Jump to content
Sign in to follow this  
Conner

Snap, Crackle, Pop

Recommended Posts

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. 

 

  • Like 1

Share this post


Link to post

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.

  • Like 1

Share this post


Link to post

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.

  • Like 2

Share this post


Link to post

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. 

  • Like 1

Share this post


Link to post

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

  • Like 1

Share this post


Link to post

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.  

  • Like 1

Share this post


Link to post

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.  

  • Like 1

Share this post


Link to post

The yellow wire goes to the water temp sender.

 

The starter does not ground to the frame.

  • Like 1

Share this post


Link to post

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.

  • Like 1

Share this post


Link to post

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.

  • Like 1

Share this post


Link to post

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.

  • Like 1

Share this post


Link to post

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

  • Like 1

Share this post


Link to post

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?

  • Like 1

Share this post


Link to post

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.  

  • Like 1

Share this post


Link to post

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?

  • Like 1

Share this post


Link to post

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.

  • Like 1

Share this post


Link to post

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.

Share this post


Link to post

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. 

  • Like 1

Share this post


Link to post

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!  

  • Like 1

Share this post


Link to post

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. 

  • Like 1

Share this post


Link to post

Here are some pics of what I've got, wiring-wise.  Unfortunately some of the harness and individual wires have overspray on them, so it isn't the clearest what is going where.  

 

I also noticed that a bunch of the wires that go to the front headlights are just wrapped up and tucked in behind the grill and don't connect to anything, so I guess I shouldn't be surprised that the headlights are working.  

 

IMG_2020.JPG

 

IMG_2021.JPG

 

IMG_2022.JPG

 

IMG_2023.JPG

  • Like 1

Share this post


Link to post

Our 320 has the wiring for the fog lights though I don't believe it ever had the lights. The wires were, kinda like you described, just doubled back and taped into the loomin the front header area. I'd have to refer to a printed copy of the colour marked wiring diagram that I have out in the shop, but the copy I have on my computer looks to have a black and a red/green wire for the fog lights. Maybe they were pretty much all wired for at least some of the options so that if a potential buyer wanted something dealer added, it would be pre-wired and all the dealer would have to do was bolt on the hardware and locate the wiring and hook it up ?? 

 

Man, that is some crummy looking wiring in the photos. The actual loom looks not so bad, just dirty/corroded as hell. I believe that I'd start by doing a real good cleaning of all the electrical terminals starting with the fuse box. I've experienced a situation where I lost all external lighting. I traced it down to a crummy fuse contact on the fuse box. Cleaned all the terminals and 'No more  problemo'.

  • Like 1

Share this post


Link to post

Where is this starter relay, here is mine, it has the negative battery cable going to it(mine is positive ground), and the other main cable goes to the starter.

DSCN7597.jpg

  • Like 1

Share this post


Link to post

You can use some acetone or lacquer thinner on a rag in a well ventilated area to clean over spray off of the wires and loom.  Both of these liquids are highly flamable so please disconect the battery and remove it for better access to the wiring.

 

I totally agree with difrangia on the cleaning of all the terminals and devices (fusebox, etc.) as this is the major cause on these old Datsun's wiring problems.

Share this post


Link to post

Where is this starter relay, here is mine, it has the negative battery cable going to it(mine is positive ground), and the other main cable goes to the starter.

 

 

 

I don't have anything that looks like that in my engine bay.  I guess it's missing.  When I got the truck the negative battery cable went directly to the starter and the positive to the engine block.  The only other wire from the battery splits off the negative and runs over to the voltage regulator--it is the yellow wire connecting to the top left of the voltage regulator in the first picture in Post #21 above.  

 

 

Progress!  I pulled the starter and removed all the connections and re-connected the wires and re-installed it.  I also cleaned up the ground cable going from the underside of the starter to the frame.  

 

Now I have no trouble connecting the battery.  No more sparks.  

 

However, I still don't have any power to anything in the truck with the battery installed.  When I turn the key I get nothing, and no lights in the cab or headlights work.  

  • Like 1

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×

Important Information

By using this site, you agree to our Terms of Use.