Quick Wiring Question- Heater and Lighter

Discussion in '1947-1954' started by Haasman, Oct 10, 2019.

  1. Haasman

    Haasman Member

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    I am wiring my '51 3100 with a simple OEM style harness. Where should I connect the heater blower motor and lighter? It seems everything routes through the headlight switch. Wondering if there isn't a better way? Thinking of eventually adding a radio. All three could run off the same 12v source?

    Any suggestions/comments?

    Thanks in advance.

    Haasman
     
  2. Bill Hanlon

    Bill Hanlon Member

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    The heater fan motor could take a lot of current and I prefer to not have that current going through the ignition switch. If you are using an OEM style harness I assume that you are using a stock 3 terminal ignition switch and ammeter and would prefer it to measure the complete electrical system including the heater and lighter socket. If so, I'd wire it like this.

    Get a 30 amp self resetting breaker like this: CURT 30-Amp Universal Circuit Breaker-58361 - The Home Depot and a 40 amp Bosch style relay like this: Pico Relay and Connector Kits 5591PT
    Make sure it comes with a socket/pigtail.

    Using 12 gauge wire, connect either terminal of the circuit breaker to the terminal on the ammeter that does NOT connect to the battery. Keep this wire as short as you are comfortable with, considering where you will mount the circuit breaker.

    Connect two wires to the other side of the circuit breaker. One wire will go to the lighter socket, the other to pin 30 of the relay.

    Connect a wire from pin 85 on the relay to ground.

    Connect a wire from pin 87 on the relay to the heater switch.

    Connect a wire from pin 86 on the relay to the accessory lug on the ignition switch. Use the ignition lug if it is easier to work with.

    Red below is existing, while black is the new stuff. When you add the radio you could power it from the same wire as pin 87 on the relay.

    [​IMG]
     
    Last edited: Oct 10, 2019
  3. Haasman

    Haasman Member

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    Thank you Bill! Really appreciate you taking the time to post this.

    Haasman
     
  4. Bill Hanlon

    Bill Hanlon Member

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    By the way, if you add a radio with memory connect the memory power wire where the lighter connects.
     
  5. Haasman

    Haasman Member

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    Good reminder! Thanks again Bill.
     
  6. Haasman

    Haasman Member

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    On my ’51 3100 I plan for it to have the following:

    -Bed roll LED lights, left and right: Illuminated brake and turn- 3 wires

    -Taillights, stock housings with LED panels:
    • Left side: Tail, Brake, Turn and License
    • Right side: Tail, Brake and Turn
    I would like recommendations on wiring, best practices (ideally) for connectors. And what is a good way of connecting the bed roll wiring, to the taillights and ultimately to the wiring loom.

    Ideally these connections would facilitate ease of removable in case of service and body repairs.

    Finally I plan to route the taillight wiring through flexible chrome conduit into the rear box section of the rear bed panel.

    Suggestions and recommendations welcome and appreciated.


    Haasman
     
  7. Bill Hanlon

    Bill Hanlon Member

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    If the brake and turn LEDs are separate in the upper (bed roll) are they the same brightness? Brake and turn on one side are typically provided by the same filament in a regular bulb. Are you planning two different LED circuits on one side (equivalent of a two filament bulb such as a 1157)? If so, you might have a hard time seeing the turn lamp when the brakes are applied. I'd just use a single circuit LED in each bed roll and connect it to the same single circuit that provides brake/turn function in the stock housing below it. I'd do the brake/turn light as a single circuit in the lower stock housing as well.

    When I put bed roll lamps in my '57 (flat top bed) I snuck the wiring into the rear stake holder and then down under the bed. I don't know if that would work on your slant top bed.

    License and tail functions are typically provided by the same circuit (and by the same bulb filament in a stock housing).

    If you are combining turn and brake light functions there are only 3 wires and ground required from the front of the truck to the rear. I'd use a 4 pin trailer connector like this to connect the rear harness to the front of the truck.
    [​IMG]
    They are cheap and easy to deal with. Walmart and any FLAPS will have them. Hook it up with the connector with 1 exposed pin to the truck and the other connector to your new harness in the rear. That way, when the harness is disconnected you don't have to worry about exposed pins having voltage on them and possibly touching ground. If you need 4 circuits (and ground) there is a 5 pin version.

    While you are working on your rear harness you might consider are trailer plug just in case you ever decide to tow with your truck. I put in one like this
    [​IMG]
    because a lot of trailers use this type. Some of the pins will not be used in your (or my) case. Walmart and any FLAPS will have them.

    Solder all splices.

    Use heat shrink over any splices you make. Northern Tool and Harbor Freight both have cheap heat guns that work.

    Cover any exposed wiring run. You could use (not my favorite, but easiest) split loom
    [​IMG]

    spiral wrap
    [​IMG]

    or just cover the exposed run with heat shrink. But if you use heat shrink (what I like to use), be SURE that you slip the heat shrink onto the wiring BEFORE putting the connector on the end. I couldn't tell you how many times I've made this mistake myself.

    Building on a scrap lumber frame can make assembling your wiring harness easier.

    And remember what my Dad used to say: "Cut it off three times and it is STILL too short."
     
    Last edited: Oct 18, 2019
    RidesWithYah likes this.
  8. Haasman

    Haasman Member

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    Thanks again Bill. Always appreciate you inputs.

    I am seeing the wiring, as simply as possible with much ass you described above. I have the loom from basically the headlight switch/turn-signal with 4 wires coming to the left rear of the truck. There it will connect with the both the wires from the bed roll LED and tail light assembly. Then the loom continues underneath the rear of the truck over to the right rear.

    It's the left rear where I will have all these multiple connections. Thats what I am trying to figure out.

    ... and in addition your suggestion of including a trailer connection.

    Once completed I'd like to shove everything up into the rear square section and hide it all.

    Haasman
     
  9. RidesWithYah

    RidesWithYah Member

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    Your original post says everything runs through the headlight switch, and that is how the original wiring was.
    Bill's reply using relays keys off of the ignition switch.
    Either route will work... the headlight switch is powered directly from the battery, so is hot all the time (you can run the heater motor with the ignition off). Using the ignition switch to power your relays lets you shut everything off with the key so you don't forget anything and run the battery down.

    I wholeheartedly agree with the use of relays to reduce the amount of current running through either the headlight or ignition switches.
    Generally with OEM stuff converted from 6 to 12 V you're fine (higher voltage requires less current for the same wattage);
    but the Repro replacements aren't as good quality as the originals, *and* we tend to add a lot of extras requiring power that weren't available in 1951 (subwoofers, anyone?).

    And, please post more pictures of your truck. :)
     
  10. Bill Hanlon

    Bill Hanlon Member

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    What are the 4 wires?
     
  11. Haasman

    Haasman Member

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    They are the wiring loom going to the back of the truck, routed along the frame. I believe there is a wire for: illumination, turn, brake and the final one, I am not sure of. (I am an amateur at this truck wiring). I purchased this loom from our host.

    Attached is the wiring diagram I received with the wiring loom.
     

    Attached Files:

  12. Bill Hanlon

    Bill Hanlon Member

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    Too bad that documentation from our host doesn't have a real wiring diagram.

    Your truck didn't come with turn signals (or a horn relay). Where did they come from?

    Does your turn signal switch have 6 wires? Most do. If so, there needs to be a minimum the following wires running to the back:
    a. running lights, comes from the headlight switch
    b. left turn signal/brake light from the turn signal switch
    c. right turn signal/brake light from the turn signal switch
    d. ground (optional - maybe you'll ground to the frame)

    Do the taillights have separate wires for brake and turn? Most don't.
     
  13. Haasman

    Haasman Member

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    Bill and RidesWithYah- really appreciate you thinking this through with me.

    The explanation of the use of a relay really makes sense. Being able to turn everything off at once and not running a lot of current through the ignition or light switch seems a good idea. Had throught about installing some kind of USB charger

    I bought the truck with turn signals and a horn. My turn signal does have 6 wires.

    I agree, the ground has always been frame, body etc in my understanding. Speaking of which, what's the typically best way to ground the truck body to the frame.

    Haasman
     
  14. RidesWithYah

    RidesWithYah Member

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  15. Haasman

    Haasman Member

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    I had been told to avoid braided because of corrosion .... and to use an insulated one instead. I am fine with the braided. Just found some of the jagged washers that lock into metal well to ensure a good connection.
     
  16. Bill Hanlon

    Bill Hanlon Member

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    Still need 2 questions answered by you in order to give good answers to your questions.

    1. What are the 4 wires you talked about here?

    2. Do the LED taillights have separate brake and turn wires or are both functions covered by one wire? Same question for the LEDs in the bedroll. Do you have pointers (URLs) to the LEDs so I can look for myself?
     
  17. Haasman

    Haasman Member

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    Sorry Bill, life distractions for a few days.

    So #1: there are four wires as part of the wiring loom from the firewall back to rear lights. Not sure why there are four conductors.

    #2: I believe the correct answer is LED taillights and brake lights are covered by one wire.

    Attached are the instructions for the LED tail lights and bed roll LED lights.

    Thanks Bill.

    Haasman
     

    Attached Files:

  18. Haasman

    Haasman Member

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    Additionally, I could use some suggestions on how to connect all these wires at the back of the truck:
    1. Bed roll lights, 3 wires
    2. Left/right taillights 3 or four wires
    3. the wiring loom coming down the frame rail to the left taillight/bedroll and then attach to the right taillight.
    I am wondering whats the cleanest way to these 9 or 12 wires?

    Should I just do each wire, one to one or gang connect them? Ideally like to be able disconnect them if a repair is needed but also make is a clean install. Wondered about using a wiring block. Advice?

    Haasman
     
  19. Bill Hanlon

    Bill Hanlon Member

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    You are going to need to know what each of the 4 wires is in order to make the lights work.

    Can't be. Turn signal and brake light can be (and probably are) covered by one wire to the left rear and another wire to the right rear. Taillight wire from the front will power taillight on both left and right rear.

    The wiring diagram that accompanies the LED bedroll lamps does not show the colors of the wires. Need to get this info from Mar-K.
     
  20. Bill Hanlon

    Bill Hanlon Member

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    I read the bed roll LED installation info and it made no sense to me. You need to identify what each wire does.

    Find 3 small nails or screws that fit into the crimp connectors snug enough to stay in by themselves without crimping them in. Put one in each wire's crimp connection.

    The black wire is easy. It is ground. It attaches to the case of the lamp assembly.

    Hold the black wire to the negative post of any car battery.

    Hold the white wire to the positive post of the battery. Observe what happens to the lamp.

    Remove the white wire from the battery.

    Hold the red wire to the positive post of the battery. Observe what happens to the lamp.

    Leaving the red and black wires connected, hold the white wire to the positive post of the battery. Observe what happens to the lamp.

    Compare the difference in observations.

    Let me know what happened.
     
    Last edited: Oct 24, 2019

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