Be careful tapping for power on things like the ecm and MSD, they like a clean power source.
CK5
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Black Betty - Formerly Blaze the Monster Machine
- Thread starter centexk5
- Start date
1984 K5 Project for Dad and kids
I believe that he is just connecting the relay coil trigger wires together, then running through the relays for power to each.
Sounds good to me, but I'm no expert.
Correct. All battery 12’s are direct to battery.
Wow. I over think things sometimes. Why am I triggering a relay for a wire that’s triggering a relay in the ecm? I mean, I could do it that way, but why.
1 - No, in fact I purposely hook it to a wire not hot while cranking, to avoid the potential feedback/run-on issue from having them on the same circuit.
2 - Using that wire to turn both on is fine, like you stated above, they are just low current turn on wires, no relay needed.
Please note, I purposely do not hook anything else directly to the battery, only the ECU. Not the fans, not the CDI box, nothing else. This ensures the battery is the cleanest source possible. I hook other stuff to a junction block and/or the starter, to the frame a couple feet from the battery for ground, etc. If we hook everything directly to the battery, all it does is add noise and create a more dirty power source that is impossible to avoid. Keeping the interference away from the battery helps this. Now, the CDI box and other stuff still needs a solid power and ground with proper size wires, it just doesn't need to be connected directly to the battery.
I also mount the CDI box at least a couple feet away or more from the ECU, and I don't run any ignition wires parallel to any ECU or sensor wires, especially the wires to or from the coil. High voltage can create a lot of noise, and low voltage is very susceptible.
Noted on the CDI to battery cause that was my plan. The rest were going to be on a junction block.
CDI is mounted on the passenger fender well. ECU is going in the glovebox. There’s a giant AC//heater unit in between (that is highly aggravating to work around).
Didn’t think the wires to the coil would be high enough voltage to cause any disruption. Now you got me rethinking my wiring pathways.
CDI is mounted on the passenger fender well. ECU is going in the glovebox. There’s a giant AC//heater unit in between (that is highly aggravating to work around).
Didn’t think the wires to the coil would be high enough voltage to cause any disruption. Now you got me rethinking my wiring pathways.
Ok. Took a second look. Reran the main power cables for the ECU so they are completely isolated from anything. Previously the were going same direction as coil wires. CDI box I’m going to grab power from the starter. Coil wires are about 6-7” away from the main harness but runs perpendicular.
Only point I’m pondering is I’ve got the harness going through the firewall directly behind the distributor but it’s a fairly short amount of exposure and all the plug wires would be going perpendicular to it and those are shielded.
Now I’ve gotta figure out how to run the remaining smaller battery wires and switched wires. I’m now way over thinking this and am freezing up on it.
Remind me why I didn’t go carb?
Only point I’m pondering is I’ve got the harness going through the firewall directly behind the distributor but it’s a fairly short amount of exposure and all the plug wires would be going perpendicular to it and those are shielded.
Now I’ve gotta figure out how to run the remaining smaller battery wires and switched wires. I’m now way over thinking this and am freezing up on it.
Remind me why I didn’t go carb?
I’ve spent as much time as I’m going to on this.
CDI box is now routed to starter for battery power and will ground direct to frame.
Coil wire goes over the top of the AC box and over.
Main power harness for the ECU goes inside the fender, down the firewall, and through a hole under the blower motor.
12v battery for transmission harness, a separate 12v for the main harness, and the 12v fuel pump wire go through the firewall, along the bottom of the fender well, and the 2 harness wires will tie into a distribution block while the fuel pump wire will be used to trigger a relay that will run the fuel pump itself. The 12v trigger wire for the cdi box runs this same path the opposite direction.
The only wire I have left to run, is the points wire from the ECU harness to the CDI box. How critical is that to be isolated from everything? Because frankly my give a damn is to the point of wrapping wires in aluminum foil so I can be done with this.
CDI box is now routed to starter for battery power and will ground direct to frame.
Coil wire goes over the top of the AC box and over.
Main power harness for the ECU goes inside the fender, down the firewall, and through a hole under the blower motor.
12v battery for transmission harness, a separate 12v for the main harness, and the 12v fuel pump wire go through the firewall, along the bottom of the fender well, and the 2 harness wires will tie into a distribution block while the fuel pump wire will be used to trigger a relay that will run the fuel pump itself. The 12v trigger wire for the cdi box runs this same path the opposite direction.
The only wire I have left to run, is the points wire from the ECU harness to the CDI box. How critical is that to be isolated from everything? Because frankly my give a damn is to the point of wrapping wires in aluminum foil so I can be done with this.
Ran my battery to starter wire and one of my frame grounds. Need to go pick up a couple of bolts to tie the engine to frame ground. Going to use the empty bolt hole where the fuel pump would normally go. Vortec block doesn’t have the opening for a fuel pump but it’s got one bolt hole that’s threaded. 
You are getting close, just keep at it and you'll be rewarded.
Make sure you protect and also prevent that main starter cable from rubbing on the frame or block.
Make sure you protect and also prevent that main starter cable from rubbing on the frame or block.
Oh come on. Direct shorts are always fun.
I'm just loosely running stuff at the moment. Trying to find my pathways. Need to buy some more cable and lugs.
I'm just loosely running stuff at the moment. Trying to find my pathways. Need to buy some more cable and lugs.
I see your fan shroud looks like the new one I put on a truck I used to have. It was too short for the fan. I was always told the fan blades should be halfway into the shroud to get proper air flow. I extended mine with some copper sheeting I had from work but sheet metal works good too. I just made a circle and riveted it to the shroud to get the proper depth engagement for the fan blades.
It's left over from my previous blazer. Not ideal but it'll get me going.
I figured. Just giving you a heads up before it gets hot out. Mine was a brand new one but they suck for quality if you can find them at all.
I would like to see how it fastened to radiator and brackets. I have never seen one that far off. I had the opposite problem to deep into shroud
Last blazer had a big block radiator in it and so I've got the big block radiator upper mount on this one. But I've only got a regular small block radiator in it. I went to go put the small block radiator mounts on it this weekend and found out the top bolt holes on the fan shroud are off about 1/2". So it sits until I get the energy up to order a different fan shroud or just build one myself.
put the big block radiator back, cause ... you know ... global warming 
No seriously the Big block rad will work just fine with a small block
No seriously the Big block rad will work just fine with a small blockYes but it was trashed and I already have this one.
Started wiring some things up. Relay for the fuel pump. Distribution block for batt power. Got another block for grounds that I haven’t done yet. 
Bear with me while I try to explain this. I'm trying to un CF the rats nest of a factory harness so I can get electrons flowing where they need to be. All of these wires are in the same trunk as the wires going to the starter. I've found the wires for the solenoid and battery but I think I've got a mix of other wires in here. Are my notes on these accurate? I've got 3 wires that I have no clue where they go.
