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#1 Conner

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Posted 05 December 2017 - 02:13 PM

Background: 

When I got my 64 320 it hadn't run in many years and the battery was dead.  The battery cables were hooked up thus: 

 

Red cable--->Negative terminal on the battery--->Starter

Black cable--->Positive terminal--->Engine block

 

My impression this was a positive ground set-up. 

 

 

 

Last weekend I put a new battery in the truck because I'm finally ready to try to start it up.  Starter and generator have been rebuilt and re-installed (carburetor also). 

 

I connected the red battery cable, which is connected to the starter again, back to the negative terminal. 

When I tried to connect the black cable, which is again connected to the engine block behind the generator mounting bracket, I couldn't attach the black cable to the battery without some small sparks, hissing, and popping, almost like a dirty weld without the bright arc.  I disconnected the battery pretty quickly, afraid I was going to fry something. 

 

I should say I'm much more confident on the mechanical than the electrical aspects of these old trucks.  Also I'm suspicious of the truck's wiring because it has definitely been spliced in a few places. 

 

 

Anybody have any idea what my problem could be? 

 

Thanks. 

 



#2 Fetch

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Posted 05 December 2017 - 03:45 PM

Reads like you have a direct short or something is drawing power, headlights on, ignition switch in on position? First verify for your own information, check your generator tag, there should be a ground symbol in the lower right corner showing pos or neg ground. Hopefully, whoever rebuilt your gen checked for pos or neg ground.

 Process of elimination, disconnect the starter and reconnect the battery cables. If still arcing, start checking wiring for broken insulation, PO WIRING MODIFICATIONS, switch shorting, etc.

Its not a bad idea to check and clean all ground straps and clean electrical connections. They will corrode over time and loose contact. I presume you have the wiring diagrams.



#3 wayno

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Posted 05 December 2017 - 06:34 PM

Is this the way your generator is wired?

DSCN7477.jpg

If it is wired like the photo above then disconnect the wires from it and see if you can connect the battery.


 

 


#4 Conner

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Posted 07 December 2017 - 07:18 AM

Thanks to both of you for the advice. 

I will check the generator wiring and try disconnecting that and the starter to see what I get and report back. 

I do have a wiring diagram. 

Thanks. 



#5 difrangia

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Posted 07 December 2017 - 03:10 PM

This is the one that I use; has wire colors labeled if you can read them. Has most of the optional accessories included. Our truk is changed to negative ground and changed to alternator but works good for running down the circuits.

 

Wiring_Diagram.jpg


Better to have a bottle in front of me than a frontal lobotomy !!


#6 Conner

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Posted 26 December 2017 - 11:34 AM

Thanks everyone.  

I got some time today to try to diagnose this problem.  

It looks like my generator is hooked up the same as yours, Wayne.  

 

gen_wiring.JPG

 

The top-most connection is the red/white striped wire.  The bottom-left is a white/black striped wire.  The bottom-right is actually two black wires.  Also coming out of the harness there is a yellow wire you can see resting on the generator above.  Where should that connect?  

 

So I disconnected all three generator wires and made sure they weren't touching anything.  Then I tried to connect the battery.  No luck.  Same popping and sparking.  

 

Question:  the black wire grounds to engine block at the generator mount.  Is that it or is there then a ground cable that connects the engine somewhere to the frame?  If so, where should I look for that to make sure it is intact?  

 

Any suggestions?  

 

Thanks.  



#7 Conner

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Posted 26 December 2017 - 12:03 PM

More information.  
Starter is grounded to the frame.  With the generator still disconnected I swapped the battery around and tried to connect it negative-ground style, and still the same sparks from the battery.  



#8 wayno

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Posted 26 December 2017 - 12:06 PM

The yellow wire goes to the water temp sender.

 

The starter does not ground to the frame.


 

 


#9 wayno

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Posted 26 December 2017 - 12:17 PM

OK, the negative cable on the battery goes to the starter relay, the other side of the relay goes to the starter, nothing else connects to the starter post.

The positive cable on the battery goes to the engine block, mine connects right next to the thermostat housing but mounted to one of the generator mount brackets would likely also work.

The negative cable that connects to the starter relay also has a large white wire and a smaller white wire with a red line connected on that side of the relay also, no other wire other than them 3 wires are on that side, the other side of the relay has no wires other than the cable going to the starter.


 

 


#10 wayno

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Posted 26 December 2017 - 12:32 PM

OK, I looked all around and could not find any strap going from the block to the frame on my positive ground 1963 L320, but there are 3 black wires connected to the starter relay mount screw, I suspect that at least one of them wires is one of the black wires connected to the generator housing.

You need to forget about how there are lots of grounds on negative ground systems, it doesn't work that way on positive ground systems, it is very confusing.

It took me a few tries to get my positive ground electronic ignition working, it was crazy to me how they wired it and it didn't make sense, but when I followed the diagram wire for wire it worked, what is really crazy is how one is supposed to wire a Smiths electronic tach in, I have one but have not wired it in yet.


 

 


#11 wayno

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Posted 26 December 2017 - 12:52 PM

See the 2 white wires connected to the post with the negative cable coming from the battery, also see the black wires connected to the relay mount screw.

DSCN7597.jpg

Do you see the yellow wire connected to the temp sender, also see the main positive cable connected to the block.

DSCN7598.jpg

Another photo on the generator wiring.

DSCN7599.jpg

See the negative cable coming from the relay going to the starter, the starter only has the cable going to it, no other cable is connected to that post.

DSCN7605.jpg

I could find no other main cable going from the block to the frame.


 

 


#12 Conner

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Posted 27 December 2017 - 06:47 AM

Thanks for taking the time to post all those pictures, Wayne.  They are very helpful.  

 

Looks like I'm going to need to spend some quality time with my wiring diagram tracing wires to figure this out.  

 

Just FYI my starter has a ground cable to the frame.  It is located about 180 degrees opposite where the battery cable bolts to the starter--on the underside. 

 

You can kind of see it from this picture, which was taken from underneath the truck looking up and back toward the starter (you can see the oil pan in the foreground).  The ground cable is mounted to the shiny bolt and snakes up and to the left to the frame.  

 

2015_07_05_starter%20reinstall%20(14).JP



#13 wayno

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Posted 27 December 2017 - 10:56 AM

OK, mine has that ground cable also, I just could not see it.

Calling it a ground cable is what confuses people, they think ground and that gets one back to traditional thinking, ground is negative and that is a minis, positive is a plus.

When you had these components rebuilt(starter/generator) did you remove any wires from anything other than the components? 
Did wire/rewire anything?


 

 


#14 Conner

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Posted 27 December 2017 - 01:22 PM

No I just removed the bolts and wires connecting the starter and gen to the truck and then when I reinstalled them I did my best to return them to the way they were (took lots of pics before disassembly).  But I will say that the condition of the truck when I got it was unknown and probably not stock, since it was a partial restoration that was many years old from the 90s.  

 

I don't know if the rebuilder may have reversed polarity either intentionally or otherwise.  That's another variable.  

 

Thanks.  



#15 wayno

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Posted 27 December 2017 - 02:12 PM

So take the starter cable off the starter although I just don't see that being an issue unless the key were in the start position, maybe the relay/solenoid is stuck on or being energized when the cable is connected to the battery.

When you took the wires off the generator that took it out of the loop, is anything else on, headlights, the ignition(key), is there an aftermarket radio installed, brake light on?

Pull all the fuses, better yet first remove the white wires from the negative cable side of the starter relay/solenoid, that will take all the wiring out of the loop, connect the battery as positive ground and start testing with them 2 main wires, the white and red line one goes to the fuse box, the white one goes straight to the generator, find out which one throws sparks, if it sparks without them 2 white wires connected there is a direct short somewhere, the positive side of the battery goes only to the block, no where else, just that one cable, the negative side of the battery goes to the starter relay post closest to the battery, that cable only goes to that post, no where else, that is where the 2 white wires are also.

Did the former owner say it was still positive ground?


 

 


#16 Stoffregen Motorsports

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Posted 28 December 2017 - 10:02 AM

There should always be a ground from the frame to the engine block (or transmission case). A heavy gauge (8-10ga) ground should be present at the body too.



#17 Charlie69

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Posted 28 December 2017 - 02:48 PM

I am curious and it has been decades since I worke on a positive ground. First I would call the shop that rebuilt the generator and starter to verify if they are wired for positive ground.



#18 wayno

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Posted 28 December 2017 - 04:38 PM

I am curious and it has been decades since I worke on a positive ground. First I would call the shop that rebuilt the generator and starter to verify if they are wired for positive ground.

He completely removed the wires from the generator and it still threw sparks Charlie, and the starter is kinda isolated unless the relay/solenoid is activated, so as long as the relay/solenoid is wired properly and functions properly the starter doesn't play any role in this issue.

These positive ground trucks have quirks, like you can only use a positive ground radio unless the radio and antenna are completely isolated from the truck as the antenna screws everything up as it is a dedicated positive ground antenna, it cannot be changed same as the matchbox distributor, the distributor housing is a dedicated negative ground, it cannot be changed as the distributor has to mount into the block, so it can only be used on negative ground systems.

I suspect something else is wired negative ground and that has to be found or something else has already shorted out/melted from the battery cables being put on backwards and that will have to be figured out also, my guess is something is/was wired wrong, one has to separate each circuit until it is figured out which circuit is the issue.

I would start with them 2 large white wires on the battery side of the relay/solenoid, the larger one goes to the regulator, I would test that one first, remove it along with the other white wire and then connect the battery cables, test touch it to where it mounts, if no big sparks that is not it, the other goes to the fuse block, test touch it and sparks remove the fuses, test touch again if it still sparks it is one of the wires between the relay and the fuse block, if no spark mount the wires back onto the relay and figure out which fuse circuit is the issue, I don't believe he will get that far as it should have blown the fuse when he connected the cables to the battery.

Also the fuse block should be inspected closely, if anything is grounding this will be an issue. 


 

 


#19 Conner

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Posted 28 January 2018 - 08:52 AM

Thanks everyone for your input on this.  It's been very helpful.  

 

I finally got day on the the weekend that wasn't arctic conditions yesterday to try some of Wayne's suggestions.  

 

Generator was still disconnected, still had the sparks when trying to connect the battery cables to the battery.  

 

So I disconnected the battery cable from the starter.  Bingo!  No sparking when trying to connect the battery. 

 

I re-connected the generator and still good--no sparks when connecting battery cables to the battery. 

 

However, with the battery connected I got nothing.  Headlights don't work, tail lights don't light when pushing the brake pedal, turn singles, horn--nothing.  

 

 

Any help would be appreciated.  

 

How to best chase down why the electrical system isn't working with the battery attached (and without the starter)?  

 

Also, any ideas on what is the starter's problem?  It was rebuilt.  

 

Thanks again!  



#20 wayno

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Posted 28 January 2018 - 09:01 AM

Can you get a photo of the starter relay and where the wires are connected on it.

It should not matter how the starter is internally wired as it is not in the circuit until the key is turned to the start position, something is externally wired wrong, since that is the first place the starter cable goes lets start there.