Continuous 12V power signal while cranking for Holley Sniper EFI

[scottie43]

Just completed updating my 71 Cuda 383, 4speed to Sniper EFI. I need a continuous 12Vpower source when the ignition is turned on and is not interrupted while cranking the engine. I've found a couple sources, such as the ACC blank on the fuse panel and also the yellow 3 port power source under the dash but both of these interrupt when cranking the engie. The ECU needs continuous 12V power even when cranking the engine. Anyone install one of these systems or can someone tell me where I can find uninterrupted 12V power source activated by the ignition switch?

 

[rklein71]

I soldered a wire between the two back side leads on my ballast resistor so that I get 12 volts to the Sniper unit both in start and in run. It worked for me.

 

[romi]

Yes, the balast resistor is the best spot.

 

[scottie43]

Thanks for the info. I'm still a bit confused. Where is the balast resistor located? I believe I found mine on the firewall but looks like it already has some sort of wire on the back side. Where do you connect the pink wire? Sorry if I sound dumb...this is my first Mopar!

 

[rklein71]

Thanks for the info. I'm still a bit confused. Where is the balast resistor located? I believe I found mine on the firewall but looks like it already has some sort of wire on the back side. Where do you connect the pink wire? Sorry if I sound dumb...this is my first Mopar!

You remove the existing wire in the back of the ballast as that is the resistor that limits voltage to the coil during run conditions. Solder the new wire in its place. I used epoxy to fill over the solder connection, probably not necessary.

 

[scottie43]

Do you reconnect the wires that belong on it? Can this damage the coil if the voltage is not regulated? And I'd assume it makes no difference which side you tap in the pink wire to? This one has thrown me for a bit of a loop! I had no issued putting the entire system in until this pink wire! Car actually started with the pink wire connected to the "ACC" spot on the fuse panel, but then only stars occasionally. Alot of online reading explained what I needed to do!

 

[rklein71]

The brown wire to the ballast resister is 12 volts in the start position. The dark blue wire is 12 volts available in the run position which goes thru the ballast resister. A second brown wire goes to the positive side of the coil in a stock application. Since you have bypassed the resister in the ballast, you will get full 12 volts to the brown wire to the coil in both the start and run positions. You want to connect the pink wire to the brown wire that originally went to the coil. Now you have 12 volts to the ECU in the Sniper unit. A yellow wire from the Sniper harness goes to the negative side of the coil according to the Sniper manual. That is the coil signal.

 

[rklein71]

 

[scottie43]

I've spend hours reading on this and still am confused. I have my original distributor, coil and points and wanted to keep that in use. Is this possible with what you are describing here?

 

[rklein71]

When I first installed the Sniper, I was using an HEI. I later upgraded to the Hyperspark ignition system. You might need to contact Holley to ask about using points.

 

[scottie43]

That's what I thought. Seems like a simple but expensive fix if I upgrade to Hyperspark. Thanks for all your help....

 

[MoparCarGuy]

Carefully reread the Sniper manual's section on wiring. You need a "clean" source of Switched 12V to the Pink wire. The manual states, "Don’t connect the PINK switched +12V wire to “dirty” sources, such as the ignition coil, audio systems, or 12V sources connected to HID head lamps."
The ballast resistor is connected to your ignition coil so it is a NO-GO for the Pink wire. That connection would be too close to ignition components and EFI kits are very susceptible to electromagnetic interference from the ignition. Find a switched source inside the car at the the fuseblock. Use a multimeter to verify you have 12V in both the Start and Run positions.
Watch this Holley video: Connecting the Pink Wire to Switched 12V Source

 

[MoparCarGuy]

Separately, the best ignition for the Sniper or Terminator X EFI kits is definitely the HyperSpark ignition, coil, and distributor. Full timing control by your EFI kit from the driver's seat.

 

[DaveBob]

Just completed updating my 71 Cuda 383, 4speed to Sniper EFI. I need a continuous 12Vpower source when the ignition is turned on and is not interrupted while cranking the engine. I've found a couple sources, such as the ACC blank on the fuse panel and also the yellow 3 port power source under the dash but both of these interrupt when cranking the engie. The ECU needs continuous 12V power even when cranking the engine. Anyone install one of these systems or can someone tell me where I can find uninterrupted 12V power source activated by the ignition switch?

Scottie43 - Shorting out / disabling the ballast resistor may work, depending on coil selection, but is not required for what you are doing. Using any number of circuits that are at 12v during run to operate a relay between the battery and the EFI would have been my first choice. Check the schematic in the factory manual for your choices to operate the relay. This also assures that you obtain a "clean" power source for your EFI. That said, the ballast resistor is there for a reason. When cranking an engine to start it, the current spike causes a voltage drop. (Power = current x voltage.) During this time, the normal system voltage will no longer be 12v, but something much less – say, 9v, for example. If the coil was powered through the ballast resistor during start, the additional voltage drop across the ballast resistor will reduce coil voltage even further (down to 6v, for example) and your engine may not start. That is why the ballast resistor is bypassed during start, so the coil gets the voltage it needs (9v in this example) to operate properly. Once the engine is running, the supply voltage for the coil runs through the ballast resistor which reduces the 12v to the voltage the coil needs to operate properly. For a stock coil, that optimal voltage is less than 12v by the amount of the voltage drop across the ballast resistor. Bypassing the ballast resistor to provide a constant 12v to the coil will not damage the coil, but only if the coil is designed to operate on that voltage or has an internal resistor that duplicates the voltage drop of the ballast resistor.

 

[rklein71]

If you are using HEI or the Hyperspark ignition, the ballast resistor isn’t needed. With the hyperspark, the stock brown wire is not even used.