Before i start i just want to say that i did search this topic and i read quite a few threads and i'm aware this topic has been beat to death.....I just want to get some input concerning my specific situation. My voltage changes as i drive. Upon a cold start (during the accelerated warm up period) the voltage is at its highest...(the gauge in the dash reads about 14 or so).....As the engine warms up, the voltage drops...once the engine reaches operating temp, the voltage will settle around 12v at idle......As i press on the gas pedal (increase the RPMS), the voltage goes up as well, but not by much.....it drops as the engine goes back to idle speed...the interior dash lights get dimmer while idling esp with my foot on the brake pedal...the rear defroster also causes the idle to drop significantly if i have it on (from 12v down to 11.5 or so)....on a side note, i checked the voltage at the battery with a DMM this morning with the engine off and no key in the ignition...it read 12.4v...which is pretty close to normal from what i've read....i started the car up and the voltage read around 15v at the battery......Ive been thru a few batteries and a few alternators...Im currently using a S5 alt in my S4 N/A.....Does anyone have any idea what the problem can be?

 

Hmmm... check your battery connections maybe. I have the same problem, I might just go with a fd alternator.

 

i have a battery thats a few months old that seems ok (starts good and seems to have normal voltage with engine off)....i also have new terminal connections...I was reading that some have run wire from the + battery terminal to the alt and run another wire from the - battery terminal to the chassis to help improve voltage issues...i may try that

 

hi,

your issue is the conversion..

series 4 alt is a resistive load alt

series 5 is a load sensative alt

both are connected in different ways, a load sensative alt needs all its connection to be correct for it to work properly....

by not connecting the load sensative alt proprly the voltage output is "floating".

connect it right and the problem will be gone..

keep running it like this and the regulator will toast itself and dead alternator you will have.


this is the thread you should have read - https://www.rx7club.com/showthread.p...ght=alternator

i even explain your exact issue -

cheers

 

U say n your original thread that the S5 alt swap is plug and play. What exactly do u mean by that? Am i supposed to disregard the diagram since im usng a S5 alt? what did i do wrong? the swap seemed pretty str8 forward...the location and connectors between the 2 series alts is the main difference. A friend and i cut the 2 chassis wires and the 2 alt connector wires and spliced them together. i printed up a diagram for us to follow.

 

Look at his drawing and look at the SERIES FIVE ALTERNATOR IN THE ATTACHED JPG.

LOOK at the SHAPE of the connector on the SERIES FIVE ALTERNATOR. Determine which blade is for the S wire and which is for the L wire.

Don't put the wires on the wrong blade of the alternators jack.

Your series four had two wires. One is BLACK/WHITE. Don't use that wire. Do what he says in his dwg. Tie it back out of the way.

Connect the series four WHITE/BLACK to the L blade of the alternators jack. Its the one on the right side of the jack.

Run a new wire to the S terminal from either the battery or the engine bay fuse box. It should have a FUSE b/t it and the battery. See his drawing.

Pay attention to the SHAPE of the JACK on the alternator. It determines where the L and S wires go.

When thru, turn the key to ON, engine OFF. With a meter, backprobe the L wire. It should read approx 1-3vdc with all wires/plugs connected to the alternator. IF it does not, find out why not.

 

thanx hailers! u made t alot easier to understand!

 

I rewired the s5 alt for my car and the voltage seems to still be low. I do have a crane cams ignition system...i wonder if that has something to do with it. theres a wire coming from it that goes to the positive on the battery

 

Shouldn't.

 

Yeah Hailers i did everything u explained in your post and the voltage hasnt changed. The B Terminal should remain unchanged during the wiring process correct?

 

So, to be absolutely totally clear in regards to putting an S5/S6 alternator in an S4:

S4 "R" Terminal
- The Black/White wire that would normally run to the "R" terminal on an S4 Alternator doesn't get connected to anything in the S5/S6 alternator retrofit process. You simply insulate the end with tape or shrinking tubing and tuck it away.

- Out of curiosity, what functionality is being eliminated by doing this? I'm guessing it's what provides the "Resistive load" (thus "R") for the S4 alternator that isn't needed for an S5/S6 alternator.

S4 & S5 "L" Terminal
-The White/Black wire runs to the "L" terminal in all cases.

S5/S6 "S" Terminal
- I assume "S" stands for Sensitive.

- Bottom line, adding the new wire to the constant 12V is what provides the needed S5/S6 functionality an S4 isn't designed for stock.

- Rather than run a new wire all the way from the alternator to the battery, why wouldn't you simply just run the "S" wire to the "B" terminal on the alternator since in both cases they run directly to the battery? It would seem that all that would be needed is a 30 amp inline fuse (as the FSM calls for to the S terminal otherwise) between the S and B terminals.

 

correct, insulate and tuck away.

the ignition source isnt needed for the new alt so not much point leaving it float out in the open un insulated.

correct

yep adding the new wire connect the alternator how it should be in its factory install..


UNDER ALL CIRCOMSTANCES DO NOT DO THIS!!!!

have a look at the original wiring diagrams for the series 5/6. were does it get its supply - from the battery

there is a reason for this. an alternator doesnt put out true DC volts.. its the battery that keeps it a constant DC voltage.

i tried this actual install when i first started installing them into early mazdas(connecting S to B+) and we had issues with the voltage spiking to 16 to 17volts on some cars (its called limp mode).

basically cause the input for the S terminal was getting a "dirty signal" the regulator would go haywire..

so definetly do not do this as it might look like - same, same but different. it is definetly far from it..



and dont forget to upgrade your alternator B+ wire.

just do this (the diagram) fold back your original B+ cable as well and insulate it and a happy alt you will have when you connect it like below



cheers

 

ok well i got the EXACT same problem but I am still running the S4 alternator...

 

"UNDER ALL CIRCOMSTANCES DO NOT DO THIS!!!!

have a look at the original wiring diagrams for the series 5/6. were does it get its supply - from the battery

there is a reason for this. an alternator doesnt put out true DC volts.. its the battery that keeps it a constant DC voltage.

i tried this actual install when i first started installing them into early mazdas(connecting S to B+) and we had issues with the voltage spiking to 16 to 17volts on some cars (its called limp mode).

basically cause the input for the S terminal was getting a "dirty signal" the regulator would go haywire..

so definetly do not do this as it might look like - same, same but different. it is definetly far from it."

Never in a million years would I have guessed this would be an issue all things considered. But your actual experience can't be denied. THANKS!!

 

I'm going back to a S4 alt.....its like Mazda went out of its way to make s5 cars as different from s4's as humanly possible.....

 

your regulator is dead, it needs servicing.

voltage fluctuations arent healthy for the ecu/engine either..

 

only to glad to help man..

 

more often than not the reg ***** itself from the alt being overloaded.
due to extra electrical accessories added and Mazda series 4 design is very tight on the amount of capacity left on the alt after the stock configuration.

so by not upgrading the alt you just keep going in a loop of smashing regulators and dead alternators... which will eventually cost you batteries as well.


im sorry but with all due respect that comment is so wrong its not funny.
you ask any car manufacturer. if it aint broken dont fix it..
if faults come through on the model upgrade whats not working properly.

the electrical system was changed from series 4 to series 5 cause of the exact issues being seen with your series 4 (70 amp alternator).

so they UPGRADED the system to 80 amp alt and adjusted the wiring to suit the extra capacity and wiring requirements in the series 5!!

but if your going to upgrade might as well go series 6 as its the same wiring as the series 5 and same pulley mod. but with an extra 20 amps to play with over the series 5 = definetly a better option..

 

I looked at the other post u chimed in on concerning the fd alt in a s4. I remember looking at the diagram...u said something about the s4 to s5 being plug and play. what difference is there between wiring up a s5 alt and a s6 alt to a s4 car? I already have a dual pulley installed on my alt b/c the ac, airpump and ps were removed

 

Small undersized dual pulley?

I know nothing about the size of Mazdatrix/RacingBeat pulleys. I ASSume their all undersized. Don't KNOW that to be a fact.

Getting the right wire on the right terminal of the alternator jack matters. If you get it wrong for a significant amount of time, then the regulator can become worthless.

 

i looked at mazdatrix website ....the dul pulley they sell looks like the one i have. is there a different dual pulley that works better?

 

The RB and Mazdatrix pulleys are all advertised as being underdrive, thus larger diameter. Stock sized or smaller than stock are difficult to find. Thus an opportunity for someone out there to fill this niche demand.

 

I have my s5 alt set up exact as your diagram desribes.....complete with the inline fuse....i rewired it last week...... i had been running the car with the alt hooked up incorrectly for probably about 3 months....so i guess the regulator could be shot now....

 

See if when you remove the white/black wire if you have batt voltage on it with the key to ON.

Then put it back on the alternator and backprobe the white/black with the key ON. It should be 1-3vdc.

Then if that stuff works out, take the thing to a auto store that tests the alternators for free and see how things turn out.

 

On review of soooo many threads found via the beloved search button on FD alternators into S4's, this thread paints the clearest how-too picture on this subject.

Good job guys.