CJ/YJ/FSJ and other jeep head light harness upgrade FL

Discussion in 'Early CJ Vendor Directory' started by jimbos76cj, Aug 4, 2013.

  1. Aug 4, 2013

    jimbos76cj New Member

    St.Cloud FL
    Jul 25, 2013
    Ive received enough questions that I figured Id put this up. They fit 76 and up CJ's really well so I dont see why they wont work in the older models as long as they use the 3 prong headlight

    I am offering pre made plug and play head light wiring up grade harness for CJ’s, YJ’s with FSJ to come in the near future. Why should you upgrade? To answer this we need to take a look at how your headlights get power in your Jeep.
    Step 1. Power leaves your battery and enters your fuse block.
    Step 2. Every thing in your jeep begins to take its power from the fuse block.
    Step 3. What ever power is not being used to operate the rest of the systems in your jeep is then routed to your head light switch where it is divided up between your head lights and running lights.
    Step 4. The left over power then leaves your head light switch and enters your floor/column mounted dimmer switch (High beam switch)
    Step 5. Once it leaves your dimmer switch it enters your main fuse block then exits through your engine compartment pig tail from the fuse block before heading out to your lights through either 16-18 gauge wire. It ends up going through your head lights and grounding to your grill

    While you will get power to your head lights in this manner you may not get the full volts required to operate the bulbs at their potential.
    Here is a excerpt from Daniel Sterns Lighting page
    10.5V : 510 lumens
    11.0V : 597 lumens
    11.5V : 695 lumens
    12.0V : 803 lumens
    12.5V : 923 lumens
    12.8V : 1000 lumens
    13.0V : 1054 lumens
    13.5V : 1198 lumens
    14.0V : 1356 lumens
    14.5V : 1528 lumens

    In a real world test on a YJ the output prior to the mod was 11.2 volts low and 10.6 high. After the upgrade the volts were 14.6 for both.. The light out put has greatly increased.

    So to see if you would benefit from this type of upgrade with the jeep running probe the back of the head light sockets with a multi meter to see what your volts are at the socket. Normal seems to be between 12.0 and 11.5 that’s a 20 to almost 30% decrease in lumens from your bulbs. If your getting 12.8 or close to it and your wires are not getting warm from the current draw then you do not need this upgrade.

    Other reasons.
    Wire diameter. I’ve seen head light wires running as low as 18 ga wires.. 10-15 amps is a lot of power to go through a 16ga wire.

    Switch resistance. Ever read about some one having a head light plug melt at the switch? That’s because the wiring and plug are not designed to handle the amp draw of the head lights.

    Age and wear. With the newest CJ being at least 27yrs and YJ’s being between 26 and 18 yrs old the contacts are becoming more corroded and causing more resistance which leads to heat build up in the wires and switches.

    Switch failure. If either of the switches fail from the 10-15 amps being drawn through them then you have NO HEAD LIGHTS.

    Grounds. First thing we look at for a electrical issue on Jeeps?? The grounds. Old, loose. Dirty grounds will cause power reduction to the head lights.

    How does this upgrade solve these problems?
    It will increase the diameter of the head light wires to 12ga
    It will reduce the amp draw through the switches to less then 1 amp
    It will replace the worn, damaged, and corroded connectors with new connectors and terminals

    Now on to the how they are built
    First I start off with 2 very reliable AGT bosch style relay.
    2x 12 ga water proof fuse holder is added to added with both the ring terminal and new relay terminals being soldered on. By using 2 fuses it allows either the high or lows to be used if the other one fails.
    The relay switch wire is made of 2 new 16 gauge wires. One end has new relay terminals crimped and soldered on and the other has 2 new Packard 59 male terminals crimped and soldered and inserted into a male head light connector
    The new 12ga wire for the head lights is crimped and soldered and placed in the relay while the other end gets new HD Packard 59 female spade crimped and soldered and inserted into new female head light connectors. For the ground wire a new 12ga wire is crimped and soldered then added to the head light plug. Instead of having the wire hooked to the grill where it meets a lot of resistance it is routed either to the engine block ground or directly back to the battery to complete the circuit.

    Time: 20-30 minutes
    Tools required :
    ½” socket (battery terminal removal)
    5/16 drill bit and drill
    Philips screw driver
    1)Locate a 3x3 area on the passenger side fender to mount the relays. Set relays on fender and mark both mounting holes. Drill both holes with a 5/16 bit. Sand around one of the holes so that relay ground wire (short black) can attached with the relays. Locate mounting place for fuse holders and mount the same way
    2)Attach the power wire(s) from the relays to the starter solenoid lug that has the batt POS cable attached
    3)Hook the ground wire to either the negative batt cable directly of to where the ground cable hooks to the engine block. Verify the mounting location is clean and free of rust and paint.
    4)Remove passenger side head light plug (bulb removal may be needed to route and attach wires) and connect the male head light plug to the passenger side stock female plug
    5)5 Connect the new head light sockets to both bulbs. The wires should be long enough to route to the bottom of the grill.

    Test both High and low beams for operation.

    Cost.. for a standard CJ/YJ harness im asking $60 shipped.. I only make between 12-15 dollars from it since I use the 12 ga wire and replace all the terminals in the relays.

    I can also make the wires to any length you like.. since I make it all from scratch I can adjust it to any length you need.

    Heres a few pics with explanation why this is a better system then others offered.
    Relays are the same as used by most building them

    When I receive the relays they are pre wired with 16 ga leads.. I remove and discard all the stock leads except for the ground wire. The wires that carry all the volts are upgraded to 12ga The wire on the right is 16 and left is 12.. big difference

    LEft to right is the new connectors that get used. ring connector for the ground and power, ring for the relay ground, spade terminal for the relays and new packard 59 terminals for your head lights.. No reusing any terminals or wires.

    Next connector is this reducing butt connector. Admittedly I don't like using but connectors but these are specially designed to take 2 12 ga wires and reduce it to 1. I tried to figute out another way to run em with out the crimp joint but there no way with using the 12ga wires. After crimping them I solder all 3 butt connectors then seal em with double wall shrink wrap.

    I took these next series of pics to show how tight the crimp is when used with a proper set of crimpers

    I stripped extra conduit off these to show tight they get

    2 water proof fuse holder are installed.. Why 2? Its more of a safety factors.. if one of the fuses blow you can still drive with the other system. I could save a few bucks by making it with one fuse but id rather build in a little extra safety.


    Then I build switch wire for the relays to turn the lights on and off. All new 16 ga wire is ran to a new male headlight terminal plug

    Heres a white head light plug plugged into the socket to give you an idea of how it goes together.

    Heres a completed kit.. The grey ends are new head light plugs I will be going with orange porcelain with my next batch .. the Black is the switch socket.

    Well theres my long explanation.

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