alternator connector re-wiring

[vex]

So I'm going through my stock harness right now and I have it pretty much laid out easy enough. From what I can gather thus far I can re-wire the stock alternator so it doesn't use the normal wires. My thinking is this (looking on 50-16 for those interested):

I disconnect the W/B wire completely. This means that the warning light relay will not kick on as it doesn't complete the circuit. I will then hook up the B/W wire to a switched 12V source (probably a relay or the old ignition fuse location). This ensures that the alternator will charge correctly and will not output an alternator warning light.

Are my thoughts correct?

Any other options people can think of?

[NoDOHC]

Actually, you need that warning light wire. The alternator gets the initial current to excite the fields from that wire (through the light). Without it, you are relying on the residual magnetism of the alternator to initiate excitation (may not be sufficient, especially because the control transistors are connected in a Darlington configuration).

I just added length to the factory wiring and connected the appropriate wires to the alternator.

It might work as you proposed (if the residual magnetism is high enough), but I would advise connecting both wires.

[vex]

I was thinking the initial excitation would be coming in the other wire of the EM-36. Is this not the purpose?

[vex]

Perhaps I should start looking for one wire alternators that can fit and work in the car...

[FRED]

Your series four car gets its excitation from the White/Black wire via the Alt Relays coil, inside the CPU. It does not get it from the idiot/warning lights. The Alt relay is powered by the METER fuse on your series four car.

Even if the excitation wire falls off the alt (not likely, just a scenario).......the alt will most likely self excite when the engine is rev'd quickly above say three grand or so. Then it will regulate in a normal manner IF the Black/White wire is installed (switched power).

See jpg for series four alt diagram.

What's the deal anyway? Why does not the white/black wire not exist in YOUR car? If it does not exist for whatever reason............splice a wire to the white/black AT the CPU plug for the excitaion wire for the alternator. Easy fix.

[vex]

Originally Posted by FRED

Your series four car gets its excitation from the White/Black wire via the Alt Relays coil, inside the CPU. It does not get it from the idiot/warning lights. The Alt relay is powered by the METER fuse on your series four car.

I think you're misunderstanding what I was inferring. If the coil is not charged than the alternator warning light does not light up, correct? There is another wire coming from the same power source, which is a switched 12V supply feeding in through the same plug, but not through the relay of the CPU. From my reading of the diagram it shows a diode internal of the CPU relay indicating to me that the only way that relay will close is if the alternator warning light wire (The White/Black wire) will complete the circuit to ground. Now in all possibility I could be reading this wrong, as I can't fully read the internal explanation of the alternator, but it seems to me if the White/Black wire connects to ground the warning light will light up indicating that no excitation of the coil is occurring. As it stands right now I believe bridging the 12V switched from the Black/White wire and the White/Black wire will allow the alternator to function without issue (besides the warning light from the CPU).

Even if the excitation wire falls off the alt (not likely, just a scenario).......the alt will most likely self excite when the engine is rev'd quickly above say three grand or so. Then it will regulate in a normal manner IF the Black/White wire is installed (switched power).

Ahhh, I see. So the initial excitation does occur via the relay. Does the relay circuit break after 12V excitation occurs? And is there any ill effects from bridging both the white/black and black/white wires to a 12v switched source?

See jpg for series four alt diagram.

What's the deal anyway? Why does not the white/black wire not exist in YOUR car? If it does not exist for whatever reason............splice a wire to the white/black AT the CPU plug for the excitaion wire for the alternator. Easy fix.

I'm installing a standalone EMS and feeding all wires concerned with the engine through a cannon plug. I would like to eliminate as much of the stock harness as possible, and that includes the alternator wires not concerned with charging. I may invest in a one wire alternator, however if I can get 'away' with using the stock one for awhile by simply re-wiring the connector I'll go that route.

[FRED]

Your misunderstanding me.......................the excitation power comes from the METER fuse. That power travels thru the COIL of the Alternator relay NOT thru the contacts of the alternator relay.

So now you have the alt relay in the CPU getting power on its plus side of that coil. The negative side of that alt relay coil now travels on to and thru the alternator regulator and finds ground in the alternator itself.

So the alt relay now has power on it and a ground so it pulls in and caused the Warning lights to come on on the dash.

Now you start the engine and the alternator puts out. Now what was/is the ground wire of the alternator relay has power on it that more/less matches the plus side of the alt coil so that causes the relay to relax and break the contacts that go to the warning unit which in turn makes them go out.

The warning light unit itself has zip to do with the excitation of the alternator.It's the Meter power passing thru the COIL of the alt relay that IS the excitation power for the alternator. Normally if you backprobe the White/Black wire with the connector connected to the alt and key ON........the voltage reading will not be batt votlage but approx 3vdc (bit of a voltage drop there from the batt voltage entering the alt relays coil).

I wrote too much this time.

[FRED]

I see no reason you won't still have the CPU 'cause it is tied to the turn signals etc and it's not part of the EM harness on the engine. So if you keep that CPU that means the alternaor relay is still active inside the CPU and all you have to do is run a wire/splice a wire to the white/black wire at the CPU plug to the alternators small connector to have normal alternator excitation.

With a haltech etc your losing the EM harness that the white/black normally runs thru on a NON TURBO car and that's why you'd run a new spliced wire from the CPU's white/black to the alternators small plug. IF the car is a TURBO car the white/black does NOT run thru the EM harness on the engine but thru the harness on the left side of the engine (that's the engine harness) . That's shown in the first jpg I attached.

[FRED]

About the SELF EXCITATION............what I mean is that there is residual magnatism in the rotor of the alternator and if you spin that sucker up high and fast that that residual magnatism will cause the alternator to self excite and put out. I don't recommend leaving the white/black off, just saying that a series four will put out without the white/black excitation wire being hot.

Some people say that you can run switched voltage to the white/black wires contact on the alt and things will be fine. I differ a bit on that .

Again.........whether or not the alt relay ever pulls in or not matters not. As long as the METER fuse (or other switched power fuse power) goes thru the COIL of the alt relay to the alt is what matters. It is INDEED looking for a ground to cause the alt relay to pull in and tell the driver the alt is not working.........but that is NOT the main reasone they have power going thru the white/black to the alternators field. It going there to excite the alternator so it'll put out.

Ah heck. Run a switched power to the white/black and have at it. The alternator will put out...........but if it were me........I'd run a wire from the white/black at the CPU plug to the alernator and make the system as factory designed. I mean you NEED the CPU anyway.

This a turbo or non turbo car??????????

[FRED]

*(Ahhh, I see. So the initial excitation does occur via the relay. Does the relay circuit break after 12V excitation occurs? And is there any ill effects from bridging both the white/black and black/white wires to a 12v switched source?***

I'm going to beat this to death...................remember, its power passing thru the COIL of the relay NOT power passing thru the alt relays contacts that excites the alternators field.

The alt relays CONTACTS are harmless things that do nothing more than put a gnd on the Warning lights to make them all come on and nothing more. Ignore the contacts of the relay and pay attention to the Coil of the alt relay and power passing thru the coil to the alt itself. Gone for now.

[vex]

Complete sentences helps illustrate your point much better than half-assing. Just sayin'.

Originally Posted by FRED

I see no reason you won't still have the CPU 'cause it is tied to the turn signals etc and it's not part of the EM harness on the engine. So if you keep that CPU that means the alternaor relay is still active inside the CPU and all you have to do is run a wire/splice a wire to the white/black wire at the CPU plug to the alternators small connector to have normal alternator excitation.

With a haltech etc your losing the EM harness that the white/black normally runs thru on a NON TURBO car and that's why you'd run a new spliced wire from the CPU's white/black to the alternators small plug. IF the car is a TURBO car the white/black does NOT run thru the EM harness on the engine but thru the harness on the left side of the engine (that's the engine harness) . That's shown in the first jpg I attached.

The car itself is non-turbo (at least it was until I decided I was turbo charging it). Which means that the Alternator Wires pass through the EMS harness. Thus the reason for this thread. Unless the computer does something to the initial excitation voltage that I'm unaware of I do not see any benefit in keeping the warning system (IE passing the voltage through the warning light relay). Since the internal structure of the alternator dictates when the charging warning light comes on or off based on the voltage of the switched 12v source matching or exceeding the initial excitation voltage I see no reason not to bridge both the Black/White and White/Black wires (the warning system is being replaced by the digital dash and stand-alone EMS). Since the voltage coming from the black/white wire will meet or exceed the initial excitation circuit, the function of the Alternator will not be impeded. That's all I needed to know. If however I'm reading the information wrong, help me understand.

Originally Posted by FRED

About the SELF EXCITATION............what I mean is that there is residual magnatism in the rotor of the alternator and if you spin that sucker up high and fast that that residual magnatism will cause the alternator to self excite and put out. I don't recommend leaving the white/black off, just saying that a series four will put out without the white/black excitation wire being hot.

Some people say that you can run switched voltage to the white/black wires contact on the alt and things will be fine. I differ a bit on that .

Again.........whether or not the alt relay ever pulls in or not matters not. As long as the METER fuse (or other switched power fuse power) goes thru the COIL of the alt relay to the alt is what matters. It is INDEED looking for a ground to cause the alt relay to pull in and tell the driver the alt is not working.........but that is NOT the main reasone they have power going thru the white/black to the alternators field. It going there to excite the alternator so it'll put out.

Ah heck. Run a switched power to the white/black and have at it. The alternator will put out...........but if it were me........I'd run a wire from the white/black at the CPU plug to the alernator and make the system as factory designed. I mean you NEED the CPU anyway.

This a turbo or non turbo car??????????

Why? You stated you wouldn't do it this way, but why?

Originally Posted by FRED

Your misunderstanding me.......................the excitation power comes from the METER fuse. That power travels thru the COIL of the Alternator relay NOT thru the contacts of the alternator relay.

So now you have the alt relay in the CPU getting power on its plus side of that coil. The negative side of that alt relay coil now travels on to and thru the alternator regulator and finds ground in the alternator itself.

So the alt relay now has power on it and a ground so it pulls in and caused the Warning lights to come on on the dash.

Now you start the engine and the alternator puts out. Now what was/is the ground wire of the alternator relay has power on it that more/less matches the plus side of the alt coil so that causes the relay to relax and break the contacts that go to the warning unit which in turn makes them go out.

The warning light unit itself has zip to do with the excitation of the alternator.It's the Meter power passing thru the COIL of the alt relay that IS the excitation power for the alternator. Normally if you backprobe the White/Black wire with the connector connected to the alt and key ON........the voltage reading will not be batt votlage but approx 3vdc (bit of a voltage drop there from the batt voltage entering the alt relays coil).

I wrote too much this time.

Alright, this doesn't make any sense to me. Are you stating that it takes only 3vDC to initiate the initial excitation of the coils (I'm not talking about the warning relay), or are you saying that the initial excitation voltage experiences a 3vDC drop (so instead of a 12.0v it sees a 9.0v).

Originally Posted by FRED

*(Ahhh, I see. So the initial excitation does occur via the relay. Does the relay circuit break after 12V excitation occurs? And is there any ill effects from bridging both the white/black and black/white wires to a 12v switched source?***

I'm going to beat this to death...................remember, its power passing thru the COIL of the relay NOT power passing thru the alt relays contacts that excites the alternators field.

The alt relays CONTACTS are harmless things that do nothing more than put a gnd on the Warning lights to make them all come on and nothing more. Ignore the contacts of the relay and pay attention to the Coil of the alt relay and power passing thru the coil to the alt itself. Gone for now.

I understand that. I was talking about the original circuit and keeping the alternator charging light off, while still being able to have a functioning alternator. As stated earlier the warning system will be superseded by the EMS warning system.

[FRED]

I wouldn't do it that way because if memory serves I'd lose the ability of the Alt relay in the CPU to pull in and light up all the Warning lights. Memory.

See the jpg attached? Red is from the switched Engine fuse power and if you look you can see that it will feed the field all by itself and more or less uses the same circuit as the power from the alt relay (Meter fuse pwr).

I find that picture out of the manual a little suspect in that respect. I may be wrong thinking so. One thing I remember when messing around was that if I fed batt voltage to the white/black terminal on the alternator, was that from then on I'd never get the Alt relay in the CPU to pull in and turn on all the idiot lights. I think some part of the internal regulator gets fried when doing that. What it is, is you lose the gnd in the alt that pulls in the alt relay when the alt is not turning.

That shouldn't effect you since your removing most wiring anyway and don't want stk functions like all the idiot lights coming on when the alt isn't putting out.

I'd just do what you suggested in your first two post i.e. splice a wire to the black/white to feed the terminal on the alt where the stk white/black goes and be done with it. You won't ruin the alt other than the circuit that puts a gnd on the alt relays coil to pull it in when the alt isn't turning.

Wrote too much.

[FRED]

Oh. About the excitation circuit...............the white/black is used for excitation AND for pulling in the Alt relay when the alt isn't putting out (the alt puts a gnd on the white/black when the alt is not spinning thur the internal regulator).

But when the alternator starts spinning and putting out power, the alt puts the output power of the alt on that white/black wire which in turn makes the Alt relay relax becase the plus side of that alt relay has batt power and NOW the neg side of that alt relay also has batt/alt power so the relay relaxes and that removes the gnd from the Warning light assy that WAS there when the alt relay contacts were *made*. Normal operation.

It's like the Engine Electrical section of the FSM says.............the white/black when connected to the alt should show approx 3vdc with key ON, engine OFF but when the engine is started that same white/black wire should show basically the output power of the alternator i.e. 13-14vdc.

So now you can see how the white/black will at times show just 1-3vdc with engine not turning and will show 13-14 with engine spinning. See ENGINE ELECTRICAL or is it electrical engine or is it body electrical???? one of the three.

Either run switched pwr to the white/black or just run one wire from the white/black at the CPU plug to the alternator.

I just realized .........I never see the ALT light in my Warning Light assy come on unless it's key on engine off. Never seen just the Alt light come on. At least not in my memory.

Heck I've never even looked to see which is the alt light in the warning unit. The just all come on when my key is on engine off and that pleases me enough and it never comes on when the engine has been running. Lucky me I guess.

I've played with this circuit in the past. Like remvoe the two wire connector and with key ON put the white/black to gnd and you can hear the alt relay in the CPU click and look and see the warning lights come all on to prove the alt relay and circuit are doing their job. So if one never sees his warning lights come all on with key on engine off, something to do to prove the alt circuit is the culprit is to so just what I described. IF all the warning lights come on you know the CPU and alt relay and wiring from the alt to the warning light unit are good and are just missing the gnd from the internal circuit of the alternator. IF the alt is putting out good one may decide to just forget about fixing the problem 'cause all you've lost is that one function of the warning lights assy. Big deal. Alt regulators can be had cheap for 25-30 bucks to fix that problem....EBAY

Wrote too much. Melandri just won first race of WSK. Bye.

[FRED]

Alright, this doesn't make any sense to me. Are you stating that it takes only 3vDC to initiate the initial excitation of the coils (I'm not talking about the warning relay), or are you saying that the initial excitation voltage experiences a 3vDC drop (so instead of a 12.0v it sees a 9.0v).


Missed that. If you pull the plug off the stk alt and look at the white/black with a meter you'll read batt voltage of approx 12vdc. Now hook it up the alt and backprobe the white/black with key ON. Should read 1-3vdc. The gnd in the alt pulls the voltage down from 12 to approx 1-3 vdc. See ENGINE ELECTRICAL SECTION of the FSM.

A alternator that never causes the warning lights to all come on with key ON engine Off will show 12vdc on the white/black wire with the connector connected to the alt..............proving the alternator is at fault for the lack of all the warning lights coming on under those conditions. So if that was someones case.........he'd just start the engine and see if the white/black when backprobed showed 13-14vdc with engine runing and decide whether or not it's worth fixing or ..........not. I've had this condition and spent the 25 bucks for another regulator and soldered it in to fix this minor problem.

[FRED]

See jpgs attached out of ENGINE ELECTRICAL.

I think I have one car still with a series four alt on it and I'm tempted to just go out there and pull the whtie/black out of the plug and jumper switched pwer to it to prove all you lose is the warning lights all coming on when key is on engine off. Tempted. One more WSK to go first.