Nine Ball

iTrader: (38)

Just wiring up the engine and discovered that there isn't an LS1 alternator plug on the painless wiring harness. I can probably get that plug (one wire out) from the dealership, but does anyone know how I should wire it up? Where does that single wire coming out connect to?

66ImpalaLT1

Connects to the dummy light in the dash. I checked the factory wiring diagram for my '66 and found the appropriate pin on the regulator harness to splice it into.

My LT1 painless harness did not have this either.

Pro Stock John

iTrader: (34)

For my 98 FAST setup, we wired two 1000 kilo ohm resistors in parallel to mimic the bulb in the cluster and it charges fine. The 98 wire goes to keyed power.

Speartech

iTrader: (14)

The easiest way to hook this up with a 98 PCM is to go from the alternator to a 500 ohm resistor,and then from the resistor to a switched ignition source (key on 12 volts). You can use a dash lamp instead of the resistor if you want, but it needs to be a bulb and not an LED.

On the 99 and up PCM's, the PCM controls the LAMP line directly.

Uk Robert

Hi, I`m over in the UK and have nearly completed an LS1 install into Ford (Mercury) Capri. I have a similar wiring question. The original wiring of the Capri consists of 3 wires. 1 from the fusebox, 1 from the battery and 1 from the dashboard warning light. Am I correct in saying that the fusebox and battery wires can be bolted to the large terminal on the back of the Alternator? My reconfigured LS1 harness from Fuel Injection Specialities has the one wire hook up into the 4pin connector on the alternator which just leaves my capri dashboard warning light wire. Where does this go to? Does this have to be connected somewhere in order to "excite" the Alternator? Any help much appreciated as this is one of the last things holding me up!
The engine/pcm/loom are for year 2000 Camaro

Jones'n

On the 2000 LS1's, the ECM controls the Alternator, so the charging should be fine. However, the light in the dash will not functon properly, if at all.
The other 2 wires (battery and fuse box) should indeed go to the stud on the alternator.

Nine Ball

iTrader: (38)

So, in other words, that single wire is kind of an off/on switch for the alternator? What dummy light does it usually operate?

Speartech

iTrader: (14)

The "GEN" or "ALT" light.

Speartech

iTrader: (14)

The thing to note is that either a light bulb or a resistor is an important part of the circuit. Do not take a 12 volt line directly to the "L" terminal of the regulator (terminal "B" on the late style connector).

Uk Robert

Thankyou for the help. How can I get the dashboard light to work, bearing in mind there will be 3 unused connections in the 4pin connector on the alternator. Can one of these be used to go to the warning light?

Speartech

iTrader: (14)

If you really want the dash light to work, you would need to break the connection from the PCM and then wire the light in as described above. On the 99 and up, it will set a code, but won't affect anything.

No, the other 3 connections are for other functions, that aren't used in this application.

Uk Robert

Ok Thanks. I`ll do without the warning light but wire in a volt meter. At least I can now correctly get the alternator connected tonight!

Scooter70

iTrader: (1)

How would an ammeter be configured in this situation (with my 2000 harness)? My '70 gauge measures current not voltage. For now I want to stick with stock gauges, so if there's a way to wire it up so that I have an idea that the charging curcuit is working, I would like to do it. The original alternator had three wires in addition to the big wire going to the battery. (I'm not sure which one does what though...)

robin427

What are the other functions that the 3 unused connections are meant for?

I may have misinterpreted, but the single wire that runs from my PCM to the alternator is the exciter wire, yes? To cut this wire and connect a bulb into it would mean that the bulb would be turning on all the time, wouldn't it?

Speartech

iTrader: (14)

No, the bulb wouldn't be on all of the time unless there is a problem with the alternator. The bulb comes on with the key on but as soon as you start the engine and current starts to flow in the alternator, you have the equivalent of 12 volts on BOTH sides of the bulb, so it goes out. If you have certain diode or regulator failures, the light will come on, warning you of a problem.

The other terminals are not used in this application, and you shouldn't try and use them for anything, but they are:

S = the Sense lead. used to sense the charging voltage. It's done internally on our alternator.

L = Lamp terminal. This is the one used to turn on the regulator either thru a lamp, a resistor, or let the PCM do it on 99 and up applications.

F = Field terminal. Can be used to control the output by controlling the field voltage. Some applications let the PCM control this terminal.

I = I forget what this one even does . I don't think any applications use it that I know of.

robin427

So I can cut the red wire that goes from RED15 of the PCM direct to the alternator and put a bulb in between?

Brilliant!! Thanks for your help... don't go away just yet, though...

badjuju342

iTrader: (3)

Tony,which car are you doing the swap in? the Firebird? if so i'd very interested in comparing notes with you .