Studying the schematic

[Raider L]

@SquareRoot,

NAPA has one. A reference said the wire gauge is supposed to be 4 sizes smaller than the wire it's protecting. NAPA has a #16 gauge with the fusible link in the middle. I'll go get that tomorrow, but I have to start on my Christmas cards I send out every year. I send out over 40 Christmas cards every year!

Merry Christmas to everyone here at GM Square Body!!!

 

[Raider L]

@Ellie Niner,

You know what I just realized??? You know that nasty looking wire that was attached to the Alt. wire? If you read what me and @SquareRoot have been talking about where I need another fusible link up on the junction block because the schematic shows two fusible links, one on the #10 wire going to the solenoid, which I have, and another one on the Alt. wire on the junction block, which I don't have. Well guess what? If you go back to those pics you'll notice that the light blue wire that was so badly soldered to the red wire coming from the Alt.......that WAS the fusible link!!!! Instead of putting in a real fusible link they just badly, and bearly soldered the Alt. wire to that light blue wire! Isn't that something? I had a fusible link on there and didn't know it. Well, I wouldn't have trusted that for nothin' !

You have to go all the way back to my "Amp Gauge Install" to see it, at least one of those pic's that's in that group.

 

[Bextreme04]

@Bextreme04,

That's exactly the same schematic I'm using! That's the factory schematic, but the wiring changes for trucks with A/C. That's what messed me up. I kept looking for this wiring that had different colors than what I was looking at in my truck. Here's the schematic I found on line. But, since I don't have any ink in my printer I had to hand draw it. But it's accurate. If you'll look on it near the bottom it shows the junction block and the #10 orange wire is not on it. There's a #10 red wire? That #10 orange wire is shown going inside and goes to the fan speed switch. But the colors are correct for what I see in my truck now. Some of this wire is on your and mine schematic and some isn't. As far as fusible links in the start circuit, I don't know what to say. The ones down on the starter you see in the above pics are the only ones that have ever been on the truck. It's never caused a problem so....? And that orange wire with the 20 amp fuse on it? It was like that when the A/C was in the truck, so I left it like it was. I guess it was put there at the factory because it was part of the A/C. Why? I don't know anything about A/C circuitry. But today I did switch that #10 starter wire to the side of the junction block this schematic shows it. So it's on there now. But so is the #10 orange wire!
If anyone wants to make a copy of this A/C schematic please feel free to do so.

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That is the different wiring for AC on the one side of the junction block, but the engine and firewall wiring is still the same before the junction block on AC trucks. My truck matches that wiring. Your wiring looks to have been hacked on both sides of that junction block and is in no way what it would have been from the factory... that's what I've been trying to say. You can see that the fused wire is a cheap auto store inline fuse holder that has been spliced into that wire. I bet whoever added that cut out the fusible link or it had blown and they replaced it with a fuse. Are you the original owner of the truck?

 

[Raider L]

@Bextreme04,

No, I'm the second owner, but I was the one who put that 20 amp fuse holder on there but it replaced one of those big twist together fuse holders and I didn't like the looks of it so I put the one you see in there. The big twist together fuse holder that was originally there had a 20 amp fuse in it. So I replaced it with one of the modern kind. I thought the one I put in there looked better and wasn't so big and scetchy looking like it was. Like it really stood out right up there on the firewall and I didn't want the first thing people's focus went to was that big a** fuse blond colored holder. Lol. But that's the way it was when I bought the truck. It's like I've been saying, I've not removed or added anything except that phenolic block I put up there under the junction block to split the starter wiring so I could remote start the truck.

Like I said to @Ellie Niner that the ugly twisted together half way soldered wire I found in that old taped up Alt. wire at the junction block was like that when I bought the truck. And when I untaped it I found the #12 red Alt. wire and a #14 light blue wire that had the insulation striped off long, and the Alt. wire to, and it was twisted together loosely and had a dab of solder on it. But I know now that WAS what GM, or somebody at some time considered a adequate fusible connection for what the schematic was showing. I cut that mess out the other day and soldered a #10 splice onto the Alt. wire and connected it to what you see in the pics above. Now that you have pointed out that there needs to be a real fusible link there( that's what led me to realize what I cut out WAS the fusible link), I will put a real one on that Alt. wire at the junction block. And that ought to fix everything to what it shows on the schematic it should be.

Other than the A/C wiring that's up there, when I removed the A/C evaporator box off the firewall I had to do something with the fan relay box, that little box originally mounted on the side of the evaporator box. I just took it off the evap. and put it on the inner wheel well below the blower motor. And Ill take a pic of it and you can see that the colored wires going to it are the wires it shows in the schematic. Once I realized the colors were the ones that go to the A/C, then they made more sense. I couldn't figure out how the blower motor had a #10 purple wire going to it when the schematic only showed a #14 orange wire. But with A/C the blower motor has a #10 purple wire going to it from that relay box. So it's all correct. The #10 orange wire is power for the blower motor, and it goes into the relay box and the #10 purple wire comes out of the relay box up to the motor, and the #16 orange wire goes to the switch. #16 black is ground as the schematic shows.

 

[Raider L]

@Bextreme0

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The pic above is of the fan relay box that is usually on the side of the evaporator box of the A/C. You can see that there is a #10 purple wire to the blower motor, and that #10 orange wire, I guess is the power for the fan in the A/C configuration. That schematic I drew shows it. The #16 orange wire goes to the fan switch, and the #16 black wire is the ground wire attached to the firewall, as shown in the schematic I drew, as a "sheet metal" ground.

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You can see the #10 purple wire going to the fan, the plug going into the fan mounting plate behind the vent tube or whatever that tube is. I assume it goes to the fan from there.

 

[Raider L]

@Bextreme04,

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Here's what was up on the junction block that I replaced with that modern type fuse holder. Now, isn't this gaudy? I wouldn't want that thing sticking out in every bodies face when I was showing my truck. To me, that looks cheap!

 

[Ellie Niner]

@Ellie Niner Here's what I was referring to in the above post.

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This is a closeup of the number on it. I'm sure I have the info on this little thing, but it's in my rebuild notes and stuff and I'd have to do some digging to find it. It's not a "shunt" I don't think. I don't recall names of electrical things like this. It has a "value".

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In the above pic you can see it near where I'm pointing. In the pic I'm pointing to another wire but you can see it in one of the wires going down to the starter.

That's a diode. It functions like a check valve, letting power flow one way, but not the other. It appears to be a (pretty healthy sized) Schottky diode, which tends to be more efficient than a standard PNP diode.

 

[Raider L]

@EllieNiner,

Man you're specking Greek to me. So is what the Autometer guy, or maybe it was the MSD tech guy told me about it's protection of my electrical system, so is it doing what he said it would do, not letting juice left over from the power of the mini starter come back up the wire and negatively affect the wiring in the rest of the system? I'm not having any kind of a problem with it or anything. I think I got it from Radio shack. I just ordered a roll of solder from them. I thought they were gone, but apparently not. They just don't have any stores left, to much overhead.
So why didn't the trucks come with that built in? I think his telling me about putting it in had something to do with the MSD 6A multiple spark box, to protect it more than anything else.
Can I use those numbers on it to get another one? And how would I know it's gone out?

 

[Raider L]

@Ellie Niner,

I looked up that diode and it says that it's a"silicone high current rectifier diode", "Schottky type" whatever any of that means. I've seen the "Schottky" site but it was so alien I couldn't even figure out what to do on it. And Ebay was no help either. It didn't show any that looked like the one I have. I went to the "Mouser" site because I've ordered stuff off of it before when I repaired computers, but it to was so complicated as to asking questions I didn't even know how answer, I couldn't figure out what to write down. Lol. I know it's a one way valve that let's the current go in one direction and not in the other. The tech guy said, " Be careful to make sure you have it oriented as to the "cathode and the anode". ???? Huh? He said to put a volt meter on it and if there's continuity in one direction and not in the other put it in the direction that you have continuity, and that end goes down towards the starter. So that's what I did.

Long ago when I used to modify computer cases and repair motherboards and monitors I had it going for years. I've designed and built motherboard test stands and a bunch of stuff like that. It was fun. But it's been so long I've forgotten all of it. Electronics is something you need to keep up or you forget all the terminology and values and stuff. I have a large amount of left over computer and electronic stuff like resistors (many, many components like that type), and a ton of stuff like that in a bunch of those storage boxes with dividers, left over. Hint, hint, wink, wink I'd love to find someone to take all that stuff I have off my hands, cheap, really cheap. I've got whole computers, boxes of complete systems socket 775, hard drives, video cards that have fans on them, cpu's, optic drives. From heat sinks to different colored cat 5e cables, a couple of wifi modems, everything for doing tons of electronic projects. Some of it might be out dated but no electronics is ever really out of date. I've heard of old computers being used as slave units to run pumps for irrigation of fields and crap like that. None of it is completely useless.

 

[73c20jim]

That "valve" might be a diode????

 

[Ellie Niner]

@Raider L Sh¡t! It looks like I was talking Greek to myself, too... I just looked up the diode number, and I assumed correctly there, but a PNP is a transistor (as is NPN). What I should've said is "PN junction diode". I only know enough to poke through simple electronics and sometimes be able to roughly figure out how they function, but still am pretty green. Either way, your diode is installed so that power cannot flow back from the "R" terminal on your terminal block into that wire. Diodes usually have a stripe on the side opposite the direction power flows, so the stripe on yours would be facing up.

I'm at one of those points in life where I can't be taking in any additional stuff... Have had to downsize a couple of times in the last couple of years, and still have enough crap that it's spilling out into the carport and a workshop (that isn't mine).

 

[SquareRoot]

Boy, this thread has gone down a rabbit hole.

 

[Raider L]

@SquareRoot,

Boy, you ain't kiddin'. I'm getting loopy talking about the same thing over and over. I think it's past the point of being educational. It's still informative and fun though. And I would never resist talking about anything on these trucks. They will forever be interesting, even if the wires aren't always not like everyone's truck. GM engineer's were a strange group for sure. I think a lot of this wiring could have been more uniform in it's design, I guess. I'm not a engineer, I'm just a informed mechanic trying to figure out what the engineer's were trying to do, and trying to figure out what the heck they did something for. Like that #10 orange wire on the junction block that's supposed to be inside on the fan speed switch. But the schematic shows a #10 red wire on the junction block coming from the relay. The plug on my relay box doesn't even have a place for that #10 red wire. None of that makes any sense. Why did they do it that way? It's only caused a lot of controversy.

 

[Turbo4whl]

I'll take you further down the rabbit hole. When you have any kind of electrical coil, it makes a magnetic field. That magnetic field does the work to pull a pintle or close a switch.

When the coil power is shut off, the magnetic field collapses in on it's self. When this happens the coil generates a higher current voltage. Being a higher voltage it now flows backwards to the switch that just turned it off. The diode protects the switch or circuit.

If you look at the wiring diagram printed on a quality Bosch relay, along with the connections in the diagram there will be a diode.

 

[Raider L]

@Turbo4whl,

Yeah, isn't it a triangle shaped symbol? I've seen those, I think. So, what's the diode symbol? That's interesting about the coil voltage even though I know nothing about electronics enough to comment on what you said, that explains why the tech guy said to put the diode in that wire.