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Help! Electrical problem. (Battery, alternator, starter, relay?)

Discussion in 'The Garage' started by Cntymnty77, Mar 13, 2017.

  1. CK10

    CK10 1/2 ton status Premium Member

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    If you can get ahold of one I'll be glad to help you do some troubleshooting. Your local auto parts store can charge/test your battery for you for free as well so we can get reliable baseline numbers when we get down to testing.

    If you can't find a meter to borrow don't feel like you need to spend a ton of money on a Fluke or other pricy meter, if you find one that tests resistance (ohms) and voltage it will do most of the things you ever want need it to do. You'll really learn to like it when you get deeper into fixing the PO wiring hacks later on.
     
    Last edited: Mar 20, 2017
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  2. Cntymnty77

    Cntymnty77 1/2 ton status Premium Member

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    Thanks for the help!

    Does anyone have a wiring diagram for these trucks that are easier to read? I have the ones that have all the lines and symbols on them but those suck and I can't tell what half of that crap is.
     
  3. superbuickguy

    superbuickguy 1/2 ton status Premium Member

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    check your positive lead at the starter. you issue sounds like either that is failing or the starter solenoid (small thing on top of the starter) has failed. when you said it cranked slower and slower that is not a fuse failing... that's a bad connection.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    "Easier"? Easy is having the right year manual and learning how to read them. Far better than any generic alternatives you might get, like the ones in the back of the Haynes. http://67-72chevytrucks.com/vboard/showpost.php?p=5621043&postcount=1
     
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  5. Cntymnty77

    Cntymnty77 1/2 ton status Premium Member

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    Good point. I can read any kind of drawing, schematic, prints, etc., other than electrical. I've gotten better but for some reason the electrical diagram jack with me. Thanks for the help.
     
  6. Cntymnty77

    Cntymnty77 1/2 ton status Premium Member

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    Figured it out! I decided to use the jumper cable trick and it worked. I jumped between the positive battery terminal and the junction box on the fire wall to see if I could get power. I made the connection, turned the key and I got power and it turned over. I disconnected the jump and started inspecting the positive lead from the battery to the junction box. I found no wear, connection pull-outs or a bad fuseable link (those don't exist on this anymore). The only thing left was the 30A fuse a PO had installed right off of the battery. I looked at that previously but I guess I didn't look at it hard enough. It was smoked. Went up to O'riely's, got a new fuse and it started right up!

    IMG_4820.JPG
     
  7. superbuickguy

    superbuickguy 1/2 ton status Premium Member

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    don't ask me how much I hate those fuses.... I cooked an alternator because of one that corroded.
     
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  8. Cntymnty77

    Cntymnty77 1/2 ton status Premium Member

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    I'd like to get rid of this set up when I rewire it.
     
  9. CK10

    CK10 1/2 ton status Premium Member

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    Good find, you'll have plenty more surprises when you dig into it. At least the PO protected the circuit in some way, don't want truck fires!
     
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  10. diesel4me

    diesel4me 1 ton status Premium Member

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    You can buy replacement fusible links--I'd put one in place of that fuse..just imagine getting onto a busy interstate,and you punch it to merge into traffic,and that 30 amp fuse decides to blow---and your truck stalls...:yikes:..

    Fuses don't handle temporary overloads,they just pop--a fusible link will fry slower,at least give you a chance to pull over if something shorts out--yet still prevents the harness from going up in smoke completely..
     
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  11. superbuickguy

    superbuickguy 1/2 ton status Premium Member

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    fusible links - I can assure you that they blow instantly too.
     
  12. diesel4me

    diesel4me 1 ton status Premium Member

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    Yes,IF they are subjected to a severe dead short...no argument there,that is why they put them there...but a fuse could pop due to a sudden voltage surge or demand for high current (like turning the high beams on at night for instance)...

    Most newer vehicles that use fuses instead of fusible links have ones rated at much higher amps,at least 50 amps,I have seen a few 100 amp ones even..they have to be able to withstand the maximum amps the alternator can make..
     
  13. superbuickguy

    superbuickguy 1/2 ton status Premium Member

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    I-84 eastbound, 60 mph just after Multnomah Falls in Oregon, 4 am on a winter, raining night.... yeah, I know all about going from light, music and speed to utter darkness and silence. Angels were certainly watching over me - where it happened was enough of a shoulder that I could pull off the road without blocking any traffic 100 yards in either direction and I would have been blocking traffic. If I had been blocking, they never would have seen me in time. The failure threw me off because I figured that with 2 fusible links that you'd either lose dash power or alternator power (so I went and got a new starter thinking that was the issue - the power terminal)... I wasn't right - it blew both links and never gave any warning. I had put a transmission in and barely caught the wire between the bellhousing and the engine block - it wore for about 1000 miles then dead shorted.

    I run the reset-able main fuses now - though I need to even put a warning there - they can partially reset, letting some power through by not all (I went, "well, I'll be a monkey's uncle" when I figured that out - well, maybe I didn't use the words uncle or monkey, but you get the idea)
     
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  14. diesel4me

    diesel4me 1 ton status Premium Member

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    I had a '71 GMC that had a later 305 in it when I got it --whoever did it used the HEI distributor and decided to hook its power source to the wire that went to the original points coil--truck always had a annoying hesitation off idle,and felt like it wasn't making full power at full throttle..I even rebuilt the carb assuming the accelerator pump was going bad..didn't help..

    One night I was coming home from work in the dead of winter--was pitch black by 5 pm,and as I went to throttle it up to get on a highway ramp,it suddenly stalled,and refused to re-start..it acted like it ran out of gas--sputtered and coughed and almost sounded like it was going to recover,but it stalled...

    It was about 30 degrees and not very pleasant outside--I did some hasty diagnosis and soon learned it had no spark..

    While I was sitting in the truck to get warm again,I decided to turn on the radio--and for the hell of it,tried to crank it over--and it started!..
    I drove it home with no stalling,and it made it to work the next day,however,when I left for lunch and headed for a burger joint up the road a mile or so,about half way there it started to stall,but just before it died,it "caught" and ran normally again...

    When I went to leave ,the truck refuses to start again...
    I get out and pull off a plug wire,and put it on the air filter housing--good thing I have long arms,I was able to reach the key and crank it over while watching for spark...the dam thing started up on 7 cylinders!..I just hopped in it and drove back to work..
    I got it started and made it home after work OK..

    I decided to take my K5 to work the next day!...

    When I got home I started looking around for whatever might be causing the stalling issues,I found the old coil wire had been spliced into the HEI cap--I knew that was not the right way to wire it up,so I got some 10 ga, wire and ran it right to the fuse box to a empty tab that only got power with the key "on" and while cranking--it solved the stalling issue and the hesitation!..

    I had noticed though,every time it was about to stall,my dash lights and headlights would start dimming and brighten back up--thinking maybe the headlight wiring may also be fudged,I inspected it from the light switch to the lamps,and found nothing unusual in the wiring-.

    What I did find was someone had substituted two of the circuit breaker type things that will plug into a fuse box,both rated 20 amps..one was for the "IGN" fuse!...the other was for the "PNL" lights (dash cluster)...evidently those things are activated by temperature and "re-set" themselves after cooling off awhile..

    Further inspection found some wiring from the fuse box to the courtesy lamps had been smashed under the rug by my size 12's and also were pinched in the door sill trim plate--fixed that and put fuses back in of correct amp rating,and had no more problems!..:screwy:..
     
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  15. superbuickguy

    superbuickguy 1/2 ton status Premium Member

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    amazing how well these things work once the ghost of Bubba has been excised.
     
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