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Technical Now I have a short.

Discussion in 'The Hokey Ass Message Board' started by K13, Jul 28, 2020.

  1. Sorry I was getting the info of what I have (unfortunately the above diagram doesn't correspond to what I have so I don't know what changes need to be made.) I have 4 wires at the ignition switch. SW power (BATT terminal), SW Acc (ACC Terminal), SW Coil, SW acc (IGN Terminal). I have a three wire alternator and the aforementioned single pole starter. Not sure if there is any other infomation that I need to provide?

    I removed all the wires from the ignition switch other than SW power with ignition wire back on the other end and I am still getting a draw from somewhere.
  2. Your alternator could have an internal drain. Try disconnecting the small exciter wire, then the field wire, and finally the large charge wire. See if that finds the problem. Your exciter wire is ignition on, but the other two are constant battery hot.
  3. Seems to be the problem. Brand new alternator but when I disconnect the field wire light goes out plug it back in light goes on. That would also explain why I wasn't getting the draw before. I couldn't get the truck to shut off so I replaced the alternator. Fixed that problem and created another. Starting to piss me off. Oh and I did have everything wired correctly I spent a fair amount of time on the phone with Rebel Wire yesterday trouble shooting. I can't speak highly enough about their customer service.
    Last edited: Jul 30, 2020
    pprather and Blue One like this.
  4. Blue One
    Joined: Feb 6, 2010
    Posts: 10,590

    Blue One
    from Alberta

    You seem to have an electrical gremlin living in your garage.
    Troublesome little bastards, I hope you can trap him or scare him off. :D

    I can understand your frustrations, I’ve had my share of that too.

    Hope you can get it worked out.
    BigDogSS likes this.
  5. Thanks Larry. The most frustrating part is I have torn apart half my truck trying to find a problem to end up replacing a supposedly brand new piece.
  6. Blue One
    Joined: Feb 6, 2010
    Posts: 10,590

    Blue One
    from Alberta

    I understand completely.

    I still haven’t got back to sorting out my issue since I was over to your place, I’m still building my monster new storage shed.

    I wanted to be out cruising around but with all the rain we had up to now it didn’t go well with the RPU or with trying to build outdoors.

    The end is in sight for the shed and maybe the rest of the summer will be better.

    I hope you can get things sorted out, it would be nice for you to be able to get out for some road time too.
  7. It would be nice. I was done. Getting ready to take it for a short spin before I booked an appointment for my out of province when I went out to start it and the battery was dead and then all this bull shit. :mad:
    Blue One likes this.
  8. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,834


    On older cars, starter circuits, cigarette lighters, and even headlight circuits are unfused.

    I'd think a dead short would have melted a wire by now.
  9. The exciter wire should be connected to the ACC terminal at the ignition switch, not ignition or unswitched power. That will prevent 'backfeed' that keeps the motor running after turning the ignition switch 'off'.

    This connection is why on cars with idiot lights, the light would come on when you switched to ACC to listen to the radio without running the motor.
    Happydaze likes this.
  10. Mannnnn,,,
    Two days ago you unplug the alternator and you get the same result the light stayed on?

    The coolest thing about electricity is the electrons always follow the rules and do what they’re told to do. Always. When electricity isn’t doing what you want to do it’s because something is giving electrons different orders.
    firstinsteele likes this.
  11. Happydaze
    Joined: Aug 21, 2009
    Posts: 947


    Thankyou thankyou thankyou! :)

    That gives me something to work with on a problem I have on a partially wired new build project. I was thinking the run on was engine timing related, but wasn't sure. My installation is more complicated as I have a grounded, one wire light, as the idiot light, so have used a relay. I've been suspecting issues with the relay too and now have one with a diode in it, but not installed yet. Project is on a bit of a back burner right now. Must get back into it as soon as possible.

    But thanks again!


  12. Well something is seriously fucked. I seem to have fried another alternator. I literally have nothing hooked up but the main power on the switch, battery, alternator and main power feed from the panel. Replaced the alternator seemed to be fine. Started putting things back together checked again (thinking what 31Vicky had mentioned) light back on, pull the field from the alternator light off. I haven't even hooked up the negative terminal on the battery. WTF!!!
  13. If you have NOTHING connected to the negative battery terminal, that light shouldn't light up. The only possibility I can think of would be if you have a battery hold-down, it's somehow semi-grounding the battery. Look the battery over really well...
  14. The light is between the negative battery lead and the negative battery terminal. It was fine when I first installed the alternator no light then 10 minutes later it lit it up again. How would that miniscule draw blow the alternator? Oh and I don't have a tie down on the battery at the moment.
    Last edited: Jul 30, 2020
  15. MAD MIKE
    Joined: Aug 1, 2009
    Posts: 543

    from 94577

    Need to start posting some pictures.
  16. Atwater Mike
    Joined: May 31, 2002
    Posts: 10,180

    Atwater Mike

    ??? Lift the battery from its metal base, place a board underneath it.

    Methinks there's a hole or piece of metal shaving under the adjoining cell that's making 'loose contact' internally with battery negative- side. This is a strange one.
  17. Ok, weird attack over.

    You said you installed a three-wire alternator which should have a integral regulator. Read this:
    and make sure wires 1 and 2 are connected as shown and aren't swapped or connected in the wrong place. The 'sense' wire should be connected before the ignition switch, preferably at the fuse panel or close to it. The idiot light wire (whether you use a light of not) should be connected to the ACC terminal on the ignition switch. Very few of the diagrams for these that I see make this clear. DO NOT connect it to the ignition/run terminal, that's where you get the issue of the motor running after turning off the key.
  18. Not much I can easily get picture of. I have the labelled main fuse panel power wire, + terminal battery wire, starter wire and main alternator wire hooked together via a bus bar because the terminal on the starter is too short. I have the exciter wire, main power and jumper on the alternator. The jumper wire is just a short wire from spade terminal to the main power feed. Exciter wire goes straight to fuse panel on the designated exciter wire. I have one wire coming off the BAT terminal on the ignition switch that is the dedicated IGN power wire. That is it. I have ground at the alternator. Main battery ground goes to engine block then chassis and body.
    Last edited: Jul 30, 2020
  19. Alternator is hooked up with the main power wire on the back. The exciter wire to the #1 terminal and the jumper from the #2 terminal to the main power wire. The battery is sitting on rubber in the battery tray. The run issue was solved by the original new alternator so I thought it was an internal alternator issue originally.
    Last edited: Jul 30, 2020
  20. The exciter wire should be connected to the ACC terminal on your ignition switch, not unswitched power. This is your power drain.

    The 'jumper' should be connected not at the alternator output but to the fuse panel. This is your 'sense' wire, where it's connected now makes operate just like a one-wire alternator.
  21. It is there is no power to it when the ignition is off. I only get power to it with the acc wire connected to the switch and the switch turned to acc.
    This is how I have it wired unless something is not right in the fuse panel. Sorry just noticed this has the exciter going to ignition I have it going to ACC.
    Last edited: Jul 30, 2020
  22. But that's NOT how you have it wired by your own admission. The jumper from terminal 2 is the wire that's supposed to go to the fuse panel, not to the alternator output. The other wire shouldn't go anywhere near the fuse panel, and if there's a wire identified as 'exciter' coming out of the panel it's wrong. That would be a 'sense' wire, and it's supposed to be connected to a unswitched 12V source.

    If you're using a wire from the fuse panel to connect to the ACC terminal, it's probably not doing anything. The only way that would work is if the 'exciter' wire passes through the fuse panel with no connection. If lifting that wire at the alternator clears the light, there IS a connection in the fuse panel

    For clarity, I'll explain how it's supposed to actually work. The battery output is just that; it goes to the battery and supplies the power needed to run the car as well as keep the battery charged.

    The sense wire is how the regulator determines output. It's looking for around 14.1 or so volts, as load changes it adjusts output to maintain that. Now here's the important part: It senses voltage at the point of connection. Why is this important? Because both the OEMs and aftermarket harness suppliers never use wire between the alternator output/battery and battery/fuse panel that's actually big enough for all actual loads. So have a big load, and you get voltage drop in one or both of those wires. So if you have a one-wire alternator or jumper directly to the output as you have, you could see a voltage drop of up to 15% at the fuse panel, possibly more because the regulator doesn't 'see' this drop. With the sense wire connected at the fuse panel, the regulator will boost voltage output to compensate, restoring full voltage at the panel. Some of you guys using one-wire alternators or jumpering a three-wire like this and complaining about dim lights or installing relays, this is one of the contributing causes.

    The exciter wire has a limited purpose. It's only purpose is to supply the initial 12V to start the alternator charging. But once the alternator does start charging, this terminal starts outputting 12V. If you have a idiot light installed in the wire, it goes out as there's no longer any difference of potential; it's getting 12V+ from both directions. This is also why this wire can't be connected to the ignition circuit, but has to be switched separately.

    Both the sense and exciter wires have very, very low current flow in them, the exciter will go to near-zero once charging occurs. Neither needs to be fused, but if you're a real paranoid, a 3 amp fuse in-line is plenty.

    I'll also note that those 'chip' regulators probably don't like being energized for long periods if no idiot light is installed. The light acts as a current-limiter, you may be overheating the regulator without the light. In normal use it won't matter.
  23. The exciter wire runs through the fuse box. I have no idea what it does inside the fuse box but it has zero voltage unless the Acc wire is hooked to the switch and the switch is turned to the Acc or on position. It's hard to see but it may run through a 4 amp fuse as there is one on the fuse panel in about the area it looks like the exciter wire goes to(edit: I don't think this fuse has anything to do with the exciter wire.) I originally had the second wire on the top of the alternator running back to the bus bar (10G I believe)but every diagram I have seen online showed it jumped straight to the the main feedline so I made the little jumper. It has never gone to the fuse panel. Perhaps my explanation was not clear.
    Last edited: Jul 30, 2020
  24. The white wire is labelled excite and runs to the fuse panel. It has no power unless the switch is turned on. The red wire (on top) runs back to the main bus so unkeyed power. The main wire also runs to that bus. The bus currently has those two wires, main power positive battery and the starter hooked to it. I have a brown wire that runs from the fuse panel to the ACC pole on the ignition switch that is labeled as such. The white exciter wire and the brown acc wire seem to hooked to the same bus in the fuse panel but I cannot tell for sure as it is tough tot see it. Sorry I can't get any in focus pictures under the dash to show what is going on. 20200730_204312.jpeg

    I am pretty sure this is the bus inside the fuse panel with the Brown ACC wire and the white exciter wire. Nothing else seems to be attached to the other ends.

    Sent from my SM-G950W using The H.A.M.B. mobile app
    Last edited: Jul 30, 2020
  25. You need to physically trace the exciter wire though the fuse panel. If it's connected to anything else, that's your problem.

    As to the online diagrams that show that jumper, they're wrong. If you connect it like they show, you might as well use a one-wire alternator.
  26. If you swap the wires, it will break the alternator after a few mins.
    Get yourself the correct plug, it’s much easier to deal with.

    As far as the jumper goes, that sense wire tells the alternator how much to put out based on the voltage in the system. The wire should go back to the fuse box.
    With it jumped anything and all it can really tell the alternator is about what the alternator is gg
  27. OK thanks I will see where it goes. Would anything I have done cause the internals of the alternator to go bad and cause it to draw internally? As in do you think I need another new alternator?

    Sent from my 9024O using The H.A.M.B. mobile app
  28. I'd sort out the wiring first, if it doesn't charge you probably killed the regulator. Those are cheap to replace....
  29. OK here is where I am at. The bus in the fuse panel only has those two wires on it. It is fused to the adjoining bus on all 4 pins (I assume for switched acc) I pulled all of those fuses light still on, pulled the starter wire, light still on, , removed main power wire to alternator light stays on, remove exciter wire light stays on, pulled the red 'sense' wire off the alternator light goes off. I used the little jumper wire to make sure I didn't have a spot on the sense wire that might be pinched, as I have major disassembly to trace it by eye, light stays on. I removed the main bus from the chassis to make sure it wasn't accidentally grounding and still have a light on. The only thing that shuts the light off is unplugging the red sense wire.
  30. krgdowdall
    Joined: Apr 3, 2015
    Posts: 102

    from Alberta

    Just an illusion, but on your photo of the alternator, the copper tube appears to be touching the Battery terminal. Probably just the angle.

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