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Thread: Wiring with MSD 6 series box and Painless Harness.

  1. #1

    Default Wiring with MSD 6 series box and Painless Harness.

    I'm getting ready to install the 1250 Sniper Kit on my '69 Camaro. I rewired the car previously with a complete Painless Harness. To make sure I have this correct.

    It's clearly stated the Sniper needs a clean 12V switched source with power at crank and run (pink wire). My MSD box currently uses a switched 12V wire (smaller red wire on the box). Both of these will now need separate switched 12V sources?

    Painless mentions in their manual that some aftermarket EFI systems power the coil (or box in this case) THROUGH the EFI harness, therefore in that case the coil+ wire in the harness can be used to switch the EFI. It looks like this is NOT the case with the Sniper and the MSD box and Sniper require separate 12V switched sources? (Same question as above.)

    If they need separate 12V sources, I can use the coil+ wire from the harness for one. The Painless Harness also has a dedicated electric fuel pump wire, which I currently have powering my pump. I see the Sniper also has a fuel pump power wire. Would this be the best solution: use the coil+ wire to power the MSD box, fuel pump wire from Painless (car) harness to power the Sniper, and power my fuel pump with the fuel pump wire from the SNIPER harness? Thank you very much in advance for any help.

  2. #2
    Join Date
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    Since you don't need the old fuel pump wire, I'd use that. Does the diagram from the Painless Harness show it going straight to the fuse box?

  3. #3

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    Yes, I believe it does come straight from the fuse block. The Sniper & MSD will both need their own 12V switched wire?

  4. #4
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    They do not need there own individual source. They can all be tied to one clean spot such as the ignition switch or relay with some sort of junction. If your really picky, you can use two relays one for the ECU and then tie the CD box and distributor to there own relay or junction stud. Personally, I wouldn't use the actual ignition coil for anything. It probably would work if the coil positive is in the fuse box and not the actual ignition coil and works in the crank & run position. Although you could try it and then check to see if you get EMI. For the MSD box, why not use the starter or battery?

  5. #5

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    The heavy red wire from the MSD box does go straight to the starter and I plan on keeping it there. Does everyone usually use the fuel pump wire from the Sniper to power the fuel pump? Seems more logical than not using it. Thanks.

  6. #6
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    Yes, because it primes the pump once the ECU gets powered.

  7. #7
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    Yes, that's the Fuel Pump Prime Time, then the ECU runs the fuel pump again when it reads an RPM signal.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  8. #8

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    Sounds like that's fairly straightforward. The other thing I wanted to check is that Holley says only four connections needed (Battery +, Battery -, Switched Ignition & RPM). Battery is simple enough, we talked about the switched 12V. The RPM they refer to is the engine speed input? Which would be the yellow coil wire or, in my case, the yellow coil wire isn't used? Engine speed is read by the violet crank signal + in the dark green/violet connection to the distributor?

  9. #9
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    Use the purple adapter wire and plug it into the tach terminal on the MSD box and the green & purple twisted connector from the 7-pin harness. It sounds like you're not going to be controlling timing with the Sniper?
    Last edited by Leon82; 07-17-2019 at 11:04 AM.

  10. #10
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    Quote Originally Posted by jfj85 View Post
    MSD Pro Billet distributor...
    https://forums.holley.com/showthread...511#post217511 (Related Forum Post)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

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