Altenator wiring question

Discussion in 'General IH Tech' started by Scoutlaw, Jan 2, 2006.


  1. Scoutlaw

    Scoutlaw Farmall Cub

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    What is the main purpose for the big blue wire coming from the back of the altenator? I know it runs to the ammeter gauge and then to the starter, but if I want to get rid of the ammeter gauge would I have the blue wire run straight from the altenator to the starter?
     
  2. Paul 3

    Paul 3 Farmall Cub

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    Scoutlaw,
    that blue wire runs like you said, from the alternator to the back of the ammeter.....and then to the I3 (if I remember correctly) position of the ignition switch, which then brings power to the fuse box so it gonna be a problem if you simply run it right to the starter :eek: :eek: :D
    If you are only looking to bypass the ammeter, and nothing else, remove it from the dash, you'll see it has two posts on the back. One has the blue wire from the alternator, the other post has a wire leading further into the dash (that's the one going to the ignition switch). Remove the blue wire and move it to the same post as the second wire (the one leading to the ignition switch). What you've done is effectively bypassed the ammeter and tuned it into a junction post for all intensive purposes.
    Disclaimer: Depending on your reasons for bypassing the ammeter (ie, upgrading to a high amp alternator, installing a voltometer, etc.) then by all means do a little more searching into upgrading the wiring both for **SAFETY** and performance.
    Lot's of guys, myself included, have bypassed the ammeter and added a voltmeter instead for numerous reasons including upgrading to a higher amp alternator or simply improving on the stock wiring.
    Use the advanced search function and look for write ups including the word 'alternator'. In addition look for any alternator write ups from Doug Shailor, which can also be specified under the advanced search function, there as good as gold and he's got more info on the subject than you can possibly imagine.

    Hope this helps

    Paul
     
    Last edited: Jan 3, 2006
  3. Doug Shailor

    Doug Shailor Guest

    Paul,

    While your heart is in the right place the above info is not correct and in fact dangerous.

    I'm going to make an "executive decision" and include a copy of the article I wrote for the BB Newsletter and include it here. It's time to include this info in the FAQ section so here it is:

    Volt Meter and Charging Indicator Light

    by Doug Shailor

    Whenever anyone installs an alternator in an SII that has a rating higher than 63 amps (the largest available from the factory), the charging circuit and wiring needs to be upgraded and the factory ammeter should be bypassed. Neither the factory wiring nor the ammeter are designed for more that 63 amps. Not rewiring is setting the vehicle up for a potential fire.

    The bypassed ammeter needs to be functionally replaced by a volt meter and a charging indicator or alternator "idiot" light is also recommended. The volt meter monitors charging voltage. This is usually about 14.3v when the alternator is operating normally but battery voltage (12.6V or less) when the alternator is not charging. These values assume the alternator, battery and wiring to be in good condition.

    When an alternator stops charging no matter what the cause, the indicated voltage will drop and can be noticed if you are actually reading the volt meter every time you look at it. However, many of us have the volt meter mounted lower than the normal line of sight. The idiot light will provide an instantaneous indication of a failure, assuming it is mounted conspicuously, without having to read the volt meter while driving down the road or negotiating difficult trails off road. You can continue running the engine off the battery for a while but doing so drains it fairly quickly. Stopping the engine as soon as the problem occurs will give you the chance to fix the problem before the battery charge has dropped too low to start the engine again.

    When rewiring for a high amp alternator, first remove the old 10 gauge wire (circuit #2) from the alternator "Bat" post, you wont need it any more. Run a new wire from the "Bat" terminal on the alternator (using 8 or even 6 gauge is highly recommended) and connect it to either the "B" terminal on the starter solenoid or preferably directly to battery positive. The battery cable running from battery positive to the solenoid "B" terminal will remain in place. You might want to upgrade this battery cable to a larger gauge (smaller number) while you are doing this. Other alternator output routing approaches might be taken when a hot start solenoid and/or a dual battery isolator system is used but I'll leave that subject for another issue.

    In all cases you want the alternator "#2" terminal to have positive 12v when the key is off. You accomplish this by running a short 14 or 12 gauge jumper from the alternator "Bat" terminal to this "#2" terminal in the white two wire alternator connector. By the way, from what I have read, it is not a good idea to convert to a one wire alternator. Check the M.A.D. Enterprises web site for tons of great technical information on alternators including an argument against using a one wire alternator. Here is the link: http://www.madelectrical.com/. I learned how to wire an idiot light from the owner, Mark Hamilton.

    [​IMG]
    Fig. 1 -- Alternator Wiring Diagram

    You will still need to run a wire into the dash to power the fuse panel. I would run it from the battery positive or perhaps another source if you have a hot start solenoid or dual battery system. I ran a new fused 10 gauge wire to the ammeter negative post (the same side as the circuit #14A wire which powers the fuse panel), removed the old blue 10 gauge wire (circuit #2) from the ammeter negative post and removed the old blue 10 gauge wire (circuit #14) from the ammeter positive post . This essentially bypasses the ammeter but uses the negative post as a junction. It is handy to do it this way as you don't have to create a new wire (to replace #14A) to power the fuse panel. Just make sure you disconnect the old blue 10 gauge wire (the other end of circuit #14) from the "B" terminal of the starter solenoid or you will have a live wire under the dash looking to short out and start a fire.

    The remaining wire to the alternator is the idiot light circuit. It starts at the I3 terminal in the ignition switch. The I3 terminal is the only terminal in the switch that is hot when the key is in the Run position but it is not hot in the Start and Accessory position. I3 currently has a special orange 20 gauge resistance wire attached to it that runs to the alternator #1 terminal through a couple of connectors including one of the infamous bulkhead connectors. This wire is to be removed from the I3 terminal and you will also disconnect the other end at the alternator # 1 terminal too. You might want to label the wires you removed even though you wont be using them or cut them out altogether . It's just a good practice if you ever forget what you did. Any future owner will appreciate it too.

    The ignition switch is located on top of the lower portion of the steering column inside the cab. It is held in position by two hex head screws. The mounting flange has oblong slots for these screws in order to position the switch properly so try to mark it's position before you remove. Worst case is the starter wont quit when the engine is running. That happened to me.

    Be patient and careful removing the connectors blocks (there are two) from this switch. Part of the black one overlaps part of the translucent one so the black one has to come out first. If you break a connector block a new set of blocks including short wires already crimped to the proper terminals is available from NAPA. It's part number SC6520 for around $12. I had to order mine but it was there the next day.

    You will need a new 5/16" wide female spade connector for the I3 terminal. This is an odd size as most, if not all, of the others are a 1/4" wide. A 3/8" terminal is too big to fit in the connector block. These 5/16" terminals are hard to find but they are out there. However, you may have to buy a small bag of them. There is one included in the NAPA part mentioned above.

    [​IMG]
    Fig. 2 -- NAPA #SC6520 Kit

    You will also need an incandescent light (it must not be an LED) and red is recommended. CONDUCT TITE! part #85938 is a good choice because it is about 1/2" in diameter and has 1/4" male spade terminals allowing it to be disassembled if necessary. The CONDUCT TITE! brand is available at many auto parts stores.

    The rest is easy. Run a new 16 gauge wire from the I3 terminal to one side of the incandescent light and another new 16 gauge wire from the other side of the light to the #1 terminal in the white two-wire alternator connector. New two-wire alternator connectors are available at most any auto parts stores if you need or want one. It's a good idea to use the same color wire on both sides of the light and label both ends. I like the idea of making a simple drawing of all these new circuits and placing it in your IH service manual in the electrical section.

    One choice of a mounting position for the idiot light is between the factory ammeter and the oil pressure gauge. There is plenty of room to drill the hole for above mentioned light part number. That's where I put mine so it is right in front of me. It's the red light between the gauges.

    [​IMG]
    Fig. 3 -- Charging Indicator Light, Completed Installation

    Should the alternator quit working the light will come on immediately and you don't have to read the voltage off the voltmeter which is especially difficult to do at night.

    Wiring the volt meter is also easy. Run a new 16 ga wire off the I3 terminal to the 12v connector on the volt meter and a new 16 ga wire from the volt meter ground connector to a very good ground. If your volt meter has a light you will want to connect that to the dash light circuit as well. If you want to get the very best reading on available voltage in your new charging system then you should read the "Remote Sensing" section on the M.A.D. web site.

    There may be other items you want to run off the I3. Keep in mind it is only hot when the key is Run position. I have a couple of things wired into it. I ran a fused 12 gauge wire from I3 to a small junction block with a single post and run wires off this junction block to the things that I want to be on only when the key is in the Run position.
     
    Last edited by a moderator: Jan 3, 2006
  4. Doug Shailor

    Doug Shailor Guest

    The big blue wire is the output of the alternator.

    You don't mention which vehicle so we can only answer generally, in this for an SII.

    The blue wire from the alternator is circuit #2. It is attached to the negative side of the ammeter. There is another circuit wire on that terminal too (#14A) and it feeds the dash. If you move #2 to the starter solenoid then you would not have any power to the dash including the fuse panel. It would charge the battery (if you could start the engine) but that all. You would still have to get power circuit #14A.

    Now if you install a remote starter solenoid and connect the to the same side as the batter cable cable then you could run a new 10 or 8 gauge wire to the negative side of the ammeter and disconnect both ends of the #14 circuit (ammeter positive and starter solenoid). In effect you use just use the negative post as a junction.

    If you want to remove the gauge altogether remember is has the fuel gauge in too. Then you would have to run a new wire to the end of the #14A and butt splice which I don't like to do in high current circuits or figure a way to connect the new wire to the battery feed connector.

    You really should have the electrical diagrams to be messin' with this kind of wiring.
     
  5. nickl

    nickl Farmall Cub

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    Doug,
    Just moving the alternator output wire to the starter or battery will work because there is a wire (#14-10) going from the starter to the ammeter and will power the fuse box as long as the ammeter is left in. The ammeter will be useless because you have bypassed it for battery charging. If the ammeter is removed You can connect wire 14-10 to wire 14A-10 with a small bolt and shrink tubing or electrical tape. This does nothing to upgrade the old wires but it will function and keeps the battery charging current out of the dash.

    I agree with the electrical diagram part!!

    Nick
     
  6. Paul 3

    Paul 3 Farmall Cub

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    Doug,
    thanks for the catch. I should have known better. The article you posted was one of the first I used when I rewired my 78 Scout II for a voltometer and remote starter solenoid. That and a couple dozen calls to Mark at madelectrical and I got it up and running. After you pointed out the mistake I made I went downstairs broke out my wiring diagrams and the shop manual and realized that I had been incorrect in my post. :( I guess it was a good thing I put my 'Disclaimer' in there huh?

    Thanks again,
    Paul
     
  7. Doug Shailor

    Doug Shailor Guest

    Nick,

    I agree, however, I suspect the ammeter will indicate backwards since the juice is coming into the positive side instead of the negative side. And IMO doing it that way is not really bypassing the ammeter since the current would still have to flow through the meter to get to the #14A circuit.

    Now if you moved the #2 circuit wire to the negative post then what you say is also correct and the ammeter is bypassed.

    However, I don't care much for either solution as you are still using the old wire going through the old bulkhead connectors. The latter cause so many problems as they get older that I always recommend bypassing them too, especially for the high current wiring.
     
  8. nickl

    nickl Farmall Cub

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    I agree with you Doug. Its not the best solution. I just wanted to point out that it will work and you get the benefit of the battery charging current not flowing under the dash and through the ammeter. The current for everything else still does though.

    Nick
     
  9. Neal Gray

    Neal Gray Farmall Cub

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    This would be the best advice I have gotten but with nooooooo pictures it is confusing 14a? 14? #2wire need the pics please. I was trying to put a fuse inline by the starter and the dang battery cable fell back on the battery post pop there went the ammeture and the internal volt on the 37amp alt. Ticked but my stupidity for not tying it up so wire tied and moving forward have a 79 parts scoutii with a/c for my 72 pulled the alt off the 79 and the amp gauge figured they were in the same rig so keep them together, Now with everything wired back factory the charging system is well above middle on the charging and when you pull the lites on instead of discharge it shows charging harder??? I checked and the alternator does have smaller double groove pulley than the 37 amp did the plastic plug in the alt does not have a tang on it so can you put the plug backwards? please Doug can I get your write up with pics I would very much like to follow it to the letter and bypass the meter and pu t lite with voltmeter. the previouse owner had installed the ford starter relay for the kc lites but i havent touched it. can you please help because now when you feel the blue niwres at the bulk head they are hot sooooooooooooooo I am not running this until all wiring is corrected! Wich sucks because I LOVE my Scout.
     
  10. RobertC

    RobertC Binder Driver

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    There are "articles" on the web on how to wire a "new" altenator into an "old" electrical system.

    Try Madelectrical in Google... for one

    But, it seems you have other problems -- bad altenator? Maybe it is just your wiring.

    Not sure why you need an inline fuse to the starter, but I do not know "electrical" that much.
     
  11. Eric VanBuren

    Eric VanBuren Lives in an IH Dealership

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    The simple fix is to bypass the ammeter with a 8ga or better wire from the alternator B+ stud to the B+ stud on the starter. Here are a couple of diagrams another member did hope this helps.

    [​IMG]

    [​IMG]

    Personally I am not a big fan of fuesable links, not very trail servicable, I'd suggest a inline fuse Maxi, ANN or ANL for the higher current draws or a circuit breaker, the non self re-seting type.
     

    Attached Files:

    Last edited: Apr 11, 2009
  12. RobertC

    RobertC Binder Driver

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    Eric, Thanks for the diagrams. I printed them and filed them with other info.
     
  13. Neal Gray

    Neal Gray Farmall Cub

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    Thank you very much for the diagrams, will help alot, will Update next weekend when I put it all together. Have a run to do tomorrow so I wont get to it this weekend like I had hoped. Thanks to you all. I will update when I have a running Scout again:)
     

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