yes I know this was talked about once but for some reason I can't get the search to work
it just sits there forever after I try

but it seems voltage at idle after I start the car is only like 12v
if I turn my headlights on and rear defroster it drops to around 9v or so


not good

as far as the install goes I couldn't find the directions silverrotor had so I looked on the web

the stock harness had a white wire with black stripe and black wire with white stripe

with the directions I foun it was black wire with white stripe goes to the top plug on the alt and I did that but still just sits there and idles at low voltage

now I will be honest and say I didn't try it out much being it was late at night and I was at a friends house and didn't want to rev the car up to see if th voltage goes up and wake everyone else around the house up


but I know on my s4 alt the voltage goes to about 13.5v with nothing on right after start up

this one just sits there like I am running on batt

any ideas?

 

Give this a shot, rev the car to about 2500-3k and the alternator should give higher voltage readings. If not, check the voltage across the battery and across the alternator. If one is lower that the other then you have a problem in the wiring (not spliced in with a good connection).

Also if the voltage does pick up after you rev it up alittle, you just had the same problem I had. I think since they are new, they need to be broken in. I have not had any problems with mine since, it only got better the more I drove mine.

Hope that helps!

 

Disconnect the alternator and run the car. If the car only runs for a very SHORT time, its most likely a bad battery. If it continues to run it could be the alt.
Like the other guy (lol I forgot his name) said, if you rev the engine and they get brighter ir is probably an alternator problem. THat is the basic solution.
If you want to try more before you buy a new alternator, I would recommend using a multimeter to test current and voltages across all the wires from the alt to the battery to the lights. It is possible you have a short somewhere and when you hit the lights it's pulling hella excess current.
(sounds like it was written by a pro, huh :-P)

 

with reving the car to 2500-3000 rpms giving me a nice reading is it ONLY when it is reved up that high

or once it hits that point it will stay reading high?

as far as the batt being bad
this started RIGHT AFTER the switch from a s4 alt to the FD alt

the s4 alt read fine all the time so don't think the batt is dead


and thought all the alts that silverrotor gave out where tested to be good



as far as a short in the system
the only wires touched where the wire connecting to the post
and the 2 wires that go to the plug
though I admit there might be a problem there and will check the voltage though them but they should be good as far as I can tell since they have a nice good splice on them right now

but any other ideas?

 

NO NO NO NO BAD BAD BAD BAD.... Never disconnect the battery on a running alt with a integrated regulator (as found in our cars)...

That advice is micky mouse advice from the 60's and should never ever be done. There are voltage meters in non-turbos, and a multi-meter at radio shack is less than $40.

At best disconnecting a battery while running won't harm anything, at worst it will waste the alt completely (as well as every electrical device in the car including the ECU). Remember the battery acts as a giant capacitor while the engine is running. Disconnecting it while running and the voltage can spike and burn up everything.

If the voltage is less than 12.6 volts the car is running on the battery and the alt is not putting out enough voltage to even keep the battery charged.

 

Heres my at idle with the s5 alt

 

pretty low

 

What might cause this? Even at rev, I never see it go above the next mark above 12v...?

 

A FD alt should be above the 14 volt mark even at idle. Infact a newer S4 alt would even be above the 14 volt mark at idle.

If it is not, then the alt is bad, wired wrong, or the grounds are very bad on the engine.

 

as far as the wiring

the wire that went to the post is on the post on the fd alt

the black wire with white stripe (from the stock wires) goes to the upper wire on the fd plug the one with the white wire and black stripe goes to the lower plug wire on the plug

sound right?

everything else worked fine with the s4 alt
and I changed nothing else
just d/c the s4 alt hooked the fd alt up

so don't see how it would a short,bad grounds, bad batt or anything like that since they worked just fine about 20 min before with the s4 alt. and I didn't touch any other wires or anything

 

I just caught note of your thread...you say you've wired In the Harness Plug correctly. Both your former FC Alternator and Battery were okay prior to swapping In the FD Alternator. Where are you getting your readings from? Please do not use the stock Guage as an accurate Indicator. Go right to the source to determaine the output of your Charging System using a quality DMM. Should you find the readings consistent - have It load tested to determaine It's true output. Should this check out poorly, than PM me so we can get you cleared. But please - PM me regardless of the results.

I suspect that the Harness Plug Is wired In correctly just basing It on your description. How long have you been driving on your FD Alternator?

As for the s4 NA:

As for the s4 TII, as gathered by a fellow forum member:




As always should be done, besure to cut, solder, shrink tube and wrap your connections.

This Is how you wire In a FD Harness Plug Into a 86-88 stock Wire Harness. With the 89-91 stock Harness, this In not applicable due It having the same plug as the FD.

 

Didn't you tell me the same thign a few months ago, and I hesistated and said everything was fine? lol... just the effort of taking it to a shop to have it load tested is so... efforting. meh, im whining, its late.

I haven;t seen it above the 14 mark on the stock gauge since i installed the fd alt. I'll grab my multimeter tomorrow morning and get some results I guess.

 

will do as soon as I can

so far the car wasn't even driven
it was late at night so didn't have much of a chance since I had to drive by the house and wake everyone else up
but did let it sit and idle for a moment


will try to get a volt meter on it as soon as I can as well though I will be honest did just use the stock meter since it seemed fairly decent with the s4 alt
but prolly some time here in the future will just take it to the shop and have them test it out and see what they say


just curious can most places like schucks and such test the alt if it is not hooked up the car and tell me how it does?

also prolly do need to solder and shrink wrap them since all I did was hook them up with crimps for now

thanx for the help so far guys and thank you tony for standing behind your product

also out of curiostiy what should it read at during idle at 2000rpms and up?

 

Damn! The car hasn't been driven yet? You were using the stock Guage as an Indicator? Shame on you. Get In and drive.

 

if you search for info on alternators etc, you will find that people mention this bs advice quite often. i seemed to find it in quite a few threads.

 

Just drive the car a bit, its not lik you are going to go WOT. I also noticed that you just used crimps to connect the wires, thats might part of your problem as well. Get it solder and then check it out. I tend to see, depending on how many accessories are on mid 13's at idle with brake on and low to mid while crusing around 2500rpm. With all accesories on and brakes at idle I will some times see low 13's to high (12.8-9v)...

I still get dimming lights when I hit the brakes, when I am at idle...

 

Results

Engine off:



Right away after ignition (car already warm.) Idle: ~1krpm


Low beam lights


Highbeam + fogs


High + Fogs + Defroster on high, and hot


High + Fogs + Defroster on high, and hot, + Revving above 1.5krpm


High + Fogs + Defroster on high, and hot + Just after revving, and back down to idle

 

It was a common way to test an alt back in the 50's through 70's on domestic cars. Any real mechanic worth his salt knows better for modern internal regulated alternators.

Of course most of threads still suggesting this are by people that have read that it is the thing to do, rather than real world experience or are simple shade tree mechanics taught buy buddies, dads, or friends that really don't know.

I personally have seen BMW, Porsche, and a couple different Japanese cars spike to 16+ volts when that lame test as done (infact the BMW a 750, burned out the whole electrical system in the car when a guy did it at a stereo shop I once worked at).

 

Yep, looks like the alt is failing. Do you have access to a inductive ampmeter to see the output of the alt???

Of course double check the run and reference wires for the alt, to make sure you didn't hook those up wrong. There was quite a bit of bad info and posts (even websites) on wiring up FD alts into a FC.

 

really..? Its one of them from silverrotor... I guess I'll take it to the shop and get it tested... I'll contact silverrotor if something up i guess...

I just plugged the stock s5 harness into the s5 modified harness... (and moved the L post...)

 

Well with so much bogus posts on how to wire up the alt, it was pretty common to blow out the run diode

hell, there were idiots saying that you needed a relay when using a FD alt...

Makes me sad that so much incorrect info gets posted.

 

When I did mine, I merely connected the white/black stripe wire with the other white wire, and the black/white stripe wire with the dark red wire, everything worked fine. I know the whole top/driverside thing can be a little confusing as it isn't really the clearest thing in the world, but double check so that you have the correct wires hooked up and do solder them together, this isn't car audio here.

(BTW Silver, it's running like a champ. No dip at all in the guage with brakes/lights/heater/stereo and subs on all at once. Thanks and I'll catch you in Ottawa!)

 

I'm wondering if did get a not happy alternator. I get dimmed lights at idle all the time, its quite annoying to take the car out of gear to coast/brake to stop and the lights go dim... i dunno. If i get up early tomorrow I'll run to napa and see if they can run a quick test.

 

took the alt to schucks and they tested the alt and said it came back good
think the voltage was something like 14.6 or 14.06
know they ran 3 different test and I'm thinking one was voltage
another was voltage on load
and not sure what the third test was

but they couldn't tell me what that amps where



so guess it comes down to my wiring right now
will check those out as soon as I can since my car is about 16 miles from me right now and see what is going on


also out of curiosity what are those two wires for on the plug?

and which one is poss and which is negative? or is it a little different then taht?

 

NO!!!!!!!

One is for referance voltage from the ignition circuit, and the other is to tell systems in the car that the alternator is running.

S5 and FD (FD uses the non-turbo style connectors):


S4: