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Under hood wiring - Part 1

Discussion in 'Electrical & Audio' started by Scott91370, Feb 8, 2020.

  1. Scott91370

    Scott91370 Full Access Member

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    Trying to get the truck running this weekend (no spark) but I have several wires that I don't know where they go and I'm having a hard time with the wiring diagrams I have found. Basically they're not dumb enough for me to follow.
    First problem is; on the driver's side there is a wiring block that comes through the cab. I have 3 wires that go nowhere from this block, here is a pic:

    Pink - connector:
    Green - connector:
    Brown - cut, no connector



    Second issue I have this on the passenger's side. This pink wire was connected to the coil on the distributor (I think it may be the wrong one since I was not getting spark). As well as all the other wires in this picture, none of them were connected.

    Third issue is another green unknown wire that comes off what I think i the oil pressure sending unit wiring harness:
     
    Last edited: Feb 8, 2020
  2. 82sbshortbed

    82sbshortbed Supporting Member Supporting Member

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    I can't see your pics but, if you run a hot wire with key on to the post on distributor that says bat then you should get spark.

    If not then at least you've got a direction to go from there.
     
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  3. Scott91370

    Scott91370 Full Access Member

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    That worked!
    Did that and no spark. Neighbor and friend came over and we traced it to the little black module in the distributor. Swapped it and we had spark. Found TDC for #1, out everything back together and BAM! No spark, again. Not sure what it is now, have a feeling the same module went out but wouldn't have a clue why.

    I wonder why the pics don't work. I uploaded them to the site then added them to the post. Hopefully it is only the way you're connected and everyone else can see them.
     
  4. Termite_Delight

    Termite_Delight Full Access Member

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    I can't see them either.
     
  5. chengny

    chengny Full Access Member

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    Without images it's hard to visualize what you are dealing with. But just in general:

    There are two PNK leads coming through the bulkhead connector.

    One is power from the ignition switch to the B+ terminal on the ignition coil. That wire transits the connector at the 2nd row from the top/3rd bay from the right.

    The other PNK wire is power to the windshield washer pump. It transits the connector at the top row/3rd bay from the right.

    GRN lead. There's only one out of the bulkhead connector. It is the sensing leg for the coolant temperature gauge and connects to the temperature sender (which is screwed into the LH cylinder head between 1 & 3 cylinders). Transits at 3rd row down/1st bay on the right.

    BRN lead. It transits the connector block 4th row down/1st bay on the right. It goes to the # 1 terminal on the alternator. In the cab it connects to the alternator warning light or the ignition switch - depending on whether or not you have gauges.

    The second PNK wire coming over from the passengers side may well be the power supply to the WSW pump as discussed above.

    As far as the other GRN wire; are you sure it isn't the other end of the coolant temp sensing leg? Except for the power to the horns, there are no other GRN leads in the engine compartment - and the GRN to the horns transits the connector block in the forward light section.

    Click on the image to enlarge:

    [​IMG]
     
    Last edited: Feb 8, 2020
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  6. eskimomann209

    eskimomann209 Full Access Member

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    Can’t see them
     
  7. Scott91370

    Scott91370 Full Access Member

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    Let's see if this works:

    First problem is; on the driver's side there is a wiring block that comes through the cab. I have 1 brown wire with no connector on the end that goes nowhere from this block - labeled unknown at the bottom right of the picture. It's not the alternator wire, that one is connected.
    [​IMG]
    Green is coolant temperature gauge and connects to the temperature sender (which is screwed into the LH cylinder head between 1 & 3 cylinders).


    Second issue I have this on the passenger's side. This pink wire was connected to the coil on the distributor (which we now know is the wrong one since I was not getting spark). As well as all the other wires in this picture, none of them were connected.
    [​IMG]



    Third issue is another greenish blue unknown wire that comes off what I think i the oil pressure sending unit wiring harness (not the bulkhead connector):
    [​IMG]

    Comes from above plug/harness to this end connector: Electric Choke?
    [​IMG]


    Last issue, for this thread, Green Connector:
    This connector is in the same harness as the A/C plug. Fast Idle Solenoid?
    [​IMG]
     
    Last edited: Feb 9, 2020
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  8. Scott91370

    Scott91370 Full Access Member

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    I have now found another connector with a blue wire and yellow wire.
    It comes from loom under the truck, driver's side.
    Blue Yellow Connector.jpg
    Blue Yellow in loom.jpg
     
    Last edited: Feb 9, 2020
  9. chengny

    chengny Full Access Member

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    That plugs into the EGR bleed solenoid - part of the TCC control circuit.
     
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  10. Scott91370

    Scott91370 Full Access Member

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    Thanks. I see nothing else EGR looking on the truck so I will find a nice place to tuck it away.
     
  11. Matt69olds

    Matt69olds Full Access Member

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    274902A2-11DB-45F6-9563-E6FACA834568.png This wire went to the choke heater on the passenger side of the carburetor
     
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  12. Matt69olds

    Matt69olds Full Access Member

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    My first thought for this wire was for the temp sending unit, but you said it was part of the A/C harness. That suggests to me your on the right track thinking idle solenoid. The blue wire you mentioned is most likely the oil pressure sending unit. Make a jumper wire with the smallest rating fuse you can find. With the key on, ground the blue wire. The oil gauge should drop to zero, or the light come on. Same thing with the green wire. If the gauge goes full hot (or the light comes on) then you know what that wire does.

    the 4 pin connector most likely went to the distributor. If your distributor does t have a matching plug, then someone sometime in the past “lobotimized” your truck by removing the computer controlled distributor and replaced it with a old school HEI.

    A65C46E8-5E52-401F-96DD-1586860F7AFA.jpeg
     
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  13. Scott91370

    Scott91370 Full Access Member

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    Thanks everyone for all the input! That is all but the one, what appears to be, brown or tan colored wire that the connector was clipped from which could be the alternator gauge wire
    that chengny mentioned:
    I just don't remember a #1 marked terminal on my alternator and it's raining so much today I won't be able to double check.
     
  14. MikeB

    MikeB Full Access Member

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  15. Scott91370

    Scott91370 Full Access Member

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    I like that!

    I think I now have everything sorted. I think the one I call brown is actually tan and it is for electric choke.
    Well, except maybe this group which we think was for the old distributor:
    [​IMG]



    Thanks to everyone for your help!!
     

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