Odd electrical runs from starter to alternator to junction block

[mattsk8]

I'm confident my truck is good now, but going to ask this one more time because I'm curious... The wire with the arrow pointing to it was missing on my truck. But the other schematic doesn't show that charge wire going to the battery at all. This was why it was confusing. Which of these is correct for 1986?

 

[DoubleDingo]

If you buy a 1986 shop manual you can stop the confusion. It'll have all of the wiring diagrams for every application. The manuals are online. Heck, the wiring diagrams are on this site if I remember correctly. The engineers are smart and stuff and knew what was needed to be added or deleted for each application, which is why there are variations from truck to truck and year to year.

 

[mattsk8]

I found my answer... The 6 cylinder in 1986 did not have that extra charge wire, but the v8 did have that extra charge wire. Here are the 2 different schematics. I was looking at the 6 cylinder schematic.

81-87 v8 engine schematic
81-87 l6 engine schematic

Things I'll never know... Why someone at some point decided to remove the charge wire that used to go to the battery on mine. Glad I solved part of the mystery.

The engineers are smart and stuff and knew what was needed to be added or deleted for each application, which is why there are variations from truck to truck and year to year.

From years and years of experience I know how things should be, that's how I knew there was an issue on my truck. I tried to find the schematic for this, and being new to this site I didn't know they were all right here, which is where I found the ones I just posted. In my original search I only found the l6 schematic (with no charge wire to the battery) and a later model schematic. You keep saying this about engineers in 1986 but I'm not sure what your point is; are you saying everyone should leave these trucks alone? Making this statement (over and over) doesn't help at all because regardless of what experience or degree an engineer at GM had back in 1986, there are better ways to do things in 2024. For example, adding relays to remove the amps from the switches on the power windows... "Engineers are smart" and all, but it's absolutely better to pull the amps from the switches in our trucks and instead just use the power window switch to trigger a relay.

And after I've added an amplifier, KC lights, air horns, halogen bulbs, a better ignition, etc... I would be threading the needle on the 10 gauge charge wire my truck should've had (but didn't) anyway, so regardless of what the engineer gods thought back in 1986, adding an 8 gauge charge wire is a better solution.

 

[DoubleDingo]

........And after I've added an amplifier, KC lights, air horns, halogen bulbs, a better ignition, etc... I would be threading the needle on the 10 gauge charge wire my truck should've had (but didn't) anyway, so regardless of what the engineer gods thought back in 1986, adding an 8 gauge charge wire is a better solution.

I am not discounting the use of larger wires. I am saying to keep the routing. If it wasn't hacked to begin with, upgrade it and move on.

 

[mattsk8]

I am not discounting the use of larger wires. I am saying to keep the routing. If it wasn't hacked to begin with, upgrade it and move on.

Mine was hacked and that was the whole point of why I posted. I was trying to figure out how it was supposed to be originally, so I could look at it and see what should be fixed and/or upgraded. My apologies if my original post didn't get that across.

 

[DoubleDingo]

Mine was hacked and that was the whole point of why I posted. I was trying to figure out how it was supposed to be originally, so I could look at it and see what should be fixed and/or upgraded. My apologies if my original post didn't get that across.

The beauty of dealing with old vehicles. You either get a gem or a turd. If it's a turd it's like every person that touched it wanted to ruin it. Then you get some gems where it's almost complete like it came off the assembly line.

 

[mattsk8]

The beauty of dealing with old vehicles. You either get a gem or a turd. If it's a turd it's like every person that touched it wanted to ruin it. Then you get some gems where it's almost complete like it came off the assembly line.

Aside from this one issue, this was actually a very original gem that came from Oregon originally. Everything including the radio was original. That's what led me to post, because the rest of the truck was so original that I assumed this must have been how GM did it. If I had to guess, the wire went missing because they swapped the battery cable and didn't get a cable with the extra wire going to the alternator, but that's a random guess.

 

[Jgonick]

You have to remember those wiring diagrams were for alternators/generators that came on the vehicle at that time.

notice the rpo codes on the diagram k81/k85 those are 66 amp / 37 amp the k64 means 115 amp

Also remember that how many amps the alternator actually puts out depends on your electrical load.