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1974 K10 Dirty Sancho

Saved from cruel and unusual punishment
Overview Gallery Discussion
Alternator Wiring

The Gen VI 454 has a CS144 alternator so I need to convert the wiring from the 10SI/12SI to the CS144. I'm not too familiar with this conversion however I've found some chatter about some trucks having a battery light on the cluster and those that don't have the battery light need to add a resistor. This truck has a Amp Gauge and based on some comments it looks as if this pigtail with the built in resistor will work?
https://www.amazon.com/ACDelco-PT21...t=&hvlocphy=9032515&hvtargid=pla-571302583645

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I'd yank that ammeter out of the cluster. It's nothing but a potential fire starter. On my '75 I popped the clips out of the back of the cluster that connects the ammeter to the printed circuit. I took a voltmeter and added wires to the studs on the backside of it. One wire to the fuse panel, other to ground. The gauge gets held in with a screw anyways so not having it clipped to the back is ok.

On both of mine ('75 & '91) we reused the stock alternator wire and swapped on the correct connector pigtail for the cs144.
 
ZooMad75 said:
I'd yank that ammeter out of the cluster. It's nothing but a potential fire starter. On my '75 I popped the clips out of the back of the cluster that connects the ammeter to the printed circuit. I took a voltmeter and added wires to the studs on the backside of it. One wire to the fuse panel, other to ground. The gauge gets held in with a screw anyways so not having it clipped to the back is ok.

On both of mine ('75 & '91) we reused the stock alternator wire and swapped on the correct connector pigtail for the cs144.
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and no resistor?
 
skunked said:
and no resistor?
Click to expand...
No. The '91 had the volt gauge stock, so no gen/alt light. No resister installed. Been running the cs144 alternator on it for 5 years with the 5.3 and popped it right on the 8.1 when we swapped it.

The '75 had the ammeter but I don't remember if it had a separate gen/alt light. But we didn't add a resistor to the circuit to the new alternator. We moved the harness from one side of the intake to the other since the serp drive put it to the driver side.
 
ZooMad75 said:
No. The '91 had the volt gauge stock, so no gen/alt light. No resister installed. Been running the cs144 alternator on it for 5 years with the 5.3 and popped it right on the 8.1 when we swapped it.

The '75 had the ammeter but I don't remember if it had a separate gen/alt light. But we didn't add a resistor to the circuit to the new alternator. We moved the harness from one side of the intake to the other since the serp drive put it to the driver side.
Click to expand...

I’ve read lots of people saying the same thing and others claim you should add it.

here’s an explanation I found:


All late-model alternators employ an electronic voltage regulator. If your car is like this Chevelle and has a voltmeter or factory ammeter gauge without a charging system warning light, a resistor must be wired into the warning light circuit. Essentially, the resistor takes the place of the load created by the warning light.

We were curious as to why this resistor is important, and according to Painless engineer Eric Cowden, “The resistor limits the amperage the exciter wire can supply. In factory applications, either a charge-indicator light or ECM provides this 1 amp or less, switched 12-volt source. Without this resistance, too much amperage reaches the regulator and causes it to burn up.”
 
skunked said:
I’ve read lots of people saying the same thing and others claim you should add it.

here’s an explanation I found:


All late-model alternators employ an electronic voltage regulator. If your car is like this Chevelle and has a voltmeter or factory ammeter gauge without a charging system warning light, a resistor must be wired into the warning light circuit. Essentially, the resistor takes the place of the load created by the warning light.

We were curious as to why this resistor is important, and according to Painless engineer Eric Cowden, “The resistor limits the amperage the exciter wire can supply. In factory applications, either a charge-indicator light or ECM provides this 1 amp or less, switched 12-volt source. Without this resistance, too much amperage reaches the regulator and causes it to burn up.”
Click to expand...

I don't disagree with the theory. But with my '91 specifically, the wiring to the alternator is 100% stock except for the plug change to match up. The CS144 is charging like it should even with the load of two batteries on it for 5 years and counting.

Running it with the resistor isn't going to hurt anything either. If you got the jumper harness with the resistor already run it.
 
ZooMad75 said:
I don't disagree with the theory. But with my '91 specifically, the wiring to the alternator is 100% stock except for the plug change to match up. The CS144 is charging like it should even with the load of two batteries on it for 5 years and counting.

Running it with the resistor isn't going to hurt anything either. If you got the jumper harness with the resistor already run it.
Click to expand...

I just got the pigtail, I’m not going to worry about it for now.
 
skunked said:
based on the schematic @Truckman4life posted I don't see the tan wire on the 74 harness.

View attachment 360398
Click to expand...
I was looking at the 16B-105B circuit. They're calling it "brown" not tan. I figure given the age, it's probably close enough. It is a dashed line further along in the diagram which I think means optional. Maybe that's why it's not in the other diagram.
 
mrk5 said:
I was looking at the 16B-105B circuit. They're calling it "brown" not tan. I figure given the age, it's probably close enough. It is a dashed line further along in the diagram which I think means optional. Maybe that's why it's not in the other diagram.
Click to expand...

I have that wire and it’s tied together with the red wire with a ring connector and joins the 12v from the battery at the starter.
 
The gas tank is plumbed and ready for fuel.

I forgot the TBI tanks have the 1.75" filler and the bed was setup for the carb tank with the 1.5" filler. I found some 1.75" fuel filler hose and a 1.5" to 1.75" aluminum adapter that's commonly used for as a radiator hose reducer on LS swaps.

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I ended up buying the CS144 to 10si/12si wire adapter with the built in resistor for the alternator. Super easy install, just had to extend the 12v output wire since the adapter added a little length to the alternator harness.
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I went ahead and used a Seals-It two piece firewall grommet and ran all the Pro Flo wiring inside the cab along with the ECU. I also ran a signal wires for the oil pressure sensor and the coolant sensor for the autometer gauges.

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Ran a few other misc wires and plumbed the heater core hoses.

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Even easier to add oil with the cover off. Going forward I’ll have to use the breather or PCV opening.
 
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