix the problem??
01-19-12, 12:14 PM
#47
Driving RX7's since 1979
iTrader: (43)
Join Date: Aug 2001
Location: So Cal where the OC/LA/SB counties meet
Posts: 6,096
Likes: 0
Received 8 Likes
on
8 Posts
Refer to Akagis's diagram but with minor difference as I chose to isolate the connection to the battery akin to stock design.
There should be an empty slot in the main fuse box by the battery. Run the B/w wire to one side of that empty fuse slot, then simply push in a 30 amp fuse into the empty slot.
Problem is, you probably have killed the grounding circuit in the regulator what with the reversed wiring you had. So you may have to replace the alternator (or at least the regulator) as well to get the idiot lights working again.
There should be an empty slot in the main fuse box by the battery. Run the B/w wire to one side of that empty fuse slot, then simply push in a 30 amp fuse into the empty slot.
Problem is, you probably have killed the grounding circuit in the regulator what with the reversed wiring you had. So you may have to replace the alternator (or at least the regulator) as well to get the idiot lights working again.
Thread
Thread Starter
Forum
Replies
Last Post
The Shaolin
2nd Generation Specific (1986-1992)
9
09-14-15 07:50 PM
blkops
3rd Generation Specific (1993-2002)
7
08-12-15 01:30 PM
