heres the story

my friend and i did a full S5 swap in to my 10AE which included the ECU we custom fabricated the harness and everything worked for a summer but sooner or later i started to have a power drain like the car would just go dead, for example i would be driving and when i step on the brakes the radio would turn off and the interior lights would start dimming, if i gave the car more gas the car wouldnt respond it would be very very sluggish and hesitate, the steering wheel would be stiff and difficult to steer, if i turned the car off it wouldnt start again... a temperary cure for this problem was to charge the battery when needed and the car would run for a day or 2, then charge the battery again and repeat...

i then swapped in a newer battery parked it for winter and only took it out 3 weeks ago, and the problem was no where to be found, until last night... i heard a loud "pop" sound and the problems listed above started to come back... i checked the battery terminals and they're fine, i checked the main fuses and the fuses in the cabin and they look fine ... im really lost and cant afford to have this car in this condition...

i would like to mention that before all these problems that when doing an oil change someone put the jack to close to my starter and when i started the car my 80A fuse blew and i just replaced it... this is just an assumtion though i really dont know why the 80A fuse blew...

 

could be a grounding problem? check all of your grounds.

 

yea grounding problems must be the cause, start checking around the alternator and battery with a DMM, it would be nice if you had a volt gague to go off of.

 

In my car everything runs perfectly, but I do notice at night when i have the lights on and the car is idling at 750, when i step on the break pedal the headlights and interior lights will dim just a little be but it is noticeable. Is this normal or should I check and reground?

 

Your problem is a classic description of a mis-wired alternator that is starting to fail.

did you use a S4 alt or S5 alt and how is it wired???

 

yeah sounds like a ground problem to me...

 

im using a S4 alt, i have no idea how it was wired, do you have any more insite?

all the grounds are all good no grounding problems, but will recheck

 

What Icemark is driving at is there are differences in the feedback loop between an S4 alternator and an S5/S6 alternator. If you are using an S5 harness with an S4 alternator, it may be wired incorrectly.

 

yep, the S4 alt needs a switched ignition source, while the S5 and S6 wire to a constant source.

In addition the colors of the input reference and the run reference are exactly opposite between the S4 and S5... which would lead the to alt draining that battery when parked and failing to charge correctly when running.

 

OOoooOOO so notorious! FC + electricals = fail. I'd say get the S6 alt.

 

so will i need to replace the alt with a S5 or can i still use a S4?..... and for wireing is there anyone that can refer me to a wireing diagram or "walk though"

 

87RX7Girl posted up a relatively handy pictorial representation of the different alternators:

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/r-terminal-531961/