Switched Ignition Source

[Elliott Taylor]

Hey Guys,

I'm almost done installing my sniper EFI on my 77 Camaro. I'm trying to find a switched 12 volt source from the factory harness to tie into the pink wire on the sniper harness. It has to be on in the "on" and "cranking" positions. I tried to use the wire the previous owner had designated for the electric choke, but it doesn't have voltage during cranking(it does in the "on" position). I tried the batt tab on the fuse panel under the dash, but it obviously has power even without the switch on. There is a small green wire under the engine bay that does meet the criteria, but I can' find where it terminates. I don't have anymore unused terminals on the fuse panel.

Any ideas? Have you guys hooked up a Sniper on a 2nd gen?

Thanks

 

[CorkyE]

I don't know the amp draw on your Sniper, but I used the HEI ignition power wire for my ProFlo 4. You may be able to splice into that wire. Also check Holley's web site for the Sniper, I'm sure someone else has ran into this with a 2nd gen. There also are threads here where members have installed Sniper systems, a search might turn up something.

 

[Jim Streib]

Hey Guys,

I'm almost done installing my sniper EFI on my 77 Camaro. I'm trying to find a switched 12 volt source from the factory harness to tie into the pink wire on the sniper harness. It has to be on in the "on" and "cranking" positions. I tried to use the wire the previous owner had designated for the electric choke, but it doesn't have voltage during cranking(it does in the "on" position). I tried the batt tab on the fuse panel under the dash, but it obviously has power even without the switch on. There is a small green wire under the engine bay that does meet the criteria, but I can' find where it terminates. I don't have anymore unused terminals on the fuse panel.

Any ideas? Have you guys hooked up a Sniper on a 2nd gen?

Thanks

In your fuse block close to the center you should have an output labeled IGN. There may be something plugged into it but this output should show voltage when the key is in the RUN and CRANK position and dead in all other key positions.

If this wire for the EFI is just a trigger wire, then it will not be pulling hardly any amperage and one could use the IGN output on the fuse block but if it is pulling something like 10A then another solution will have to be found using a relay and some other parts.

If you are able to use the IGN output on the fuse block and there already is something in there, you can make up a "Y" plug to where when you unplug the connector that is in there, the fuse block will have a 1/4" male terminal and the thing you unplugeed will have a 1/4" female terminal. By making up an adaptor with a male and female connector on a new wire, you can set this up to have things plug together or to be taken apart later if needed real easy. The factory designed add on options to be this way so a mechanic did not have to cut into or splice into a wire. They wanted more of a plug and play setup.

This is a fuse block in my 74 and it has something plugged into the fuse block but then a male dangling end for adding another item.

Jim

 

[Elliott Taylor]

Ok, thanks for the replies. The terminal labels IGN is already taken, but actually Holley recommended I run a 4 pin relay to the ignition switch to make sure l have enough voltage when cranking. I'll attach a picture..it would need to run to the battery, have a chassis ground, have the 12v switched source running from my efi harness to the relay, but what about the 12v ? He says run it to the ign switch, but how exactly would l do that? Thanks

 

[Jim Streib]

If they are so worried about not getting enough voltage to the ignition wire of their setup, then the relay might or could solve issues BUT will really need to have it's main power into the relay from the battery positive post (and it's a shame too that in the link you posted with the relay it is not showing any fuse protection information on things which can make things very unsafe).

The relay will still need to be activated by a circuit already on the car and like I said, even though you have something plugged into the IGN spot on the fuse block, doing an adaptor properly will work fine. Basically this adaptor would be like you wanting to add something electrically into your house on a double outlet but the outlet is full. One just has to get the proper extension cord to split the outlets into many more sorta like adding in a plug strip to have one outlet power a light, a power pack for a computer, a stereo receiver, a DVD player, a sound bar, and so on. As long as things are not overloaded, you are fine.

Jim

 

[Elliott Taylor]

In response to your first reply, could I just use a standard spade connector with 2 wires similar to the blue connector in your 2nd picture ?

 

[Jim Streib]

In response to your first reply, could I just use a standard spade connector with 2 wires similar to the blue connector in your 2nd picture ?

You can cut the terminal off of the wire plugged into your fuse blocks IGN terminal and then strip the end of that old wire and then also on the new wire you want to add, then twist the bare wire ends together, and then crimp on a new 1/4" female onto both of the wires. Then plug this new terminal with two wires off of it into the IGN male terminal in the fuse block.

Jim

 

[Elliott Taylor]

Ok thats what I'll do. Not sure why they recommended a relay, but I'm glad l asked you first. HOLLEY also said make sure the wire already going to the IGN terminal is "clean" and is only powering the ignition switch. Does that make sense ?

 

[Jim Streib]

Ok thats what I'll do. Not sure why they recommended a relay, but I'm glad l asked you first. HOLLEY also said make sure the wire already going to the IGN terminal is "clean" and is only powering the ignition switch. Does that make sense ?

You have to remember that when they are designing things, not always are the systems going to be put on pristine cars but could be going on cars with fresh brand new harness with minimal voltage drops or they could be put onto cars that the wiring harness is so shot and poor that there is excessive voltage drops to things. Case in point look at guys adding headlight relays. A lot of times it does work on older cars but not in all cases and if there is a difference, it might be so small you never see it.

IF for some reason the IGN terminal is dropping too far down on voltage, then the relay could be the answer but to confirm this one would need to take measurements at the IGN terminal and then at the battery to see how much difference there is.

I also have to think these systems have a working voltage window in that they should work with voltages between let's say 10V and 15V. Going above or below this might not have the system working like it should.

Just keep in mind that the IGN terminal (as well as the ACC, BAT, and LPS terminals) in the fuse block are protected by a neighboring fuse and one could add too many things to the "tap" as I call it and if it does become overloaded one just cannot pop in a larger fuse as the supply side of things is only so big.

Jim

 

[BonzoHansen]

you need an underhood or underdash source?