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Wiring questions...

Discussion in 'The Garage' started by Confedneck79K30, Jan 31, 2007.

  1. Confedneck79K30

    Confedneck79K30 3/4 ton status

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    ok, so looking at the wiring harness from my alternator, and there's a wire off the back that has a fuse/fusible link near the alternator, with 2 wires coming off the fusible link, one runs into the harness, and one that comes out and has a female spade connector on it, where the heck does it go?

    also, can someone show me a diagram of how the starter should be properly wired to the junction block on the firewall and where all the wires to the junction panel go to or come from??

    tia!!

    'fed'
     
  2. longbedder

    longbedder 1/2 ton status Premium Member

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    Year/model of vehicle and engine type are needed to answer your questions fully.

    There is a purple 12ga wire coming out of your firewall harness. Check it with a meter so that it's only hot when the key is held in the "start" position. This goes directly to the small post marked "S" on your starter solenoid. This post is also the closest to the engine block.

    I'm guessing you're talking about the largest single wire coming off the alternator (attached via a hex nut to the back of the alt). That's the juice coming from the alternator. Just attach it to the + side of your battery. The factory did this indirectly (attached it to the large battery cable at the starter end), but it'll work just fine if you attach it directly to the batt.

    If you want to clean it up some, cut and get rid of the brown wire coming out of the aternator. It's only purpose is to light an idiot light if your alternator dies (and works maybe half the time). You're better off watching your voltage gage. Then, just cut the red lead coming out of the plastic harness to about 4" long and attach it to the hex nut stud on the back of the alt I talked about earlier. That way you've got only one wire going to/from your alternator with the same functionality (aside form the dubious idiot light).
     
  3. longbedder

    longbedder 1/2 ton status Premium Member

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    Like this...

    alternator.jpg
     
  4. Confedneck79K30

    Confedneck79K30 3/4 ton status

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    ok well its a 77/79/86 chevy k30 with a 350/465 and not one brown wire on the alternator, ill try and get a pic tomorrow if its not dark again...

    none of my gauges currently work, its all part of the project
     
  5. Confedneck79K30

    Confedneck79K30 3/4 ton status

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    also, where should the oil pressure sender and coolant temp sender be on the block/engine? i think oil pressure is on the drivers side, middle block, mid height? if so, it reads 30-40 psi with the truck off, and over 60, running... maybe i should just buy all new sensors and gauges, eh?
     
  6. longbedder

    longbedder 1/2 ton status Premium Member

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    Oil pressure is tapped in at the top rear driver's side of the engine block (ery rear of the lifter valley). Either there's a tube that goes from there into the cab (mechanical oil pressure gauge) or a small canister with a wire attached to it (electrical oil pressure gauge).

    Engine temp is tapped into the cylinder head near an exhast port or right near/on the water neck in the intake manifold.

    The factory gauges almost never work on a GM truck that old, and if they work they're usually not accurate (except the voltmeter is usually OK). It seems like I remember some company that would fix and recalibrate them, but I'd just get some aftermarket ones. With some fab work, you could have a pretty cool looking dash that has very accurate AutoMeter gauges or something. If you're just wanting something cheap that works, get a 3-gauge cluster kit from Autozone or Summit.
     
  7. diesel4me

    diesel4me 1 ton status Premium Member

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    that works,BUT...

    Hooking it up like that "full feilds" the altenator!..it will overcharge if wired that way..that brown wire and the "ALT" light are what energize the field coil inside the altenator,and the bulb gives the correct resistance to the field coil, so it wont overcharge..you could use a resistor between the stud terminal and the "F" terminal where the brown wire was to make it charge correctly..

    If you don't believe me,look up "Weldanator" on google,and find the schematic--you'll see they tell you to wire up the alternator like yours is pictured to get maximum voltage and amperage--only they ground out the regulator, so its completely unregulated,and it can deliver 15-150 volts!..yours with the regulator in the curcuit wired as you have it pictured is probably putting out 15+ volts constantly...not the best thing for your battery and possibly bulbs and other items ..:crazy:
     
  8. Confedneck79K30

    Confedneck79K30 3/4 ton status

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    ok so i bought a oil pressure sensor and coolant temp sensor and a cheapo 3 gauge pod today... gonna wire it tomorrow...
     

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