Alternator wiring?

[Tombo]

I'm about to drop in a vortec 350 from a 98 Chevy 1500 in my 84 k5. Swapped the intake for a carb setup. Im keeping the serpentine setup that came with it. Only problem I see so far is alternator wiring. The vortec alternator has a 4 pin connector. Is there a way to convert it to make it work? I've searched but haven't really found what I was looking for.

 

[Frankenchevy]

Is it a cs130?

 

[Frankenchevy]

If your going from a 10si to cs130 you can get acd #PT2145/GM#88861073

It has sensing wire and exciter wire. Plug and play simple. Then just run the BAT terminal to battery (+), starter solenoid or firewall junction.

To keep it simple, stick with wherever the bat wire is already going but ensure wire gauge is adequate.

 

[Snoots]

X2

 

[Tombo]

Is it a cs130?

No idea. Couldn't tell you the difference. All I know is it's a stock alternator for a 98. It's brand new so I wanted to try to use it.

 

[Frankenchevy]

Maybe it looks like this?

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[Frankenchevy]

And the old one like this?

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[gmachinz]

If its 1998 prolly looks like this:

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[Tombo]

Sorry it took so long to respond. Didn't realize the factory connector on the 98 is 1 wire. It was an oval shaped 4 pin connector but only had 1 wire actually in it. Got the engine dropped in, got a pigtail for the alternator out my works junkyard and connected it the 84s brown 'exciter' wire and she's charging fine. It'll have 14.25 volts at start up and after a few minutes it will drop down to about 13.8 volts. Assuming I don't need a resistor inline? Been driving it over the weekend and it seems to be doing its job.

 

[gmachinz]

I usually solder a 270-ohm to 330-ohm resistor on that brown wire when I supply the harness swap kits.

 

[C10MixMaster]

Sorry it took so long to respond. Didn't realize the factory connector on the 98 is 1 wire. It was an oval shaped 4 pin connector but only had 1 wire actually in it. Got the engine dropped in, got a pigtail for the alternator out my works junkyard and connected it the 84s brown 'exciter' wire and she's charging fine. It'll have 14.25 volts at start up and after a few minutes it will drop down to about 13.8 volts. Assuming I don't need a resistor inline? Been driving it over the weekend and it seems to be doing its job.

the resistor is built into the dash harness if you have gauges or runs through the idiot light that acts like a resistor.

 

[spanky55amg]

the resistor is built into the dash harness if you have gauges or runs through the idiot light that acts like a resistor.

Im going to piggy back off of thise thread if y'all dont mind.

I didnt even think about the gauge acting like a resistor. I have the pigtail with the resistor. And until my ground issue (another post) my CS130 has been running fine. I now have a new battery. And the alternator is now only charging at 12.4

So I checked, key on engine off, and I have 12.2 volts at the battery (fuel pump and fans were on, they are wired to ignition) and at the 4 pin connector, i have 12.2 on P and 12.15 on L. I have replaced the alternator and it still under charges. Whats the chances on getting a bad alternator? I mean, it should charge at 13+ if its getting battery voltage there, right? As long as the belt is spinning that alternator, it should be charging correctly? right? Im not missing something here, am I?

 

[C10MixMaster]

Im going to piggy back off of thise thread if y'all dont mind.

I didnt even think about the gauge acting like a resistor. I have the pigtail with the resistor. And until my ground issue (another post) my CS130 has been running fine. I now have a new battery. And the alternator is now only charging at 12.4

So I checked, key on engine off, and I have 12.2 volts at the battery (fuel pump and fans were on, they are wired to ignition) and at the 4 pin connector, i have 12.2 on P and 12.15 on L. I have replaced the alternator and it still under charges. Whats the chances on getting a bad alternator? I mean, it should charge at 13+ if its getting battery voltage there, right? As long as the belt is spinning that alternator, it should be charging correctly? right? Im not missing something here, am I?

Gauge is a completely separate circuit and has no effect on the alternator.

the D+ on a SI10 , SI12 is the equivalent of the L terminal on a cs130.

The D+ or L terminal is wired in one of three ways. 1. wired to an ignition source through a resistor wire (there is a special wire that has built in resistance) this is how GM wired the trucks that have a gauge. 2. wired to an ignition source through a charge light (idiot light) the light bulb acts as the resistor in the circuit. 3. wired to an ignition source through a resistor (Delco recommends 35-500 ohms)

The S terminal should be connected to the B+ post on the alt.

Disconnect the plug from the alt. check for voltage on the L wire. there should be voltage there with the key on.

New alternators are usually good, remans i have had 2 in arrow that were bad. If in doubt most parts stores can test an alt off the car.

 

[gmachinz]

With key on, engine off you want to see 12.4-12.5 volts. I’d be wondering about the battery itself.

If you have a fuel pump and fans going tho, it makes sense you’re seeing a bit of voltage loss since the amp draw with engine off is putting a huge demand on the battery. If you haven’t modified the engine harness to take advantage of the newer style charging system that is most likely your problem and will continue to be. The stock wiring route for charging was adequate when these trucks were new but adding more demands to the system is going to tax that stock harness design and the wiring itself over time.

 

[spanky55amg]

With key on, engine off you want to see 12.4-12.5 volts. I’d be wondering about the battery itself.

If you have a fuel pump and fans going tho, it makes sense you’re seeing a bit of voltage loss since the amp draw with engine off is putting a huge demand on the battery. If you haven’t modified the engine harness to take advantage of the newer style charging system that is most likely your problem and will continue to be. The stock wiring route for charging was adequate when these trucks were new but adding more demands to the system is going to tax that stock harness design and the wiring itself over time.

I have don’t the big three. I’m running 2 ga from the battery to all ground. Battery to starter. Battery to alternator. I ran 6 ga from alternator to junction.

I just replaced the battery and thought this was an alternator issue so I replaced that and the new one puts out the same as the old one.
The only other thing it could possibly be is belt tension, but I highly doubt it’s that.

yeah, that voltage is usually higher if those accessories do not run. I should have pulled the relays but I was being lazy.