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  #1  
Old 05-03-2022, 06:04 PM
gomowgto gomowgto is offline
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Default Holley sniper wiring problem

Trying to finish wiring my sniper unit on my 1967 GTO. The problem is finding a dedicated ignition source for the pink wire. The three top fuses in the fuse block show 12 volts when the key is in the run position, but when I crank the engine it drops to 1.5 volts. Holley tech said that's normal on these old cars and I need to wire in a 4 pin relay. I did that and it didn't help. I didn't change any of the wiring, and I labeled all wires going to the coil. The only thing on the coil I question is that I have both the red and a black wire with a white stripe connected to the + side of the coil. Both wires and the blue wire for the oil sending unit come from a small factory harness. I can't believe I labeled them wrong. I pulled the motor 6 months ago but I'm sure I labeled them correctly. Tomorrow I'm going to go over my grounds and clean and remove any paint as I did repaint the motor, but I've done this before and repainted and never had poblems.. I have both firewall straps connected to each head, negative cable connected to the block head stud, bare metal. Where did you all find a 12 volt source that would maintain 9-10 volts when cranking? Sorry for the long post. I think I covered everything, if I left something out, please ask. Please help. Thanks in advance

I will try to attach a pic of the coil wires
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  #2  
Old 05-03-2022, 08:03 PM
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Does the coil have voltage in the crank and run position? Original points, or something else? There are several ways this could be accomplished. But the coil wiring needs to be correct or you'll have issues even with the Sniper is getting power... Factory wiring manual should help you find where to get power in crank and run, and the correct voltage (source). You can trigger a relay with full battery voltage once you find the correct source.

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  #3  
Old 05-03-2022, 10:05 PM
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Will this help you?

Have Much, Much more ready!
Lifelong electronics tech. Will probably overload you.
Need email address.

Charles

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Old 05-03-2022, 10:35 PM
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So you can use coil + to trigger a relay to power the Sniper. Once you make sure the correct wires are going to the coil. Which should be easier now with this diagram.
ETA: you can also have the relay power an auxiliary fuse panel if you have more accessories besides the Sniper that need to be switched on in the crank and run scenarios.

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Last edited by Scott65; 05-03-2022 at 11:09 PM. Reason: Addition
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Old 05-03-2022, 10:41 PM
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Can email that and other stuff much better with email address.

  #6  
Old 05-04-2022, 07:20 AM
gomowgto gomowgto is offline
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I have the wiring diagram, but I can't see where the red wire comes from at all. What I see as a black wire with a yellow stripe, the diagram shows as a black with pink stripe. Both the wires match wires that come out of the top of the firewall connector by the horn relay, red on the right and black on the left. The diagram doesn't show any red wire going to the coil. With pertronix ignition the red wire from the distributor goes to the +, and black to - . Is there a way to trace these wires without unwrapping the harness?

Holley says do not source 12 volts from the coil.

Someone please chime in that has successfully installed this system on a 67 and how and where you found a 12 volt dedicated source that maintains 9-10 volts when cranking.

  #7  
Old 05-04-2022, 08:46 AM
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Probably being captain obvious but 1.5 v should still be enough to trigger the relay no? Then run your hot directly from battery through a fuse to the unit.
Admittedly not a 67 nor a sniper but I tapped the pink directly in my 71 fb and it works flawlessly. Is there maybe something wrong w starter/ battery or existing connections causing such a voltage drop?
I feel you pain, mixing old and modern can be a real test of wills.
Good luck!

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Old 05-04-2022, 08:52 AM
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I never suggested powering the Sniper from the coil. Power a relay from the coil. Not the same thing. IF you want the key to power the Sniper, you WILL be using those two wires, combined. There are numerous ways to do that depending on if you still have points or not. Good luck

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  #9  
Old 05-04-2022, 09:03 AM
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Ok, I re read the post, I don't have points.

  #10  
Old 05-04-2022, 09:12 AM
gomowgto gomowgto is offline
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Ifdstsve, you say you tapped your pink wire directly, are you saying you hooked it straight to the battery? They said I could do that and put it on a toggle switch, but I don't want to do that. I'm going out and check all my ground straps. I know I put multiple coats of primer, paint and clear coat on the motor plus new motor mounts and I just bolted the ground straps to the block without removing the paint from those areas. They always say poor grounds can cause all kinds of problems.

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Old 05-04-2022, 09:43 AM
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You can use a multimeter to check continuity between the wires at the coil, and and the two positions coming out of the bulkhead connector that are shown in the wiring diagram to verify the correct 2 wires are going to the coil. You can then check voltage to each of them to verify if the resistor wire is still doing its job. Here's what I did on my 65 which had two wires to the coil like yours. CAVEAT: I don't care about perfect originality. And, I had already replaced the resistor wire at the bulkhead for full 12v.
I cut the two wires at a convenient location to wire them together in a ring terminal, connected to a junction block on the firewall. Now I have a permanent place to trigger relays etc for anything requiring key switched, crank/run power. I ONLY use it to trigger relays so as not to overtax the original circuits. If I can find a picture I'll post it.
ETA: you could power a 4 position fuse panel this way via a 40 amp relay, (with appropriate gauge wiring) and then feed the coil from one, the Sniper from one, and have a couple spares. As long as your ignition no longer requires the resistor wire.

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Last edited by Scott65; 05-04-2022 at 09:46 AM. Reason: Addition
  #12  
Old 05-04-2022, 09:52 AM
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This is a 2 pole junction available (obviously) from Jegs. I use one side(the larger terminal) for full 12 volt battery (always hot), the other (smaller) terminal is for the previously mention circuit for key on crank/run power.
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  #13  
Old 05-04-2022, 10:05 AM
gomowgto gomowgto is offline
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I sure wish you lived in Michigan, I'd pay you to come do this. You're talking to a novice when it comes to electrical. I would have to get a probe connector for my multimeter. I had this car to the same shop last summer that did my motor work this winter. They did in fact remove the resistor because they said it was only supplying 9 volts to the coil and pertronix requires 12 volts. I have an appointment to get this car in to them but not til the 26th of May. If I can't figure this out before then. I've always felt that if you don't know what you're doing, leave it to those that do. I'd rather pay and have it done right. I already spent money on a relay that is now non returnable and I don't want to keep throwing money at what I'm not sure is the actual problem. Your way obviously works but if I don't get it right, then I end up further behind the eight ball. I don't have a lot of confidence in my electrical skills.

  #14  
Old 05-04-2022, 10:23 AM
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I understand. If you can verify that (at the coil) you have one wire with 12v in crank, and another with 12v in run, we can easily walk you through using the relay to power the Sniper wire.

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  #15  
Old 05-04-2022, 10:33 AM
gomowgto gomowgto is offline
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Ok thanks. I really appreciate it. I will check it and let you know.

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Old 05-04-2022, 11:05 AM
gomowgto gomowgto is offline
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Ok. Red wire and black w/ yellow stripe disconnected from + coil post.
Rewire
Key off. 0 volts
Key run, 12.32 volts
Cranking, 0.56 volts

Black w/yellow stripe

Key off 0 volts
Key run, 0 volts
Cranking 8.9-9.16 volts.

I did not remove my engine ground straps to remove paint, but I connected a jumper to all the grounding points with the multimeter and they all showed the same as the battery, 12.62 volts. Is there any other test or should I just clean them anyway?

  #17  
Old 05-04-2022, 11:09 AM
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I also have the positive wire to the sniper unit connected to the + battery terminal, but no - connected. That's what the video said to do. + only.

  #18  
Old 05-04-2022, 11:19 AM
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You can check resistance between the ends of the ground straps. Or just clean them really well and be done. From your checks it seems you could easily use the coil + to trigger your relay. Is it a conventional 4 lug relay? If so, find a place that's most convenient to locate the relay, then wire it as such:
12 volt fused power to terminal 30
Sniper (pink) wire to terminal 87
Wire from coil+ (added by you, leave the originals connected at the coil) to terminal 86
Good ground wire to terminal 85
Hopefully the Sniper directions tell you the expected load on that wire, size the fuse accordingly.
The 12v power is pretty much at your discretion for where you get it from. A small load could probably be powered simply from an unused fuse block spade terminal, or with an inline fuse, straight from battery(probably better due to cutting out potential alternator noise).

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Last edited by Scott65; 05-04-2022 at 11:31 AM. Reason: Addition
  #19  
Old 05-04-2022, 11:22 AM
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The main power and ground are likely recommend to be connected directly to the battery. I've never seen Sniper instructions, but all others I've seen are pretty adamant about that.

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  #20  
Old 05-04-2022, 11:42 AM
gomowgto gomowgto is offline
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Yes, the actual sniper wiring harness' + and - go directly to the battery, but before looking for the dedicated ignition source, the video shows to connect the + cable to the battery but not the -. I have that actual rely you are talking about and I had it wired in at the fuse block, but none of the 3 dedicated ignition fuses had enough voltage when cranking to keep the relay active. It needs 3 volts to stay active, I only had 1.5 volts.
I will just clean the ends but I will take a before and after resistance test to see if it improves.
I'm assuming that I do in fact have the 2 cool wires connected correctly by having them on the + side of the coil. That is how I had them marked. When it comes to connecting to the coil +, do I just connect at the + coil post or up in the wire somewhere, and to the red or the black, or doesn't it matter?

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