Question for all who have put FD Alternators in FC's
 

Do your idiot lights still light up when you first turn on the key?

I've done one in an S4 and one in an S5. Idiot lights lite up initially in both, but now in neither.

In theory it's just an on/off switch from the alternator to light the lights. So what could go wrong inside the alternator if that's where the problem is.

But I wanted to check with the community before I started digging for where ever the bad connection is.

mine do not. it is an s4. let me know if you figure it out

Sometimes. I would say that maybe 20% of the time they all light up, but mine did the same thing when it still had the S4 alternator on it. I checked mine off to the FC electrical grimlins. The only thing wierd mine does is after start up it charges at like 11.5 volts until i tap the throttle and break about 2000 RPM and then it kicks up to 14.8 volts.

My warning lights are on if the key is on but the engine isn't spinning.

That's what I'm talking about. How long have you had your FD alternator in your FC?

Pull the body ecu out ( in the drivers side kick panel) and check all the solder joints where the harness plugs into it at. This contains the relays that control the dash idiot lights, the alternator charging circuit, and horn and door buzzer relays. I just de-soldered each pin and put down down all new solder and it fixed all of those issues. Idiot lights all work now, horn works, door buzzer works, and the car starts charging at 14.1 volts as soon as it starts up. I used to have to rev up my car to 2-3 grand to get it to self excite to start charging.
When you take it out and pull it out of its plastic cover you will see that most if not all of the solder joints in there are cracked and not making contact.

If you looked at the largest plug of the "CPU" and w/key to on put a ground to the White/Black wire and all the warning lights except the brake light will light up (unless the parking brake is engaged and thus "all" lights will turn on). If it does not then Alternator Warning relay is damaged or the wires to this relay are not mating properly or the Yellow/Blue wire running from the relay to the warning light box is not connected to the box properly.

thanks

boosted. Something is wrong with your alternator as the field is not energizing. By revving it up you are basically self energizing it.

I have all the idiot lights work normal. When I mistakenly left the sense wire off it charged at 15 volts and all the lights stayed on.

About a year. Has been trouble free.

Round one. Got into my S5. It was the alternator. I put a ground to the white/black wire at the alternator, idiot lights lite right up. Put in a replacement FD alternator, idiot lights lite right up albeit a bit dimmer than with a direct grounding.

Tomorrow, round two - the S4 gets checked out. I hope its cure turns out to be something as simple as the S5's cure.

dont. look in second gen archive and do the taurus alt. mucho better

Well, I once again have idiot lights. It wasn't the lights I was concerned about so much as the relay in the CPU seeing a ground signal. I'm suspicious that not seeing the grounding signal has been a cause of a battery drain issue I've been trying to figure out. Remind, this is using FD alternators in both cases.

S4 - Cause was a broken wire buried in the two wire loom that comes out of the alternator itself. A little solder and shrinking tubing, and the idiot light popped right on nice and bright.

S5 - Bad alternator not sending out a grounding signal when at rest. Replaced the alternator with new, lights light up. Although, oddly, they light up dim such that they really can only be seen at night. If I put a direct ground at the alternator plug, they light up brightly. Tried another new alternator, same dim lights. So the ground signal provided by the alternator is weak.

Not sure what's going on here, but unless someone can see another way to cure, I see a bosch relay supplement to the circuit in my future.

How 'bout trying this. Leave all the plugs on the alternator. Key to ON engine OFF. By hook or crook put a meter on the L terminal of the alt. The voltage should be 1-3vdc. What do YOU get when doing that? I've used a sewing needle to prick the insulation of the L wire to do this.

Or you might try this. Remove the batt neg terminal. Pull the small plug off the alternator. Meter on ohms. Neg lead to the body of the alternator. Positive lead of the meter to the L terminal blade on the alternator. Should read ?? about 2-4 ohms. What do you get. You NOT looking at the elect plug on the harness but the L blade on the jack of the alternator itself when doing this.

Sure you've got the L terminal not confused with the R terminal????? L terminal should be the one furthest away from the B termianl on the alternator. Or another way to look at it: when looking into the alternators small plug and viewing the keyway for the elct plug at the top........the L wire should be to your right and R terminal to your left as you look into the jacck on the alternator.

^ I was hoping my "unless someone can see another way to cure" comment would grab your attention Hailers.

Thanks. I'll follow your advise and check it all out. It will be interesting to see what readings I get compared to what your suggesting I should see and report back to this thread for future readers reference.

Again, the odd thing is putting a direct ground to the plug, idiot lights are nice and bright. The alternator is obviously quite grounded to the engine via the two mounting points. So something really seems to be going on with that grounding making it's way through the regulator.

I promise I don't have the L terminal confused although I get where you're coming from. If I was grounding to the R terminal, the test wire would get a little warm if not pop the fuse first since it runs directly to the battery positive. Not my first rodeo. :)

Sorry we never got the chance to hook up when I was in Dallas all last year.

"Sure you've got the L terminal not confused with the R terminal?????"

Remind, this is an S6 Alternator in an S5. As such, there is no "R". I do have an "S" which is easy to confirm since it gets a constant 12 volts.

Oh, ok. You've a L and a S terminal and the S is constant 24/7 power.

But the L wire should show approx 1-3 vdc with key ON engine OFF. .....with all the plugs attached to the alt and the L wire being backprobed with a meter.

This little 1-3 vdc checkout is in the series five and six manuals online. Engine Electrical sections. Also in the series four Engine Electrical.

The L wire is what is Excitation voltage and should NOT be batt voltage but should show 1-3 vdc with key ON engien OFF.

Jpg attached named Excitation is from the series five FSM. Series six should be the same. I did not look.

I'd also do the bit I mentioned earlier where you take the plug off the alt and probe the L terminal/blade with a meter on ohms and see if it reads ??? 2-4 ohms give or take just a little. Key OFF and out of the ignition and might be a good idea to remove the neg terminal off the battery prior to this.

Thanks. Will be my weekend chore.

All considered, I'm still puzzled why the idiot lights are bright with a direct ground at the alternator plug and dim when receiving ground signal from the alternator. Dim even when I make a supplimental connection from the negative of the battery directly to the alternator housing. And same symptom with three different new FD alternators.

Tried a different idiot light cluster, same dim lights.

Voltage drop probably. The S4NA & S4 vert run the alternator wiring through the Emission Harness, to the Front Harness and then back to the Engine Harness. T2's alternator wiring is entirely in the Engine Harness.

What I'd do is extract all of the alternator wiring and run it directly to where it goes, exactly like the T2 does to eliminate all of the unnecessary failure points.

Good suggestion, but this is about what's going on in my S5 Vert. Not my S4.

I have the same FD alternator in my S4 and the idiot lights light up nice and bright as one would expect. The S terminal plug has been wired directly to the battery positive as required. Wire for the "R" has been properly sealed off although if ever I need an IGN 1 switched postitive source for something under the hood in the future, I know where to find it. :) Anyway, all is good on that front.:icon_tup:

I'm going to put a stock S5 Alternator in the S5 Vert this evening to see how it affects the idiot lights.

Thanks to my friends at Lucky 7 for the loan and assist to that end.:icon_tup::icon_tup:

Update
 

I dropped in a stock S5 alternator, nice and bright idiot lights. Put the FD alternator back in, dim idiot lights.

Had both alternators checked out. The only meaningful difference was (surprise surprise) Lamp on Volts. The S5 measured .74 volts, the FD measured 3.16 volts. Both are relatively within tolerance (FSM 1-3 volts as Hailers indicated) but clearly the extra leakage into what is supposed to be a ground signal is the issue.

I've pulled two new FD alternators from O'Reileys. Both measured lamp on voltage at 3 volts .

I pulled a new FD alternator from Autozone. It measured lamp on voltage at 3 volts.

Has anyone else purchased FD alternators from these two for their FC (or FD for that matter) and run into this dim idiot light issue?

Final chapter, pulled one more FD alternator. .75 volts and nice bright idiot lights. So, clearly a bad batch of regulators in that earlier run.

So there you go archives.

I went through 3 alternators before I found one that actually worked "half assed".
2 used,one NEW(the new one gave up,And died).
Ya,I am thinking that they just didn't care about quality on this part!

Holy thread ressuuuuurrecttttion :)

Took me a while to find some thread like this ;)

ok, I got an Alternator off Ebay(yea, I know) from ACE Alternator, someone here have them before and said they're good, so yeah, I got one, said it was reman and upgraded to 140amp.

Ok, installed, dimmed idiot light when key to on engine still off. I remember when I had the original alternator, which clearly fails at charging (less than 12 V!) had really bright light

I wonder if this Alternator is broken. I know I can test it but after reading HOZZMANRX7's results, I think I might have a "bad" Alternator cuz all my idiots lights were dimmed(before the engine start, just key on)

I probably gonna yank the CPU out and resolder everything first, right ?

Any inputs anyone ?