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Technical Wiring diagrams and reality

Discussion in 'The Hokey Ass Message Board' started by 62rebel, Apr 11, 2019.

  1. Ford wiring....Working in a Lincoln Mercury dealership as a line mechanic one day I had to R&R a '69 T-bird turn signal switch. I didn't need to worry about wiring colors because I was just swapping the old one out for a new one from our parts department...right? I snipped all the wires at the connector and dragged them up through the column....went to "parts" and came back with the new switch/wiring pigtail. All the colors were different! And I'd already removed the old stubs from the connector! I went back to the parts counter and told them they'd made a mistake and they told me Ford made running changes on wiring colors...sorry.
    Parts books didn't show any updated wiring colors either. I had no "Rosetta Stone" to decipher the colors so I had to figure out what each wire did ....took waaaaaaaaaay over what the flat rate book gave me for the job. I'm still pissed at FoMoCo wiring........
    Last edited: Apr 12, 2019
    loudbang and Blues4U like this.
  2. 62rebel
    Joined: Sep 1, 2008
    Posts: 2,327


    Well, I'm sure that the absolute worst harness example I can recall is in the very O/T Audi R8. The engine sections are as thick as your wrist and go up both sides of the car. Hand made, by the way. Embrace the simplicity of our ancient technology while we still have it!
    loudbang likes this.
  3. Mercedes had the worst wiring, it would crumble to your touch. Most of the Ford's I worked on used a ground type power system and multiple fuses for each circuit. GM's were not too bad until I had to rewire a 66 Chevelle that caught on fire.....1/2 year change in the wiring, I could not find the early one so I had to "cobble" the late one by changing the ends and wire coloring from the old one. The fire started because the owner had up in a clutch start switch and left the wires, and others loose under the dash to get caught by the pedal.
  4. ronzmtrwrx
    Joined: Sep 9, 2008
    Posts: 398


    That's funny right there.
    62rebel likes this.
  5. Blues4U
    Joined: Oct 1, 2015
    Posts: 3,525

    from So Cal

    :D :D
  6. LWEL9226
    Joined: Jul 7, 2012
    Posts: 241

    from So. Oregon

    Sometimes being colorblind can be an advantage, I do almost everything electrical with a meter or test light...

    Hnstray and wraymen like this.
  7. And without a diagram how do we know where it’s supposed to go? Without a correct pin out diagram how can you tell if it’s pinned wrong or production change

    One thing if you’ve designed the the system but without some good and correct input from the design team it’s hard to fix. I’ve seen plenty, but everyday still yet I fix something I have no knowledge of.
    Hnstray, 62rebel and VANDENPLAS like this.
  8. " I’ve seen plenty, but everyday still yet I fix something I have no knowledge of"

    A great candidate for the "quotes to live by" thread..
  9. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,324

    from illinois

    Kinda like , the older I get the more I realize how dumb I am ....
  10. I find a lot of the 50s and 60s factory service manual wiring diagrams somewhat lacking in detail when it comes to accessories like power windows, seats and sometimes wiper motor wiring. As has already been stated, sometimes there is a more detailed diagram in the component service section, but often there is just no information at all. Ford's 3 and 4 wire P/W motors are a good example, although I have found usable information in a Thunderbird manual that I should have been able to find in a manual for a lowly Ford.

    I worked for a time at an AMC dealership and the wiring diagrams in the manuals were full of misleading information, so yeah, I think it's pretty common.
    62rebel likes this.
  11. 62rebel
    Joined: Sep 1, 2008
    Posts: 2,327


    I wish there was a Bentley manual for the '63 Galaxie.... I had one (might still have it somewhere) for MG B and it had full color foldout diagrams for every mark (version) from '62 through '80. Photographs of the back of the dashboard, as well. Of course, it cost about eighty bucks even back in the '80's.....
    VANDENPLAS likes this.
  12. Yeah, I got burned on one of those once too... but I didn't remove the stubs from the connector and still had the old switch, so it wasn't a total disaster... LOL

    That taught me not to take anything for granted, haven't had 100% faith in a factory diagram since and it's paid dividends many times.
  13. The37Kid
    Joined: Apr 30, 2004
    Posts: 25,567


    Knowing less the more I read, Wiring diagrams are NOT the same as schematics is the latest tid bit. I understand dog shit with or without 32 different colored Crayons. There are no wires in yard work. Bob
  14. Diagrams (and there's more than one kind) and Schematics are two different things...

    A harness diagram will show where items/devices are located on the vehicle reasonably in scale, how the harness is routed to those items/devices, but usually has little or no individual wire/device info.

    A wiring diagram will show what harness wires go where and may or may not show where everything is in relation to everything else but will rarely have scale; most only give a general relationship. It will also usually lack some details, such as the inner workings of devices like some switches, relays, motors, etc. in the interests of drawing simplicity.

    A schematic will show an individual circuit or system in electrical detail, detailing individual wires/connections and usually including the inner works of devices, but won't show spacial relationships. If you're troubleshooting, this is almost always the best choice of drawings, but a lot of people have a hard time wrapping their head around the lack of spacial layout.

    To fully understand any electrical system (how it's installed and works), you really need all three drawings; harness, wiring, and schematic. Where the knowledge comes in is being able to interpret/integrate them into a working system. While it's possible to combine any/all of these onto one drawing, the drawing size gets unwieldy so quickly in order to retain detail/readability that it's just not practical. I personally wouldn't want to see anything more complicated than a mid-'50s car with minimal electrical accessories on anything smaller than 30" x 40" if combining the wiring/schematics. If adding the harness diagram, better bump it up to 3' x 6' to maintain legibility/scale. Start adding stuff like AC, power windows, air ride, etc, doubling or tripling the size over even that size would probably be needed.

    Years ago, I bought a mid '80s Taurus wagon with power everything, EFI, etc. I ordered the wiring diagram for it 'just in case'.... What showed up was a 9" x 12" manila envelope containing a couple of dozen individual sheets, each of which folded out into 30" squares. Four had 'match lines' on two sides, more had them on three sides, most had them on all sides. Not even I wanted to tackle this, I ended up throwing them away...

    With the small single or double page diagrams you find for most '50s/60s cars, we're lucky they're as good as they are...
    Last edited: Apr 12, 2019
    Hnstray and 31Vicky with a hemi like this.
  15. luckythirteenagogo
    Joined: Dec 28, 2012
    Posts: 1,219

    from Apex, NC

    Who ever converted my 50 to 12v did it the easy way, they just wired everything to the coil. I mean everything, the electric fuel pump, the blower motor, even the radio drew power from the coil.

    Sent from my SM-G960U using The H.A.M.B. mobile app
  16. X-cpe
    Joined: Mar 9, 2018
    Posts: 565


    A big box of colored pencils is your friend.
    62rebel likes this.
  17. 62rebel
    Joined: Sep 1, 2008
    Posts: 2,327


    Print out one as big as you can and use it for fixing the problem at hand using colored pencils or markers. Save it in case the problem pops up again. No need to fill in all the colors, just the applicable ones.
  18. We see these in 8.5 x11” or so,,,,
    It’s originally 36” x48” full Size blueprints.
    Be easy then right
    62rebel likes this.
  19. 62rebel
    Joined: Sep 1, 2008
    Posts: 2,327


    I print those out as high a magnification as my printer is capable and use them.
  20. tb33anda3rd
    Joined: Oct 8, 2010
    Posts: 14,812

    1. Connecticut HAMB'ers

    buy a parts is a wiring schematic actual size.
  21. Boneyard51
    Joined: Dec 10, 2017
    Posts: 2,081


    I had to deal with American LaFrance fire trucks for years. They had the worst electrical system on the planet! No two trucks were wired the same! Very generic diagrams/schematics, and the guy making the wire loom would just grab any color combination to finish the run. Many times I saw one color going into a loom the size of your arm and a different color coming out! Every circuit was supposed to be protected by fuses/circuit breakers, but more than once the firefighters had to leave the cab due to smoke off of burning wires!...... Earned my money on those trucks!

    loudbang likes this.
  22. If you break down a circuit diagram into systems, they are easier to understand and work out. Any system (ignition, brake lights, etc) starts at a power supply (usually a fuse), and ends at a load. If you follow a circuit diagram and draw the system out on a separate piece of paper, it will be easier to comprehend. The cars we goof around with have electrical systems which are 5% of a new-fangled auto's system. I'm glad I don't have to work on them anymore. Anything that has more than 3 wires going to the motor gives me the shits.
    TrailerTrashToo and Crazy Steve like this.
  23. Joe H
    Joined: Feb 10, 2008
    Posts: 734

    Joe H

  24. The37Kid
    Joined: Apr 30, 2004
    Posts: 25,567


    The thought of wiring just kills any reason to work on old cars, why have all those years go up in smoke. Bob

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