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hooked up a battery backwards

Discussion in 'The Garage' started by 86chevybanshee, Oct 22, 2004.

  1. 86chevybanshee

    86chevybanshee 1/2 ton status

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    my buddy has a 78 shortbed, the guy he bought it from put a black wire for the positive battery cable and a red cable for the negitve,my buddy put a new battery in it and hooked the - to the + and the + to the -, and smoke started coming from some where he sed, and now the truck gets no power at all, what could this screw up, the truck dosnt have a computer so it should be an easy fix right?
     
  2. diesel4me

    diesel4me 1 ton status Premium Member

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    Not really--he might have fried the diodes in the altenator,fusible links,and if your not lucky-- wires in the harness,and hope the radio wasnt on,or it will be toast too.This is why I always connect the cables to my battery when getting a jump--I know which is + and - regardless of the color on the cable(I've had black positive cables too!--but I usually paint them red,and the + terminal too).Hope it didnt wreck too many things--it might just be the fusible links if your lucky. /forums/images/graemlins/crazy.gif
     
  3. jakeslim

    jakeslim 1/2 ton status

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    the battery cables could both be green for what ever i care, always look at the battery itself to ensure a proper connection. I guess a person would need to know that its the negative wire going to the block.....
    .....a friend huh?.....ahhh yeah... /forums/images/graemlins/whistling.gif
     
  4. ntaj*ep

    ntaj*ep 1/2 ton status

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    Have him disconnect the alt. leads and see if it still "smokes" Assuming the truck is still equipt. with the internal regulator alt. he may have "smoked" the alt.
     
  5. 86chevybanshee

    86chevybanshee 1/2 ton status

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    yea someone else sed something about the fusible link thing, its that black tube looking thing on the red wire right?

    and yes it is my friends truck, the reason why i ask is because he wants to sell it to me now for $500
     
  6. diesel4me

    diesel4me 1 ton status Premium Member

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    There are 2 fusible links in the red wires at the starter solenoid,and another near the junction block by the brake booster in the red wire that powers everything in the cab--they look like wax or rubber cylinders on the wires--if they are burnt,buy new ones at the parts store and cut the old wires off just before the fuse links,and solder the new ones on.Hopefully it didnt fry too many things.I blew my 300 watt amplifier and a nice radio when I forgot to disconnect my battery in my van when I welded a repair panel on--didnt find out till I went to turn it on--sounded like a pig squealing,then that burnt transistor smell--I was pissed! /forums/images/graemlins/mad.gif /forums/images/graemlins/blush.gif /forums/images/graemlins/blush.gif
     
  7. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    For future reference.... The larger post on the battery is always positive and the hot lead runs to the starter, ground goes to the frame or alt. bracket. err....you should share that with your friend. /forums/images/graemlins/rotfl.gif
     
  8. 86chevybanshee

    86chevybanshee 1/2 ton status

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    the truck dosnt have one of those junction boxes
     
  9. 86chevybanshee

    86chevybanshee 1/2 ton status

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    what does the purple wire from the starter go to?
     
  10. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    My "friend" did the same thing once.....

    I .....uh I mean he /forums/images/graemlins/tongue.gif /forums/images/graemlins/blush.gif fried the ignition module in the distributor. The truck would turn over but not start. Luckily that was all I...uh I mean he did.

    Due to the short you created, it could have taken out many things. 1st recheck your ground and make sure it is making good contact. Check ALL your fuses with a multi-meter to make sure they are still intact. If that doesn't work, try a new (or spare) battery as that could have shorted. Disconnect the alternator. The truck should start (but not charge). You could have taken out the fusible link too. If it turns over without firing, then you fried the ignition module in the distributor.

    As for how "he" did it. Dark, raining, both cables the same color (don't ask), and he was in too much of a hurry........and it cost "him" more time and money than it would have cost to take 3 extra seconds to verify which wire went where.

    "He" was just a teenage them so "he" learned quickly that haste makes waste.
    /forums/images/graemlins/thumb.gif
     
  11. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Fusable links will not fry from hooking up the battery backwards.

    Hooking it up backwards won't make too much current flow through the wires.
     
  12. 86chevybanshee

    86chevybanshee 1/2 ton status

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    well i looked at it and the fusilbe links are melted. replaced the wires from the starter and spliced them into the harness,all the lights work, but nothing from the starter /forums/images/graemlins/confused.gif

    he gave me the truck for free because i told him it was completely screwed

    the frame and engine are 78 and the cab is an 86, i have the wiring harnes from my old 86, would that work instead of trying to rewire everything?
     
  13. diesel4me

    diesel4me 1 ton status Premium Member

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    Purple wire goes to "S" terminal on solenoid(the one nearest the engine,of course its the hardest one to reach if you need to jump it).It wont crank with that wire disconnected.It comes from the neutral safety switch and the ignition switch. The wiring harness on many GM trucks are very similar,but are different for EFI Vs carbed trucks--the computer trucks have tons more wires--but some of the harness is the same,might be easier than cutting and splicing the old wires.I wish I could get a free truck,so I could put my flatbed and crane back in operation--figures my tranny dies when scrap is 70 bucks a ton! /forums/images/graemlins/angryfire.gif /forums/images/graemlins/screwy.gif
     
  14. 86chevybanshee

    86chevybanshee 1/2 ton status

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    if i jump the solenoid, it should start right? what if jumping the solenoid donst work, does that mean the starter is dead?
     
  15. diesel4me

    diesel4me 1 ton status Premium Member

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    Yup--jumping it at the solenoid will tell you if its the starter or just a wire problem,but its a bitch to get at the "S"post on the solenoid--you'll probably end up getting a shower of sparks if you use a screwdriver,because it will ALWAYS hit the block or manifold instead of the "S" terminal like you want it too.You might be able to use a wire with an alligator clamp on it--clamp it on the "S" terminal and touch it to the + battery cable at the starter to jump it--if it cranks you have a problem in the purple wire,neutral safety switch,or ignition switch.You could run a bushbutton switch to the "S" terminal and a 12 volt hot wire instead of fixing it right--but it can be dangerous not having a neutral safety switch,especially if your not the only driver--dont ask me how I know this! /forums/images/graemlins/doah.gif
     
  16. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    ***
    Fusable links will not fry from hooking up the battery backwards.

    Hooking it up backwards won't make too much current flow through the wires
    ***

    I never said it will cause too much current. Actually the only way for too much current feed is to have a regulator go bad in the alternator. I'm assuming hooking up a battery backwards would create a large enough short to fry a fusible link from excessive heat (from resistance, not current). Apparently it did as he said the fusible links were melted.

    ***
    well i looked at it and the fusilbe links are melted
    ***

    It could have been something else (not ruling that out), but it seems as the only thing that caused it was reversing the polarity (bad for DC circuits).

    I'm by no means an expert on electronics, so I am open for debate with factual explanations.
     
  17. 86chevybanshee

    86chevybanshee 1/2 ton status

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    ok i jumped the starter, got it running, it only runs when the key is on the start position, would that purple neutral saftey switch wire have anything to do with it?
     
  18. diesel4me

    diesel4me 1 ton status Premium Member

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    You have to manually hold the ignition key in the "crank" position to make it run when you jump it???(you must have long arms!)-if thats the case the ignition switch might be fried in the "run" position,or perhaps the wire going to the coil from it is toasted or broken--check the fuses too,if its a computer controlled rig it might have a blown "ECM" or "IGN" fuse. Hooking a jumper from the HEI bat+ (big pink wire on the cap--disconnect it,hook a jumper lead where the pink wire went)and hook it to the battery + terminal(or the junction block near the brake booster,another convenient source of constant 12 volt power)and jump the solenoid--if it runs now,its not getting power to the pink HEI wire(a test light could be used to see if the pink wire has juice too,hook it from the pink wire to ground and turn on the key--if no juice check the fuses--hope its not the ignition switch,they can be a PITA to change.The purple wire only activates the solenoid to make it crank when you turn the key--its dead any other time.At least you can hear it run--thats half the battle won! /forums/images/graemlins/crazy.gif
     
  19. 86chevybanshee

    86chevybanshee 1/2 ton status

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    no its not computer controled, hmmm i think i might just give it back to him and say hes f***ed
     
  20. diesel4me

    diesel4me 1 ton status Premium Member

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    Or you could give it to me!--I'd rather fix burnt wires and chase electrical demons than put another tranny in my rotbox 74 GMC,and spend the rest of the winter replacing its rotted rotors,oilpan,frame,exhaust,and broken windsheild!.I'm debating whether its even worth pulling the 400 motor and flatbed/crane setup and plow frame off it before I scrap it--it'd be nice to find a similar truck to swap the parts into so I can make some dough junking the scrap in my yard before its price drops again.. /forums/images/graemlins/confused.gif
     

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