Painless 20120 Harness Installation

Discussion in 'Classic Mustang Specific Tech' started by geordie, Mar 24, 2008.

  1. so then just connect the two ampmeter wires together and hide them? I'm upgrading to a JME 6 gauge bezel and the voltmeter is replacing the ampmeter.
  2. Or you could use one of these tie points to connect them with eyelet terminals for a convenient point for any accessory relays that require battery power such as electric windows or door locks.

  3. so the ampmeter wires are a switched 12v source?
  4. No, it is full time battery voltage. One is tied to the output side of the alternator and the other makes its way back to the battery side of the solenoid.

    Typically relay circuits are fed battery voltage and then turned on to pass the high current through it. Low current input from a switch (which could be ignition or battery sourced) is what controls the relay. That is why I mentioned it would be a good point for relays.
  5. ok So not to hijack this thread but I am looking at the 3G alternator and the wiring diagrams that Painless has provided and have come to a sort of idea of how this works. I'm attaching the diagram with some sections highlighted.

    I think the yellow highlighted sections I can just leave out of the setup because they do not need to be used.

    The thing is I'm wondering where the red highlighted item goes if that is the case.
  6. See for the diagram I'm talking about. I am hoping to get some answers tonight cause I wanna finish the install tomorrow.

    I really think this painless harness is exactly what its name entails. Painless. Maybe I'm a bit more technically inclined though but I really don't think so. Well here's to hoping for help. Thanks guys.
  7. The red wire is the alternator (B+) output and will go to the battery side of the solenoid with a heavy gauge cable (I'm using a 4 ga). You might want to put a fuse in line with it. When the diodes in the alternator go bad they tend to short out and may cause some wire melting and possible fire.

    Of the yellow high lighted wires, you will still need the ignition switch wire white/black. If you do not have an alternator light put a resistor in there. (I'm using @ 560 ohm)

    This diagram helps.
  8. I used a 560ohm resistor and just have it hooked up to a 12v ignition source which I believe should be the same thing correct?

    So the fusebox has two wires going into the battery side of the solenoid? Seems odd but I'll go with it.
  9. ok I see what you're saying now about the B+ terminal. That diagram is good.

    My next question is where does that ignition switch wire go to now? I don't think it's the solenoid because there were already wires labeled I and S side of the solenoid. Hmm.

    If I can figure this sucker out I think I can fire my car up tomorrow for the first time in 5 years heh.
  10. Yes, you are not using an ammmeter, so a "loop" is not needed. Due to the higher output of the 3G, you will need a heavy gauge wire from the B+ of the Alternator directly to the Battery side of the Solenoid. You can eliminate some of the "congestion" at the solenoid B+ terminal by routing one of the fusebox feed wires directly to the alternator.

    Yes, The Green/Red wire is the "turn-on" signal from an ignition source through the charge warning lamp or resistor. You can route it to the 3G Alternator by using the White/black wire and tie it to the green/red wire at the voltage regulator that is not being used.

    The Yellow/White wire is the voltage sense wire. If you have the battery in the trunk, then you can run this wire to the battery and it will account for voltage drop and keep the level regulated to 14V.

    Here is a diagram that may help:

  11. Ok I've routed everything the way you say now I wanna check to make sure. In the diagram I had attached it was not setup to use an ignition box but I am using one. Now the box draws its power from the B+ side of the starter solenoid and it requires a 12volt switched ignition source to activate. My question is can I use the coil+ wire from the painless kit as my switched 12volt source?

    The painless kit has provisions for an ignition box but the instructions are for a duraspark II. I figure I can just bypass those wires and set it up per the MSD box instructions. My ignition is a duraspark dizzy with MSD 8152 box and a MSD Blaster 2 coil.

    I assume I can just tape off all the wires that say to connect "to ignition module" and just use the coil as a 12v source?

    I think that makes sense to me heh.

    I also have a few other questions for anyone that has done the painless install.

    1)my light switch has 1 empty space where no wire goes from what I can tell.

    2)my ignition switch also has 1 space where there is no wire

    3) does the cigarette lighter ground itself through mounting or do I need to ground it.

    4) if anyone has wired the painless harness to a 2 speed wiper motor I could really use some sort of diagram cuase it's very confusing as to what goes where.

    5) is it possible to run everything without hooking up the gauges for now? I am ordering a JME setup and It's just not here yet.

    That's more or less it for now. I wired the reverse lights and neutral safety switch to the T-5 but can't tell if it even worked yet.

    I'm figuring I should just keep asking questions in here so there's more or less just one big thread of Painless install stuff for us 65-6' guys.
  12. Just my opinion but I would never start a motor that has been siting for a while or hasn't been run/broken in without at least temp and oil pressure gauges.
  13. i have cheapo sunpro manual gauges installed right now until all my sensors come in etc for my autometer setup. I have the cheapo water temp and oil pressure with the crappy plastic tubing.
  14. 1) What Space? Here is a diagram.

    2) There should be 4 terminals connected, Battery power in, Ign out, acc out and start out.

    3) Yes it grounds itself

    4) Wiper diagram

    5) I would want to know the oil pressure if i was starting an engine for the first time or in a long time.
  15. the "A" Space had no wire going to it. Per the diagram provided by painless it was an empty space.
  16. That makes sense if there is a separate circuit feeding the brake switch.
  17. ok. So how does the rest of the setup look then? Am I alright using the coil wire as the switch to power the ignition box (which receives power from the battery) and just tape off the rest of the wires that are supposed to be used by a duraspark 2? or should I figure out how to wire it with those wires?
  18. I believe MSD says not to use the wire that feeds the coil as the hot for the box. I'm not sure if your new kit has resistor wire in it or not but if it has resistor wire in it, then don't use it.
  19. the wire does not have a resistor built into it. The directions call for the addition of it. Should I still find a different 12v wire or can I use the coil + wire?
  20. I'm installing the same harness in a 65 with some problems...

    It's the harness for a 1965 Mustang.
    I've run into a couple of things so far that have me wondering.
    The light switch circuit is giving me a problem. On page 22 of the instructions, the 'P' terminal on the switch goes to wire 926 to supply the front park lights.

    It works properly when I pull the light switch to the first detent to turn on all the corner lights.

    When I pull it out to the second detent to turn on the headlights, the front park/marker lights turn off when I'm thinking they should stay on.

    These are dual element bulbs so should have one on all the time and the second filament cycles on with the blinkers.

    I checked on the switch and sure enough continuity is cut between terminal B(battery) and P when pulled to the headlights on position (second detent)

    I bought a new switch to check if there was something wrong with my stock switch but it functions the same.

    So, what do I do to fix this problem?

    The second lighting problem is the dimmer switch wiring/plug. The wires seem to be terminated wrong into the dimmer plug.

    The power from the headlight switch is going to one side of the connector. with the low beam supply coming off of the other end and the high beam supply wires coming off the middle. This isn't correct for the way the switch works. When pushing the button, the switch makes continuity from the middle to one end and then swaps to providing continuity from the middle to the other end.

    So. The harness plug should be wired with power from the headlight switch going to the middle connector and the high and low beam supplies going one to either end of the harness plug.

    How do I fix this one?

    The last thing I have a question about are some unlabeled brown wires that have light blue insulated spade connectors on their ends in the dash harness. They come out after the ignition switch wires. I think they may have something to do with the heater blower wiring? Can't tell.

    So what are these?