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Engine Wiring - Please Help

Discussion in 'Intermediate CJ-5/6/7/8' started by mgtmel, Sep 17, 2007.

  1. Sep 17, 2007
    mgtmel

    mgtmel Mountain Goat Mel

    Oregon
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    Sep 1, 2006
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    Ok, more questions as I'm nearing the finish line on my 79 CJ5 rebuild. We are installing a brand new "painless" wiring harness. The under-dash harness installed perfectly without a hitch. Now we are trying to install the engine harness. The wiring diagrams in the instructions show about 5 different possible setups for the ignition control module-coil-starter relay-starter motor connection. My Jeep looks like it has a mixture of two of these setups. I will first post pics of my components, then the two diagrams that are the closest match. Basically, our problem is that my ignition control module (Motorcraft) has two adapters coming out of it that don't match up to the coil the way the diagrams show. Up to this point, every piece that has been inspected on this Jeep have all been original - no homemade or hybrid parts on this guy. So why the wiring mystery? Please see the pictures and let me know if there are any better diagrams out there that are specific to a 1979 CJ5 with the AMC 304. Here is my ignition control module and my coil. Thanks for any help.:?
     
    Last edited: Jun 13, 2008
  2. Sep 17, 2007
    mgtmel

    mgtmel Mountain Goat Mel

    Oregon
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    OK, it won't upload the rest of the pics, but my starter relay and starter motor are pretty basic. The starter motor is the kind with the solenoid built-in on top of the motor. Thanks.
     
  3. Sep 17, 2007
    fuzz401

    fuzz401 New Member

    lancaster pa
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    none of the factory starters had a relay on them only on the fender - what kind of starter do you have??
     
  4. Sep 17, 2007
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    The big bulge on the starter is not a relay. It's a motor that throws the starter gear into the flywheel. You need a fender-mounted relay.
     
  5. Sep 17, 2007
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    The ECU you show is a Motorcraft Duraspark type. The oil can coil (like you show) was used with the Duraspark on Jeeps. You're missing the under-hood harness and plugs that mate to the coil and ECU.
     
  6. Sep 17, 2007
    mgtmel

    mgtmel Mountain Goat Mel

    Oregon
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    I never said the relay was on the starter, I said the solenoid was on the starter. The relay is mounted on the fender. I'm sorry if I was unclear. I have the entire harness, but it did not come with the male adapters to plug into the females on the ignition control module. Just plain-jane wires with no connectors of any kind on the ends. I still have the original wiring harness with these old connectors, but the wire colors coming out of these connectors don't match the new ones. And the diagrams included in the instructions show two kinds of systems: One with my kind of control module and a starter with an external solenoid, or a different module with my kind of starter with an internal solenoid. That's why I'm wondering how to wire my module to my coil to my relay to my starter/starter solenoid. The diagrams aren't very helpful. I also have Chiltons which is extremely basic and is even more unclear than the painless diagrams. Any ideas where to find a specific 1979 CJ5 AMC 304 engine wiring diagram? Thanks.
     
  7. Sep 17, 2007
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    The relay is a solenoid. The starter solenoid is a relay. There's no solenoid on the (correct) starter.
     
  8. Sep 17, 2007
    mgtmel

    mgtmel Mountain Goat Mel

    Oregon
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    OK, forgive me because I'm new to all of this, but I assumed that the starter I have has an internal solenoid, and the small round unit with two posts mounted on the fender is the starter relay. I didn't realize that a relay and solenoid are the same thing, I thought they provided two different functions. Ok, makes sense to me, but that sort of goes against the diagrams provided with the new harness. My dad and I are just going to lay the old harness out on the ground and play detective. Question #2: The new harness includes a "ballast resistor". I haven't a clue what this does, and I'm 90% sure my CJ did not have one before. Do I definitely need this if I didn't have one before? Thanks again for the help.
     
  9. Sep 17, 2007
    JeepHammer

    JeepHammer New Member

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    Let me see if I can help you out...


    Assuming you want to use your factory DuraSpark module and factory Motorcraft distributor, and factory Delco SI series alternator,

    Starting & Charging,
    http://www.JunkYardGenius.com/charging/IMAGES/SIaltwire01.gif

    Ignition System,
    You WILL NEED a resistor for the ignition, Wire or Pot type, at least 1.35 Ohms, or your ignition module won't live.
    http://www.JunkYardGenius.com/ignition/jeep/IMAGES/ignitionrun01.gif
    http://www.JunkYardGenius.com/ignition/jeep/IMAGES/DuraSpark01.gif


    This would be the absolute correct way to wire your off road vehicle for starting & charging.

    Battery & Starter cables at least 4 Ga. and preferably 2 Ga.
    Fine Strand Welding cable is better than so called 'Battery Wire'.
    Battery terminals & solenoid/starter terminals solid copper with cadmium plating, NOT LEAD.

    Alternator 'Batt' wire and dedicated ground wire should be at least 10 Ga. or 8 Ga. if you can find it easily.

    http://www.JunkYardGenius.com/charging/IMAGES/Groundpost01.gif
    http://www.JunkYardGenius.com/charging/IMAGES/Groundpost02.gif
    http://www.JunkYardGenius.com/charging/IMAGES/Battery01.gif
    http://www.JunkYardGenius.com/charging/IMAGES/Battery02.gif
    http://www.JunkYardGenius.com/charging/IMAGES/Altwire01.gif
    http://www.JunkYardGenius.com/charging/IMAGES/Altwire02.gif
    http://www.JunkYardGenius.com/charging/IMAGES/Altwire03.gif
    http://www.JunkYardGenius.com/charging/IMAGES/SIdiode01.gif
    http://www.JunkYardGenius.com/charging/IMAGES/Altwire04.gif
     
    Last edited by a moderator: Sep 18, 2007
  10. Sep 17, 2007
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    The terminology is confusing. No need for forgiveness - keep asking questions. That's why we're here.

    Technically a solenoid is defined as wire wrapped around a cylinder. If you've ever wrapped wire around a nail to make an electromagnet, that's a solenoid. If you wrap wire around a toilet paper tube and apply battery power, you'll still make a solenoid and an electromagnet. A nail will be drawn into the center of the tube due to the shape of the magnetic field.

    Thus the solenoid is a type of linear electric motor. Power on, and an iron slug is pulled into the middle of the solenoid by the magnetic field. This kind of motor is used for lots of different purposes, including relays. On your Jeep, the starter relay that goes on the fender uses a solenoid to make the motion that closes the contact. Thus it's both solenoid and a relay, and called different but equivalent names - starter solenoid, solenoid, starter relay.

    Some GM starters do have solenoids mounted on them. In that case, the solenoid is used both to close the starter-mounted relay, and as a motor to move the starter gear into the flywheel.

    Sorry to be brief in the previous posts, but I try to make my answers short and to the point. I can write more text if you prefer.
     
  11. Sep 17, 2007
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Not sure the Duraspark module needs a ballast resistor. If it has internal current limiting, then it doesn't need one. BuildYOur4x4 has a pretty nice article on wiring the Duraspark. http://www.buildyour4x4.com/index.php?id=26 Shows the TFI coil, but you may need a ballast resistor with the oil can coil (pictured above). It won't hurt to use it, except that your spark voltage will be lower if you do. Do you have the original 1979 wiring diagram? It will show a resistive wire (in place of the ballast resistor) if you need one.

    As I recall, your engine came from a '77 or '75 Jeep and was equipped with the Prestolite ignition. Pretty sure you cannot use the Prestolite distributor with the Duraspark ECU - you need a Duraspark distributor to go with the Duraspark module.
     
    Last edited: Sep 17, 2007
  12. Sep 17, 2007
    fuzz401

    fuzz401 New Member

    lancaster pa
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  13. Sep 17, 2007
    mgtmel

    mgtmel Mountain Goat Mel

    Oregon
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    Thank you very much, guys. I printed everything out and I'll try and make sense of it tonight.
     
  14. Sep 17, 2007
    JeepHammer

    JeepHammer New Member

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    Technically, a wire 'Spooled' (a technical term) forms a 'Winding' (another technical term).
    A winding around a ferrous metal core is an electro-magnet.

    An electro-magnet can be used in a number of ways...
    If it has a hollow core, a ferrous metal rod can be drawn into the electro-magnetic core to produce mechanical movement from electrical energy.
    This is often refered to as a 'Solenoid', but actually isn't unless the ferrous metal rod drawn into the magnetic core actually activates something or produces a mechanical 'Job'... Like opening a valve or moving a lever for something.

    The 'Solenoid' used on the fender of the Ford type starters actually isn't.
    It's a 'Relay'.
    Low power to switch high current is a 'Relay', not a 'Solenoid' by definition, since the electro-magnet in the 'Solenoid' doesn't do any any mechanical work, it's 'Technically' considered a switching relay.

    The term 'Solenoid' is a left over from the days of manual switching, usually a foot pedal or 'button' on the floor that was connected to a rod, that moved a set of electrical contacts connected to the starter.
    Since that was Mechanical movement over Electrical energy, it IS a solenoid.

    GM starters use a true solenoid on their starters.
    The electro-magnet moves a ferrous core backwards, levering the starter drive nose out into contact with the flywheel.
    It also has a built in set of contacts for the high current required by the starter motor.

    The thing on the fender is an Electrical Relay.
    Slang refers to it as a Solenoid.
    The same way 'Bendix' is pretty much universal for Starter Drive Gear,
    'Motor' is generically used when people mean 'Engine'
    (as in 'Internal Combustion Engine'), ect.
    ...................

    The 'Box' pictured isn't a 'ECU' (Engine Control Unit) or an ECM (Engine Control Module) or a ECC (Engine Control Computer) or anything of the like.

    Smog 'Computers' would make the scene in CJ until '82 with the 258 engine with Carter BBD carb.

    The 'Box' shown in the picture is the DuraSpark Ignition Module.
    The good news is it's a factory module, the bad news is it's 25 years old...

    The one shown in the photograph is the factory module, Not an after market cheapie.
    Refer to my links on how to wire the Motorcraft distributor & DuraSpark module in a factory style harness.

    The DuraSpark absolutely needs a 1.35 Ohm resistor or larger to keep the module alive.
    -------------

    And none of this helps a guy with a wiring problem...

    mgtmel, tell me if I can help with more diagrams or explanations.
     
    Last edited: Sep 17, 2007
  15. Sep 18, 2007
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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  16. Sep 18, 2007
    mgtmel

    mgtmel Mountain Goat Mel

    Oregon
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    Wow. Again, I love this forum. Not only did I get all the help I needed, but I feel like I sat through a college science lecture for free! Just kiddin'. Anyway, timgr, I don't know who you are thinking about, but my engine is the 1979 "numbers matching" original 304. Everything in the engine bay is original (except for the carb, manifold and headers I installed) so luckily everything fits together pretty well. Once we layed the old harness out on the floor and pirated some of the original wires and connectors, things started making more sense. And now with all these diagrams, it should go smoothly. I just wish the "painless" kit would include all the connectors, clips, and better diagrams. But a frame-off rebuild on a 28-year-old Jeep wouldn't be any fun if everything was easy, right? Thanks again, everyone!:)
     
  17. Sep 18, 2007
    NorCoJeeper

    NorCoJeeper Member

    Ft. Collins CO
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    Not to muddy the waters, but a relay uses a solenoid to close a set of electrical contacts. The complete assembly is called a relay. An electromagnet that causes a core to move (ferrite by default because non-ferritic metals aren't magnetic) is a solenoid, doesn't matter if it's actually doing any work or not (although there's no reason to make this setup if it isn't going to do something useful).

    The starter relay on a Jeep is a relay, pure and simple. In the starter, there is another solenoid that pulls the drive gear into the flywheel. In the case of the starter, the electromagnetic coil is actually a field winding in the motor. The relay energizes the motor which pulls the core of the solenoid in which is attached to the starter drive pinion and overruning clutch.

    For vehicles with an integrated starter solenoid, when the starter relay attached to the motor is energized, the core of the relay both pulls the starter drive pinion into position and closes the high current contacts on the other end of the starter solenoid. The term solenoid in this case refers to pulling in the starter pinion, it's primary duty, but it also incorporates the starter relay.

    The starter relay in either case allows a small current from the starter switch to allow high current from the battery to travel to the starter motor.

    The take home info is that a relay adds functionality to a solenoid, but is not a solenoid in and of itself.
     
    Last edited: Sep 18, 2007
  18. Sep 18, 2007
    Boyink

    Boyink Super Moderator Staff Member

    Tulsa, OK
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    OK guys....enough with the technical discussions of what is or isn't a solenoid - please get it back on-topic and respond with answers to the original question.
     
  19. Sep 18, 2007
    JeepHammer

    JeepHammer New Member

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    Starting & Charging, Quick Wire Diagram.
    This is NOT the correct way to wire a Delco SI Alternator, but it will work for testing and charging the battery.
    [​IMG]

    Just trying to see if this hobby site will post linked graphics...
     
  20. Sep 18, 2007
    JeepHammer

    JeepHammer New Member

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    Ignition System,
    You WILL NEED a resistor for the ignition, Wire or Pot type, at least 1.35 Ohms, or your ignition module won't live.

    [​IMG]

    [​IMG]
     
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