FD alternator in S4
04-09-14, 12:02 PM
#1
FD alternator in S4
My S4 alternator is slowly dying, and I can get an FD alternator from someone locally.
I did some searching on here, but found a lot of broken links. From what I can tell from the descriptions I found is that the FD alternator will mount up to the S4's alternator brackets, but you need to use the FD pigtail wired into the existing loom. I found the wiring diagram on the FAQ:
https://www.rx7club.com/2nd-generati...7/#post5131072
I was wondering if the R terminal wire from the S4 goes to the S terminal on the FD pigtail. Is the L terminal from the S4 the same as the S5? Are there any other wiring changes?
I did some searching on here, but found a lot of broken links. From what I can tell from the descriptions I found is that the FD alternator will mount up to the S4's alternator brackets, but you need to use the FD pigtail wired into the existing loom. I found the wiring diagram on the FAQ:
https://www.rx7club.com/2nd-generati...7/#post5131072
I was wondering if the R terminal wire from the S4 goes to the S terminal on the FD pigtail. Is the L terminal from the S4 the same as the S5? Are there any other wiring changes?
04-09-14, 01:28 PM
#2
04-09-14, 02:04 PM
#4
As a FD alternator was my first mod, I'd like to point out a couple things
The wiring guide is technically correct, but fails to factor in that the positive terminal is overloaded with connections on most cars. On a bone-stock FC, it has two cables: one to starter, and one to fuse box, which has the Alternator cable spliced into it via a staple.
If you are using stock or common OEM-type terminals from the parts store, you'll run out of space on the terminal to attach cables to. Plus, you need to upgrade the alternator cable to 4awg, putting you into the overloaded category even further.
This is the reason why I say that wiring cleanup is part of an alternator upgrade. This includes new Marine battery terminals of which you can attach all 3 of the cables to. The proper method is to divorce the alternator and fuse box's 8awg cables from each other. From the fuse box's main fuse, start inching back to the battery, pulling tape off as you go. Keep going untill you find the splice/staple. Repeat the process, starting at the alternator. Once you get them un-taped, pull them out and re-tape the Engine Harness. Cut near the splice, and toss the old alternator cable aside. Crimp a new ring terminal onto the Fuse Box cable and attach it to the Marine Battery Terminal. Now run some fresh 4awg from the alternator to the battery terminal, about 30" will do and wire as shown here:
Although unrelated to the alternator, I have found it to be good practice to tackle the Starter Cables at this time too. It's the same process: untape the Front Harness, extract the cables, re-tape the harness and put in fresh, new 4awg cables. 48" is good for positive terminal to starter, while two 24" ones are right for the negative terminal to Main Ground and MG to Starter Ground. This replaces the funky and corrosion-prone 3-terminal original ground cable. Just follow the guide here and it'll be nice and happy: Proper RX-7 Grounding Procedures
One thing I have found to be useful is to thread the new Main Ground bolt in from the wheel well. Before doing so, make sure the threads in the body are clean and de-gunked as mentioned in the article. Putting the bolt in from the wheel side gives you a stud to hook the cables onto when securing them. Much easier to do this than try and hold two cables and a bolt together at angles that can be challenging with A/C in the car.
Extracting the cables from the Front and Engine Harnesses is a filthy job, but well worth the effort.
The wiring guide is technically correct, but fails to factor in that the positive terminal is overloaded with connections on most cars. On a bone-stock FC, it has two cables: one to starter, and one to fuse box, which has the Alternator cable spliced into it via a staple.
If you are using stock or common OEM-type terminals from the parts store, you'll run out of space on the terminal to attach cables to. Plus, you need to upgrade the alternator cable to 4awg, putting you into the overloaded category even further.
This is the reason why I say that wiring cleanup is part of an alternator upgrade. This includes new Marine battery terminals of which you can attach all 3 of the cables to. The proper method is to divorce the alternator and fuse box's 8awg cables from each other. From the fuse box's main fuse, start inching back to the battery, pulling tape off as you go. Keep going untill you find the splice/staple. Repeat the process, starting at the alternator. Once you get them un-taped, pull them out and re-tape the Engine Harness. Cut near the splice, and toss the old alternator cable aside. Crimp a new ring terminal onto the Fuse Box cable and attach it to the Marine Battery Terminal. Now run some fresh 4awg from the alternator to the battery terminal, about 30" will do and wire as shown here:
Although unrelated to the alternator, I have found it to be good practice to tackle the Starter Cables at this time too. It's the same process: untape the Front Harness, extract the cables, re-tape the harness and put in fresh, new 4awg cables. 48" is good for positive terminal to starter, while two 24" ones are right for the negative terminal to Main Ground and MG to Starter Ground. This replaces the funky and corrosion-prone 3-terminal original ground cable. Just follow the guide here and it'll be nice and happy: Proper RX-7 Grounding Procedures
One thing I have found to be useful is to thread the new Main Ground bolt in from the wheel well. Before doing so, make sure the threads in the body are clean and de-gunked as mentioned in the article. Putting the bolt in from the wheel side gives you a stud to hook the cables onto when securing them. Much easier to do this than try and hold two cables and a bolt together at angles that can be challenging with A/C in the car.
Extracting the cables from the Front and Engine Harnesses is a filthy job, but well worth the effort.
04-09-14, 03:56 PM
#5
As a FD alternator was my first mod, I'd like to point out a couple things
The wiring guide is technically correct, but fails to factor in that the positive terminal is overloaded with connections on most cars. On a bone-stock FC, it has two cables: one to starter, and one to fuse box, which has the Alternator cable spliced into it via a staple.
If you are using stock or common OEM-type terminals from the parts store, you'll run out of space on the terminal to attach cables to. Plus, you need to upgrade the alternator cable to 4awg, putting you into the overloaded category even further.
This is the reason why I say that wiring cleanup is part of an alternator upgrade. This includes new Marine battery terminals of which you can attach all 3 of the cables to. The proper method is to divorce the alternator and fuse box's 8awg cables from each other. From the fuse box's main fuse, start inching back to the battery, pulling tape off as you go. Keep going untill you find the splice/staple. Repeat the process, starting at the alternator. Once you get them un-taped, pull them out and re-tape the Engine Harness. Cut near the splice, and toss the old alternator cable aside. Crimp a new ring terminal onto the Fuse Box cable and attach it to the Marine Battery Terminal. Now run some fresh 4awg from the alternator to the battery terminal, about 30" will do and wire as shown here:
Although unrelated to the alternator, I have found it to be good practice to tackle the Starter Cables at this time too. It's the same process: untape the Front Harness, extract the cables, re-tape the harness and put in fresh, new 4awg cables. 48" is good for positive terminal to starter, while two 24" ones are right for the negative terminal to Main Ground and MG to Starter Ground. This replaces the funky and corrosion-prone 3-terminal original ground cable. Just follow the guide here and it'll be nice and happy: Proper RX-7 Grounding Procedures
One thing I have found to be useful is to thread the new Main Ground bolt in from the wheel well. Before doing so, make sure the threads in the body are clean and de-gunked as mentioned in the article. Putting the bolt in from the wheel side gives you a stud to hook the cables onto when securing them. Much easier to do this than try and hold two cables and a bolt together at angles that can be challenging with A/C in the car.
Extracting the cables from the Front and Engine Harnesses is a filthy job, but well worth the effort.
The wiring guide is technically correct, but fails to factor in that the positive terminal is overloaded with connections on most cars. On a bone-stock FC, it has two cables: one to starter, and one to fuse box, which has the Alternator cable spliced into it via a staple.
If you are using stock or common OEM-type terminals from the parts store, you'll run out of space on the terminal to attach cables to. Plus, you need to upgrade the alternator cable to 4awg, putting you into the overloaded category even further.
This is the reason why I say that wiring cleanup is part of an alternator upgrade. This includes new Marine battery terminals of which you can attach all 3 of the cables to. The proper method is to divorce the alternator and fuse box's 8awg cables from each other. From the fuse box's main fuse, start inching back to the battery, pulling tape off as you go. Keep going untill you find the splice/staple. Repeat the process, starting at the alternator. Once you get them un-taped, pull them out and re-tape the Engine Harness. Cut near the splice, and toss the old alternator cable aside. Crimp a new ring terminal onto the Fuse Box cable and attach it to the Marine Battery Terminal. Now run some fresh 4awg from the alternator to the battery terminal, about 30" will do and wire as shown here:
Although unrelated to the alternator, I have found it to be good practice to tackle the Starter Cables at this time too. It's the same process: untape the Front Harness, extract the cables, re-tape the harness and put in fresh, new 4awg cables. 48" is good for positive terminal to starter, while two 24" ones are right for the negative terminal to Main Ground and MG to Starter Ground. This replaces the funky and corrosion-prone 3-terminal original ground cable. Just follow the guide here and it'll be nice and happy: Proper RX-7 Grounding Procedures
One thing I have found to be useful is to thread the new Main Ground bolt in from the wheel well. Before doing so, make sure the threads in the body are clean and de-gunked as mentioned in the article. Putting the bolt in from the wheel side gives you a stud to hook the cables onto when securing them. Much easier to do this than try and hold two cables and a bolt together at angles that can be challenging with A/C in the car.
Extracting the cables from the Front and Engine Harnesses is a filthy job, but well worth the effort.
One question I did have was can I just splice in a FD pigtail to the existing wiring loom for now? The S4 alternator is close to dying, and this is my daily for the summer. I have every intention to change the wiring to see if various electrical things start working again in the car.
04-11-14, 04:17 PM
#6
Yes, the FD pigtail can be spliced in to get you going. However, I have found it simpler and easier to just crimp two 1/4" quick Disconnect tab connectors onto the pigtail's wires and insert them into the stock S4 connector per my diagram.
While it's not up to my personal standards for wiring cleanliness, using Quick Disconnect tabs works, does it for under $1 and it can be reverted to stock in 5 seconds. Kind of hard to argue with that
If you're feeling up to making it nice and tidy, a matching connector can be found on a bunch of different cars. S4s use them in many locations, such as the rear speakers, stereo and taillights. But don't forget the rule of any project: Make it work, then make it pretty.
While it's not up to my personal standards for wiring cleanliness, using Quick Disconnect tabs works, does it for under $1 and it can be reverted to stock in 5 seconds. Kind of hard to argue with that
If you're feeling up to making it nice and tidy, a matching connector can be found on a bunch of different cars. S4s use them in many locations, such as the rear speakers, stereo and taillights. But don't forget the rule of any project: Make it work, then make it pretty.
04-12-14, 07:29 PM
#7
Yes, the FD pigtail can be spliced in to get you going. However, I have found it simpler and easier to just crimp two 1/4" quick Disconnect tab connectors onto the pigtail's wires and insert them into the stock S4 connector per my diagram.
While it's not up to my personal standards for wiring cleanliness, using Quick Disconnect tabs works, does it for under $1 and it can be reverted to stock in 5 seconds. Kind of hard to argue with that
If you're feeling up to making it nice and tidy, a matching connector can be found on a bunch of different cars. S4s use them in many locations, such as the rear speakers, stereo and taillights. But don't forget the rule of any project: Make it work, then make it pretty.
While it's not up to my personal standards for wiring cleanliness, using Quick Disconnect tabs works, does it for under $1 and it can be reverted to stock in 5 seconds. Kind of hard to argue with that
If you're feeling up to making it nice and tidy, a matching connector can be found on a bunch of different cars. S4s use them in many locations, such as the rear speakers, stereo and taillights. But don't forget the rule of any project: Make it work, then make it pretty.
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04-25-14, 12:07 PM
#8
NA-BOOSTIN
Is there somewhere I can find a fd alt pigtail by chance . Trying to finish my engine harness and trackin down the last few pigtails I need . Any other make / model that uses that plug by chance ?
04-25-14, 12:59 PM
#9
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