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iTrader: (2)

Hello ,

Quick run down of problem ,


Na front harness ( S4 ), E6x ecu . S5 Alternator ( turbo ) .

Breaking in motor for the past week, and noticed voltage problem.

Initial start up and I get 12.6 volts ( what ever the battery holds ) then after I touch the gas ( say past 1500 rpm) voltage goes to 15.1 volts.

I then swapped for another S5 alternator exactly same thing, then I swapped a 3rd S5 alternator exactly same thing.

Then I thought well then , The alternator is problably misswired (battery does NOT drain ) .

After cheacking it seemed fine ( wired according to psyclo last wiring diagram post ) . wich was

white black to terminal L , black white capped off and not used ( this was used for terminal R on S4 alternator ) .
then IT had fused 12v from fuse box going to terminal b looped and going to terminal S .

So I said well maybe the looping or my grounds are not that great. So went to the local shops and bought stereo 4 gauge and 12 gauge.

I completely redid my ''MAIN" power lines in 4 gauge. and the grounds.

and this time I separated the terminal S and B, terminal B gets fused 12v and terminal S straight from battery .

So I just finished and started car same problem , at start says 12.6 volts II started moving and no more 15.0-15.1 volts but 15.5 .

So right now I really dont know what to do .

Any help would be great.

and volt reading is comming from the haltech .

spot_skater

If it doesn't spike to above like 15.5-16v I wouldn't worry too much. 14.6v is what it should be at, and too high of voltage could definitely damage some electronics.

Read up a little bit about the haltech and see how much voltage is safe to run through it. It could be as high as 18v, so if it is your safe. Either way I would definitely check all the wiring you did.

The reason the voltage bumps up when you hit the gas is because the alternator is spinning faster, so it's creating more voltage after a certain RPM. At idle with all electrical loads on it's not uncommon for voltage readings to drop to 13v, but cruising at 2k rpm's it'll probably be around 14.6.

Look at it this way, your charging system is really good, lol.

Icemark

15.5 is about a volt too high.

I'd be checking with an voltmeter (instead of a ECU) to see if that is real

twistedriver

The stock voltage gauge gets stuck sometimes so make sure your reading is correct. My stock gauge moves a little everytime i hit the gauge custer.

RETed

Verify with a DMM?


-Ted

J-Rat

iTrader: (2)

....

Syonyk

What are you checking voltage with?

Use a good DMM on the battery posts & report the numbers - I spent half the winter chasing voltage problems on my motorcycle, only to find out that the voltmeter I have (in an aftermarket unit with a clock & thermometer) is inaccurate when really hot, or really cold - it reads about a volt low when it's below 50 out.

-=Russ=-

classicauto

iTrader: (3)

.................................................. .............................................
Read much? haha


Anyways, like has been said I would want to verify the voltage at the battery and from the battery's ground to the the + post on the alternator.

If indeed you are getting 15 or more volts after countless alternator swaps I would first try another battery. I have seen this on other vehicles in the shop before, even though the battery is good (i.e. lots of CC amps and seems to be workign well) it may be "calling" for too much from the altenator and causing the alternator to exceed its regulated voltage. Not really sure what exacty "breaks" in a battery to cause this but I have seen it in a number of vehicles with overcharging issues.

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iTrader: (2)

Thanks for all the replies, just got around to check right now. I checked everything within garage ( mmm gas ).

Okey here are results,

Initial ( not running )

Haltech --12.5
Battery --12.4 ( measured with DMM )

Start up

haltech 12.6
Battery posts 12.6 ( + - )

touch throttle once to 1500 rpm

Haltech 14.5
battery 14.4

touch throttle again to 1500 rpm

haltech 15.2
battery 15.2
alernator post to battery negative 15.1

And I assume if I take car around the block it will jump to 15.5 V .

The battery only has 2000 km, ( but I guess it might have gotten damaged )

I will see if I can borrow a battery to check .

Also I believe this Voltage problem is giving me ignition break up at higher rpms ( no boost yet ) .

So Im really lost on this one, I dont know if I should swap in a S4 and let it be.

2 of the 3 alternators were checked at the local auto parts shop and they passed ( didnt give any detail, just said passed ).

Any other thoughts ?

----------------------------------

Im using a pre 86 front harness , is there a chance that the white( with black ) and black ( with white ) are interchanged ?


Thanks again for the help

classicauto

iTrader: (3)

hmm I guess there's a possibility that the wirs are different, and with a (for all intents and purposes) new battery that probably isn't causing the issue.

Maybe PM Hailers and see if he knows of any differences between the wiring on pre vs. post 86 harness'?

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iTrader: (2)

update:

Just installed a perfectly working new optima red top exactly same symtoms. So its not the battery.

And regarding the wires , I doubt they would change it but its the only other thing i could think off.

So I went and got alternator tested again , and it passes.

But I remember reading that the S5 and S6 alternators have 4 diodes instead of 1 ( like the S4 ) .

so maybe the machine that checks the alternator only checks for one good diode.

So we procedede to hook up one of those testers that checks charging system, cranking amps, battery.

And battery turned out 100 % healthy ( non optima one ) . cranking amps on battery are 700 actually had 720 .

Now read same as above,

start car, 12.5 volts steady , touch gas goes to 13.8 then again gas and goes to 15.

Then it checked diodes/ripples and said non existant.

And then when we revved the engine, the charging volts went done ( dont know exactly why ) .

So I think it was just luck that all 3 were sort of damamged. ( only thing that buggles my mind is that if a diode is dead then the battery would LOOSE charge wich it does not.

So im down to , all 3 alternators had a blown diode, or soemthing is miswired that is not reading/getting a right signal.

any more help .

Boostmaniac

just underdrive it and call it a day maybe?

FC3S.USD

iTrader: (2)

well , What I did is swapped in an old S4 alternator. And well Its running at 14.3 -14.4 volts. ( wich is super high for a S4, I have never seen one run that high )

So i think its something that I dont understand haha.

So I think that issue is done. Oh and still have igntion issues so they were not related.
Time to fix that problem.

So if anyone has any data with regards to why the tested good S5 alternators are running like I would love to hear.

( I think all in all, Alternators just run voltage happy in the car )

tri_tam

i have the same problem too
it's kinda like the alternator doesn't charge or see ignition source when just start up the car.
untill step on the gas to rev over 2k rpm then it all good... but my didn't went over 14.7v
and that's a fd alternator from a guy on this forum use to sell it.
o yeah i have to un plug the alternator wire at the back of the warning light too...
if not all the warning light just lite up all the time... like ignition on without engine run...
i don't really know ... i must have short something


*edit*
oh i see...
maybe i din't get much of high volt like you, because i have RB crank undrive and the alternator kit from that guy come with an under drive too.. i think.

Ravingecu21

yo this is sick i have the same problem right now so i took it to the shop how can u fix this?

Icemark

It is supposed to run at 14.4 volts. If it is not then there is an issue.

How did you wire the alt??? it sure sounds like if you swap a S4 one in, and it works fine, that you did not wire the S5 or S6 alt correctly (they do not plug and play... wires need to be changed between the series).

Icemark

If it is a FD/S6 alt, then it should never "see" ignition. FD and S5 alts wire entirly different than S3 and S4 alts.

Well that there confirms that you did not wire that alt up correctly at all. You have the Referance and run (S and L ) leads backwards.

No, you just installed the alt incorrectly.

tri_tam

i did install these in an S4 beforce, and it was find.
now it's in a S5 body.. which plug in and play IIRC.
i didn't mess up any wiring on the drive in the S5 car. hum.... maybe i did after all

Icemark

If the idoit lights are always coming on, on a S5 then the alt is not wired correctly, but rather the ref and run leads (S and L) are backwards.

See the idiot lights should come on if there is ground on the run lead... but the ref lead is looking for voltage (On the FD, battery voltage), and the regulator will appear to have ground on it.

The run lead will have ground when the alt is not moving and voltage when the alt is moving. It feeds 12 volts to the idiot lights (or CPU on S4 models) breaking the circuit to ground.

Its a common mistake that FC owners have been doing forever. People seem to think that the colors stay the same for all years and don't test function. Rather the wires change colors and pin locations for each series. For the longest time people putting in FD alternators thought you had to use a relay or diode when installing it to prevent battery drain and problems like you describe, when it was just they wired the alt incorrectly.

FD/S6 alt wiring:


Here is the S5 Alt wiring:


and the S4 alt:


See the Black/White is the referance lead on the S4 models, while it is the White/Blue on S5 models... the big difference is that the Referance lead goes to the battery on the S5 and S6 models, but people often just hook it up to the S4 Black/White and wonder why the alt's regulator is always powered.

Or they swap it with the white/black, and on the S4, that looses power through the CPU relay, which the regulator then trys and power up to make up for the loss through the relay, spiking the alt up past the 14.4 volts that it is supposed to run at. Remember if the alt is indeed wired correctly, it should never ever ever ever exceed 14.7 volts output. If it does, (and the alt is wired correctly) then the alt should be replaced.