LS conversion alternator wiring question

[chev-obsession]

I tried this in the ls swap with no luck. Any help is appreciated.

I have a 69 C10 I have put a 6.0 and my first time messing with efi stuff to this extent. I have looked over the wiring in the truck and double checked the electrical diagrams in the service manual but want to ask the people who have done this before to make sure I’m on the right track.

I moved the battery to the drivers side, and removing the ammeter and external regulator.... hoping to clean up some wiring since it won’t be used.

Can I remove the blue, white and brown wires completely (and de pin the brown wire from the bulk head in the firewall) cut and solder the red wire to go from the battery straight to the bulk head on the firewall (with a bnew blade style fin line fuse) and run a new say 8 gauge wire from the ls alternator to the battery? Hope that makes sense... just want to make sure I’m doing it correctly and don’t want my truck to burn down lol

[VetteVet]

The only way you can do what you are describing is with a one wire style alternator. You will have to have an exciter wire and a voltage sensing wire if you want to use an internally regulated alternator. Some of the later style alternators use an internal sensing regulator that reads the voltage sensing off of the large output wire terminal which is connected to the battery/ main terminal circuit. I believe 94 and later years have this feature.

Otherwise the exciter wire (usually the brown one) will be connected to the "L" terminal and the sensor wire usually Red, will be connected to the "S" terminal on the alternator. You should notice the terminals on the alternator will be labeled "P L I S" or "F S L P". The brown wire can be sourced from any key on power source but you must install an inline resistor recommended 85 ohm 5 watt to 300 ohm .5 watt to protect the alternator internal diodes and prevent feedback to the ignition circuit when the key is shut off.

Here is a simple wiring diagram I developed to illustrate this wiring to convert the stock OEM trucks to a newer CS alternator.







There will be other helpful answers so pay attention to them as well.

[chev-obsession]

Originally Posted by VetteVet

The only way you can do what you are describing is with a one wire style alternator. You will have to have an exciter wire and a voltage sensing wire if you want to use an internally regulated alternator. Some of the later style alternators use an internal sensing regulator that reads the voltage sensing off of the large output wire terminal which is connected to the battery/ main terminal circuit. I believe 94 and later years have this feature.

Otherwise the exciter wire (usually the brown one) will be connected to the "L" terminal and the sensor wire usually Red, will be connected to the "S" terminal on the alternator. You should notice the terminals on the alternator will be labeled "P L I S" or "F S L P". The brown wire can be sourced from any key on power source but you must install an inline resistor recommended 85 ohm 5 watt to 300 ohm .5 watt to protect the alternator internal diodes and prevent feedback to the ignition circuit when the key is shut off.

Here is a simple wiring diagram I developed to illustrate this wiring to convert the stock OEM trucks to a newer CS alternator.



Attachment 2001760



There will be other helpful answers so pay attention to them as well.

Thanks,

That's all great info, however the way I understand the LS series alternators are controlled through the pcm? Is this not correct? Which if it is correct that brings me to think the wiring for the externally regulated alternator are no longer needed period. Simply asking, please correct me if I am mistaken.

[VetteVet]

Yes you are correct if you are using the pcm i.e. for fuel injectors, ignition, engine temp etc. you will still need an exciter wire to the alternator.

[chev-obsession]

VetteVet,

The black wire with fusible link in your diagram, is that the factory wire that connects to the junction block on + battery terminal and feeds the ammeter?

Because the way I read the factory service manual wiring diagram, the black wire feeds the ammeter and brown wire comes out of the ammeter and goes to the alternator?

[VetteVet]

[ATTACH][ATTACH]Attachment 2002208[/ATTACH][/ATTACH]

Originally Posted by chev-obsession

VetteVet,

The black wire with fusible link in your diagram, is that the factory wire that connects to the junction block on + battery terminal and feeds the ammeter?

Because the way I read the factory service manual wiring diagram, the black wire feeds the ammeter and brown wire comes out of the ammeter and goes to the alternator?

_________________________________________________________________
Yes the black on the top feeds the ammeter via the dash plug at the 12 terminal and the lower one shown as white feeds the ammeter on the other terminal via the dash plug at no. 1 terminal. They both have inline fuses (4 amp) and they are both positive polarity.

The brown wire goes to the firewall block then to the ignition switch for key on power and connects with the accessory terminal 12 gauge brown wire shown below. The brown wire feeds the fuse panel key on side, heater switch, wiper switch, turn switch, etc.







NOTE: the brown wire to the firewall block converts to a 22 gauge brown/yellow stripe resistance wire (10 ohms) for the alternator exciter and it mirrors the charging light wire in the idiot light dashes. The factory used it as a backup in case the charging light bulb fails. They used it solely, in the case of the gauge dashes which you have.

You already know this but the viewers may not . the brown wire to the firewall plug originally went to the externally voltage regulator and continued on to the alternator as the white wire. the blue wire with it continued from the EVR to the alternator and served as the voltage sensor for the EVR and the field voltage for the alternator. What we are doing is merely using the brown wire as the exciter and the red wire to the alternator as the sensor/field strength wire for the alternator.

[LS short box]

On all the LS swaps I've done I've purchased an aftermarket harness. The aftermarket harness supplied the single wire to the 2002 Camaro type alternator. I use Fbody accessories.
I don't run the large gauge wire to the alternator from the battery. I run it from the large stud on the starter.
On the older hot rods I've LS swapped I have replaced the original vehicle wiring harnesses with Painless wiring harnesses because I just don't trust 50 plus year old wiring. Also keep in mind any late model alternator has about 3 times the output of the original alternator.

[VetteVet]

Originally Posted by LS short box

On all the LS swaps I've done I've purchased an aftermarket harness. The aftermarket harness supplied the single wire to the 2002 Camaro type alternator. I use Fbody accessories.
I don't run the large gauge wire to the alternator from the battery. I run it from the large stud on the starter.
On the older hot rods I've LS swapped I have replaced the original vehicle wiring harnesses with Painless wiring harnesses because I just don't trust 50 plus year old wiring. Also keep in mind any late model alternator has about 3 times the output of the original alternator.

I have heard of the painless harness and it's a good solution. I mentioned in my first post that the later alternators used the single exciter wire. In the stock vehicles with the computers I believe the computers sense the circuit voltage and adjust alternator regulators through the single wire.

I wonder when you run the alternator wire to the starter cable, how are the truck circuits fed from there. In the post 76 trucks the starter cable had 2 other large red wires with fusible links connected there and they fed the truck circuits. I assume the Painless harness has that feature.

[chev-obsession]

Originally Posted by VetteVet

[ATTACH][ATTACH]Attachment 2002208[/ATTACH][/ATTACH]
_________________________________________________________________
Yes the black on the top feeds the ammeter via the dash plug at the 12 terminal and the lower one shown as white feeds the ammeter on the other terminal via the dash plug at no. 1 terminal. They both have inline fuses (4 amp) and they are both positive polarity.

The brown wire goes to the firewall block then to the ignition switch for key on power and connects with the accessory terminal 12 gauge brown wire shown below. The brown wire feeds the fuse panel key on side, heater switch, wiper switch, turn switch, etc.

Attachment 2002202



Attachment 2002206

NOTE: the brown wire to the firewall block converts to a 22 gauge brown/yellow stripe resistance wire (10 ohms) for the alternator exciter and it mirrors the charging light wire in the idiot light dashes. The factory used it as a backup in case the charging light bulb fails. They used it solely, in the case of the gauge dashes which you have.

You already know this but the viewers may not . the brown wire to the firewall plug originally went to the externally voltage regulator and continued on to the alternator as the white wire. the blue wire with it continued from the EVR to the alternator and served as the voltage sensor for the EVR and the field voltage for the alternator. What we are doing is merely using the brown wire as the exciter and the red wire to the alternator as the sensor/field strength wire for the alternator.


Attachment 2002201


Attachment 2002209

Ok this is starting to make sense. Ive been working on the wiring in depth now. A couple things I’m stumped on....

1) The alternator I have is a 160 amp output and only has a 2 pin plug on the back, unlike the 4 pin style I wasn’t able to find any adapter harness with a built in resistor. I’m sure someone has used this alternator in our trucks. I don’t see a way to add the brown wire with a resistor. That being said, what do I do with the brown wire?

2) Right now I have the brown wire clipped off from the EVR (until I find its final home) also have the gauge cluster removed. The headlights, And blower motor come on when I connect the factory red wire to the junction block. Why is this happening?

3) I used ls1nova’s electric speedometer kit, so I got rid of the circuit board on the gauge cluster. I also added a voltmeter and clock. I am wanting to terminate the black ammeter wires completely. Also removed the brake and temp warning lights in the speedometer. Am I ok to leave the wire that connects to the proportion valve. Or terminate it?

Any help is appreciated

[starterman99]

The Alternator you are using is an ECM controlled alternator. Delco RVC type.
If you don't have the right computer and other parts of the system you should change the alternator out for the non computer controlled style.

[lutronjim]

Kinda high jacking tread a little.

Vettevet

Why does most every thing show the sense wire as being heavy gauge?

To me it just serves so the alternator can 'see' the voltage at a point where most of the vehicle is fed from to enable the alternator to raise or lower output to keep it correct.

To me it could be 22 gauge and work fine - alternator needs to just see voltage not power.

Thanks

[jjzepplin]

I would like to see the results So I am tagging along.

[VetteVet]

Originally Posted by lutronjim

Kinda high jacking tread a little.

Vettevet

Why does most every thing show the sense wire as being heavy gauge?

To me it just serves so the alternator can 'see' the voltage at a point where most of the vehicle is fed from to enable the alternator to raise or lower output to keep it correct.

To me it could be 22 gauge and work fine - alternator needs to just see voltage not power.

Thanks

The answer is simple.
The sensor wire serves two purposes. It senses the downstream circuit voltage of the system and tells the internal regulator to adjust the current flow to the alternator fields. If the circuit voltage is lower than 13.5 at idle the regulator closes and allows more of the sensing wire current into the alternator and conversely if the voltage is higher than 14.5 the regulator opens and allows less current.

Because it carries more current than the exciter wire, it needs to be a little larger than the exciter wire. The OEM alternators are regulated differently and they are wired differently inside so the wire size wasn't as important. Plus the output is less so the field current doesn't need to be as much.

[gmc684x4]

This is for the non computer controlled Cs130/144 alternators
the non computer controlled alt has 4 pins

worst case you can change the headlamp harness to 69 72 upgrade harness and use EC82 Adapter with resistor (napa)

I do not know what wire diagram to look at for a ecm controlled alt

brown wire in your circled picture is for brakes

Diagram note brake light loss pressure wire I placed in the wrong spot look at diagram lower down

[jjzepplin]

vettevet?

[gmc684x4]

I made a mistake the brake wire goes in the engine wire harness plug

from what I read a bit some computer controlled alternators are wired to the BCM Body control module

If your ecm is not able to control the alternator the easiest route is to switch to the non controlled CS130/144

[gmc684x4]

Is this the brown wire you to to the Alt ?
it is brake loss of pressure switch light for your dash

[VetteVet]

Originally Posted by jjzepplin

vettevet?

Not sure what you are asking or how I should respond. I have been trying to determine if the ECM alternators will work with the brown wire used as the exciter but have not found definite evidence so far. I know that some of the four pin alternators P L I S and S L F P can be modified to work by using the brown wire like has been pointed out.

[lutronjim]

I have a GM 'connect and cruise' package in my 70ss and the harness has a wire marked to go to the alternator. I also have the VA one belt system that has a 4 wire TuffStuff alternator. I am running it with the GM supplied feed,

Problem is that it only that the computer only supplies 4v at idle. I have to go past idle to keep lights etc from dimming. I am going to change back to original 'brown' wire method after I confirm its OK with TuffStuff.

[chev-obsession]

So I ended up doing a lot of research and did trial and error stuff. I finally got it all figured out and buttoned up. This is what I did and hope it helps someone in the future.

Since I had a 2 pin regulator on the alternator there was no room to add the brown wire in. My options were to get a 4 pin alternator, swap the 2pin regulator for a 4 pin or remove the brown wire entirely. I also didnÂ’t want to buy a new wiring harness for the truck since my harness is in good shape, so thatÂ’s why I went this route.

Before making any executive decisions, I made sure the alternator was charging WITHOUT the brown exciter wire connected to the alternator. With a volt meter, I checked the battery voltage while the engine was off, it was a little low at 12.65 volts. Started the engine, turned the lights, wipers, radio... every electrical item in the truck was on, checked again with the volt meter and indicated the battery was being charged with 13.66 volts and slowly climbing, I think it stopped around 13.8. So I knew the alternator was being told to charge and was charging the battery and keeping up. With that being said IÂ’m now leaning towards removing the brown wire to clean things up.

With the key on, the brown wire as labeled above, would light up the test light. (Obviously) next a continuity test from the brown wire in the engine bay to the brown and white wire in the back of the ignition switch.

After removing the ignition switch harness from the back of the ignition switch, the brown wire has continuity with the brown/white wire on ignition switch side. Perfect itÂ’s looking good at this point. I removed the packard 56 terminal on the ignition switch side and re checked continuity and with a test light. With the brown and white wire separated from the power source at ignition switch and key turned on, no power was detected at the brown/ white wire and brown exciter wire in the engine compartment.

Re crimped a new packard 56 connector onto the big brown wire for ignition switch power terminal and bend the brown/white wire around itself and heat shirked it to prevent it touching another wire by chance, then removing the brown wire (to alternator) as well as the brown wire to the brake pressure switch from the engine compartment bulkhead.

While I was in there after upgrading to a voltmeter I did the same tests on the ammeter wires and decommissioned those wires as well.

Everything seems to working correctly.

Hope this helps someone in the future and hope my post makes sense.

[chev-obsession]

I forgot to mention the whole reason in doing this was so I could eliminate the “brake” and “temp” warning lights since I converted to the electric speedometer for the LS swap like ls1nova71 does.

[jjzepplin]

I would think you might want to keep the brake warning light. I have mine hooked up to the emergency brake as well so that it can tell me I have left it on and that is the bad smell... HAHA. It also sends a signal to tell you that your proportioning valve is having issues and possibly a loss of fluid has occurred. Sorry if I missed something.