Need help with electrical!

[offrope33]

I am not a mechanic at all, i am just a 19 yo who started liking cars and likes building things, so bear with me if some terminology or methodology is wrong

 

Hello, I'm in a bit of a crisis with my car at the moment, and before I get told to do this, yes I have spent days searching the internet, and yes I have looked through the FSM for this model year of the 280z, and spent many days looking through the wiring diagrams trying to solve this problem.

 

A little backstory for this project of mine: My grandpa has had this car for about 30ish years now sitting on his property. I recently took an interest in the car and was starting to get into cars in general. So he decided to let me try to restore the car with him. I should mention the car had been stripped of all components for a full restoration that 30 years ago. so I started on the car approximately 2-3 months ago now, and am almost ready to start, and paint the car, and get it road ready.

 

Onto my electrical problems:  So after I got every electrical connection together through the entire car, we plugged in a new battery to start testing the electrical components. Right off the start there were issues but not too many, the engine would crank fine but we didn't have gas so we don't know if it would have started or not. but as i have been trying to solve the problems with the electrical, i accidently shorted a ground pin to the main headlight pin in a connection while light testing and since then, the headlights don't work, and the flashers don't work.

The fuses are fine none blown, and the fusible links are fine, they all get continuity & voltage through them. I have replaced the flasher relay and it didn't change anything, I have cleaned all the connections in the combination switch circuits.

 

Then when I was testing the ignition switch, I accidently cranked the engine, and my negative to chassis ground cable instantly melted.

Ever since then the positive terminal of my battery, has continuity to the chassis of the car, the engine and every single ground contact/cable throughout the car. Another thing, I'm not sure if this is normal or not, but in my fuse box, the left side of my fuel gage fuse (blue wire) has continuity with the positive terminal of my battery. 

 

Things i have tried to trace the problem so far: 

I have taken off all the important relays for operation and opened them, checked for any damage, and cleaned them.

I have been checking all my fuses and fusible links constantly to make sure its not them.

 

I did notice today, that when I unplug the fusible link in the picture, my positive terminal loses ground to the entire car, which has led me to believe its something to do with that cable.

 

Any help would be apprieciated 

 

[NewZed]

21 hours ago, offrope33 said:

after I got every electrical connection together through the entire car, we plugged in a new battery to start testing the electrical components. Right off the start there were issues but not too many, the engine would crank fine

 

21 hours ago, offrope33 said:

accidently shorted a ground pin to the main headlight pin in a connection while light testing and since then, the headlights don't work, and the flashers don't work.

The fuses are fine none blown, and the fusible links are fine, they all get continuity & voltage through them.

 

21 hours ago, offrope33 said:

when I was testing the ignition switch, I accidently cranked the engine, and my negative to chassis ground cable instantly melted.

Ever since then the positive terminal of my battery, has continuity to the chassis of the car, the engine and every single ground contact/cable throughout the car.

 

Fusible links can still show voltage and continuity even though they're melted.  A few strands of copper might survive.  If they've blown they'll be discolored and crunchy inside.  Take them off and see if the wire inside is intact.

 

It seems like you might have done the not uncommon thing of reversing your postive and negative cables.  Or you connected the negative cable to the wrong stud on the starter.  You caused a direct short when you actuated the starter solenoid.

 

The positive cable connects to the starter's copper solenoid stud.  The negative cable connects to the starter mounting bolt.  Don't assume that red is positive and black is negative.  Check the + and - on the battery and follow the cable to its correct position.

 

The fact that you are seeing continuity to ground on the positive cable might be because you fried the solenoid and it is shorted inside.  You can test that with your meter by disconnecting the cables and measuring resistance from the starter solenoid positive terminal to the starter body, where it mounts to the transmission.

 

Just some things to check.

[Sanchez]

I know your struggle of owning a Z as teen and the learning as you go process. I’m now in the process of a full chassis up rebuild and engine swap 11 years after getting mine as a 16yr old. The wiring on these cars always gets messy. My suggestion is get both the Haynes wiring diagram and FSM diagram and compare both when doing stuff on it. The Haynes sometimes has circuits for optional stuff, and depending on how you like to look at multi switch diagrams the Haynes or FSM might be easier to read for you. I second going through and replacing all the fuses and fusible links even if they look good. I’ve seen fuses look good but not have continuity, and fusible links test out fine but not function for the load on a particular circuit because they melted just enough.
If you have the money to spend now looking into the upgraded fuse boxes usual sold by Motorsport Auto is a good fire safety feature. Shorting across the old original hazard and flasher relays can kill them easily because they have shared circuits. take them out and bench test them, or just replace them with a modern Bosch style flasher relay. And check you multi switches for continuity too.