What is this?
Thread Starter
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Tuned
Joined: Oct 2020
Posts: 260
Likes: 12
From: Lakeville, MN
The two red wires with blue traces, with the jumper on the other side of the connector, are from the ignition switch to the “S” post on the starter relay/solenoid.
where is the “S” post on the starter relay selenoid?
where is the “S” post on the starter relay selenoid?
Lead Driver
Joined: Jul 2017
Posts: 9,579
Likes: 1,162
From: San Jose, CA
Does your truck have an ammeter, or an indicator lamp for the alternator?
If it’s like most, and has the ammeter that’s supposed to show the amps that the alternator is putting out to charge the battery and run the system (though they rarely work), then the White with black trace wire goes straight from the alternator’s STA post, up to the carburetor’s electric choke.
If it’s got the battery lamp instead of an ammeter, then it does split off and go to the voltage regulator.
With an ammeter, the regulator has three wires. With a light, the voltage regulator has all four positions filled.
If it’s like most, and has the ammeter that’s supposed to show the amps that the alternator is putting out to charge the battery and run the system (though they rarely work), then the White with black trace wire goes straight from the alternator’s STA post, up to the carburetor’s electric choke.
If it’s got the battery lamp instead of an ammeter, then it does split off and go to the voltage regulator.
With an ammeter, the regulator has three wires. With a light, the voltage regulator has all four positions filled.
Lead Driver
Joined: Jul 2017
Posts: 9,579
Likes: 1,162
From: San Jose, CA
Now that I look closer at the picture, I can see that the regulator looks to have four wires. That would mean you have the battery lamp instead of the gauge.
The orange wire in the first position marked “F“ runs to the alternator’s FLD terminal.
The second position marked “S” should be the white with black wire going to the alternator STA post.
The third position marked “A” is the yellow wire (possibly with a white trace) which samples the battery voltage directly from the large black wire.
The fourth position marked “I” is the green with red wire and runs straight up to the dash indicator lamp, and then to the ignition switch.
The orange wire in the first position marked “F“ runs to the alternator’s FLD terminal.
The second position marked “S” should be the white with black wire going to the alternator STA post.
The third position marked “A” is the yellow wire (possibly with a white trace) which samples the battery voltage directly from the large black wire.
The fourth position marked “I” is the green with red wire and runs straight up to the dash indicator lamp, and then to the ignition switch.
Thread Starter
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Tuned
Joined: Oct 2020
Posts: 260
Likes: 12
From: Lakeville, MN
So where does the green with black trace an “white” with black trace go? Also I don’t have an electric choke.
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Lead Driver
Joined: Jul 2017
Posts: 9,579
Likes: 1,162
From: San Jose, CA
I'll have to look up a Green w/black wire, but for a '78 truck I can pretty much guarantee that it came with an electric choke from the factory.
Maybe there were still some exceptions(?) but by '78 things were becoming more homogeneous with smog and reliability components. Electric chokes being one of them, and that fits both categories.
Is the Green w/black wire in your picture somewhere? Got a closeup?
And in some cases, we have to make assumptions on wire colors, since over the last 45 years or so, many wires may have faded.
Paul
Maybe there were still some exceptions(?) but by '78 things were becoming more homogeneous with smog and reliability components. Electric chokes being one of them, and that fits both categories.
Is the Green w/black wire in your picture somewhere? Got a closeup?
And in some cases, we have to make assumptions on wire colors, since over the last 45 years or so, many wires may have faded.
Paul
Lead Driver
Joined: Jul 2017
Posts: 9,579
Likes: 1,162
From: San Jose, CA
Oh, so answer your question though, if there was no electric choke from the factory, then the White with black STATOR wire goes straight from the STA terminal on the back of the alternator, up to the “S” terminal of the voltage regulator.
However, because electric chucks were so ubiquitous by then, there would have at least been a pigtail and connector going up somewhere behind the engine.
However, because electric chucks were so ubiquitous by then, there would have at least been a pigtail and connector going up somewhere behind the engine.
Lead Driver
Joined: Jul 2017
Posts: 9,579
Likes: 1,162
From: San Jose, CA
Yes, it does.
The black with red from the alternator, charges the battery and powers the vehicle through its almost direct connection to the battery there at the starter relay/solenoid.
The yellow wire is spliced to it and gives the regulator a direct reading of battery voltage. The A stands for “armature” in this case.
Green w/red to the ignition switch. Through the indicator. The I stands for either “ignition” or “indicator” or something similar. Don’t know for sure, because I have never seen anything written about what exactly the “I” stands for.
White with a black stripe runs between the STA post of the Alternator to the S post the regulator. A splice brings the other branch up to somewhere behind the engine to run the choke. The S is for “stator” in this case.
The orange wire runs between F position on the regulator and the FLD terminal on the alternator. This is the “field” wire tells the alternator how much to charge.
The black with red from the alternator, charges the battery and powers the vehicle through its almost direct connection to the battery there at the starter relay/solenoid.
The yellow wire is spliced to it and gives the regulator a direct reading of battery voltage. The A stands for “armature” in this case.
Green w/red to the ignition switch. Through the indicator. The I stands for either “ignition” or “indicator” or something similar. Don’t know for sure, because I have never seen anything written about what exactly the “I” stands for.
White with a black stripe runs between the STA post of the Alternator to the S post the regulator. A splice brings the other branch up to somewhere behind the engine to run the choke. The S is for “stator” in this case.
The orange wire runs between F position on the regulator and the FLD terminal on the alternator. This is the “field” wire tells the alternator how much to charge.