[Rhylor]

I had the car running yesterday, and had zero issues getting the engine to crank over. Today, when I tried to start it, the car wouldn't crank. With the key in the ignition, the battery meter reads about 12-14v, when turned to the on position the battery meter reads 0. Sometimes there are lights on the dash, and occasionally when I turn the key the car makes a loud bussing noise, or a solid click sound and voltage drops to 0. The weirdest part is that sometimes when I put the key in, regardless of its position, voltage on the gauge drops to 0. Additionally the door chime seems to be ringing at about 3x the normal speed.

I want to eliminate the ignition switch and starter as problems, so how would I go about doing that?

 

[steve240Z73]

Test your battery. I don't care if it's new. Load test it.

 

[Rhylor]

Test your battery. I don't care if it's new. Load test it.

got it tested at autozone, additionally, I've used three different batteries with the same result

 

[bonfire79]

download the FSM from xenonzcar.com for your year car. go through the electrical/ignition system troubleshooting sections and that should assist you in finding the correct diagnosis for the problem.

Bon

 

[Dave Datsun Tech.]

Check your battery cables, connections and grounds.

 

[steve240Z73]

So with the battery checked as good, the next suspect would be corrosion at the battery cables (as @Dave Datsun Tech. said, check the cables, the integrity of the cable & clamps, and the grounding points.) or at the fusible links. Sometimes the corrosion exists where the power feed splits apart to the fusible links.

Think of it like this:
The battery is like a water tower. You are measuring water pressure in the line (voltage), but there is a blockage in the pipe that just lets through a trickle of water (current flow). When you turn on anything, the water that was in the pipe downstream of the blockage flows out, but there isn't enough water passing the blockage, so the pressure drops (voltage gauge goes to zero).

Feel free to post photos of the fusible links, battery cables at the battery and grounds. Also ALWAYS post the year of your car when asking for help. You cannot receive specific guidance unless we know the year of the car and any possible modifications.

 

[Rhylor]

So with the battery checked as good, the next suspect would be corrosion at the battery cables (as @Dave Datsun Tech. said, check the cables, the integrity of the cable & clamps, and the grounding points.) or at the fusible links. Sometimes the corrosion exists where the power feed splits apart to the fusible links.

Think of it like this:
The battery is like a water tower. You are measuring water pressure in the line (voltage), but there is a blockage in the pipe that just lets through a trickle of water (current flow). When you turn on anything, the water that was in the pipe downstream of the blockage flows out, but there isn't enough water passing the blockage, so the pressure drops (voltage gauge goes to zero).

Feel free to post photos of the fusible links, battery cables at the battery and grounds. Also ALWAYS post the year of your car when asking for help. You cannot receive specific guidance unless we know the year of the car and any possible modifications.

That explanation definitely makes sense. The car is a 1981 280zx, sorry I didn't clarify that before. Ill have to take a look at the cables tomorrow, but today I ripped out the starter and bench tested it. Didn't seem to have any issues so I'm also ruling that out. How might I go about testing the fusible links? Thanks!

 

[steve240Z73]

For the fusible links:
First, inspect visibly. Remove them one at a time so you don't mix them up. Look for corrosion on the blocks and links. While the link is out, use an ohmmeter to make sure you have less than 1 ohm resistance across the link. (Hint: It should be pretty much 0.)
You may need to clean the links. I like using a wire brush on a dremel for the blocks. Sometimes you have to dip the links in vinegar to remove the corrosion. (After that, I like to dip the links in a solution of baking soda and water to neutralize the vinegar followed by a dip in denatured alcohol to remove the water. Blow with compressed air to evaporate the alcohol and use silicone grease on the links to reduce future corrosion.)

After you ensure the links are clean and secure, measure voltage to ground on both sides. They should both have the same voltage as the battery. A voltage drop can indicate corrosion or a bad connection.

Corrosion can also happen where the cable was split to go into the block. If that is the case, you probably want to find someone experienced with automotive wiring to address that problem.