No Spark issue. Negative voltage on ignition switch.

[280zdude]

So new news I just connected the negative terminal to the the red probe and the black prob to the body and got negative 12 volts but when I did it the other way I got nothing.

[280zdude]

2 minutes ago, Zed Head said:

Yep, your battery cables are backward.  Hopefully nothing has been damaged.  

The cable that your finger is pointing to should connect to the - post on the battery.  Negative.  Ignore any cable or wire colors around the battery.  Red and black are meaningless.

 

I see can anyone send me a pic of how the smaller cables are connected. Hopefully I bought the car like this there were a couple blown fuses but only for the lights and what not. Hopefully not wires have been shorted in between 

[Zed Head]

Making progress.  The backward battery is one of those Nissan pitfalls that catches many people.  Before you reconnect the battery though, check the two small wires that feed the EFI system.  You might have got lucky and those were switched also, meaning that they are now right.  You don't want to connect your EFI system backward.

[280zdude]

4 minutes ago, Zed Head said:

Making progress.  The backward battery is one of those Nissan pitfalls that catches many people.  Before you reconnect the battery though, check the two small wires that feed the EFI system.  You might have got lucky and those were switched also, meaning that they are now right.  You don't want to connect your EFI system backward.

How would I check those? 

[Zed Head]

1 hour ago, 280zdude said:

I see can anyone send me a pic of how the smaller cables are connected. Hopefully I bought the car like this there were a couple blown fuses but only for the lights and what not. Hopefully not wires have been shorted in between 

You'll want to use your meter and determine which of the small wires is connected to ground and which is connected to the power supply to the EFI system.

Might be a good time to study a wiring diagram.  Doesn't look like you're one of the lucky ones with a complete car that just needs a couple of small things.  You can't get very far on the 280Z's without building up some good electrical skills.  It will be fun!

 

 

 

Edited December 23, 2020 by Zed Head

[280zdude]

1 minute ago, Zed Head said:

You'll want to use your meter and determine which of the small wires is connected to ground and which is connected to the power supply to the EFI system.

Might be a good time to study a wiring diagram.  Doesn't look like you're one of the lucky ones with a complete car that just needs a couple of small things.  You can't get very far on the 280Z's without building up some good electrical skills.  It will be fun!

 

 

 

Yup that’s the diagram I’ve been using to check the wires. Let’s see I’m trying to tackle one thing at a time first spark then fuel. Any suggestions on how to check efi if it’s connected properly. The tank is rusted bad sooo I was seeing if the car starts with some starter fluid before getting into that. 

[Zed Head]

One way would be to test continuity to pin 73 at the EFI relay.  And I think that the ground wire is redundant, it's also connected to the intake manifold, grounding through the engine block.  While you're there at the battery check the fusible link.  They can look okay but be burned up inside.

The EFI relay is up above the hood release handle in the cabin.  If it's like most 280Z's, it's already been out a few times, might even just be hanging there.

This is the diagram you want to study to find check points.

 

[Zed Head]

By the way, if you disconnect the two EFI connections you should be able to work on the other stuff without it.  It's what people do when they switch  to carbs.

Disconnect here where I circled.  That is EFI power and ground.  Two red wires - thank you Nissan.  Then reconnect your battery, see if the engine still spins (the right way), get your coil power back, shoot some starting fluid, etc.  Let your sub-brain ponder the EFI power situation while you work on that stuff.

[Zed Head]

The length of the wires suggests that they are connected correctly though.  The positive connection is farthest away.  Hope there's no damage.

Your battery is actually what's flipped, which is how you got in to this mess.  Positive typically is under the fender edge.  More Nissan genius.

 

[280zdude]

Right that’s the next step but I tested the coil and that thing was toast. The internal resistance was through the roof! Need to do more studying on that as well 

[SteveJ]

4 minutes ago, Zed Head said:

The length of the wires suggests that they are connected correctly though.  The positive connection is farthest away.  Hope there's no damage.

Your battery is actually what's flipped, which is how you got in to this mess.  Positive typically is under the fender edge.  More Nissan genius.

 

And it's a very good idea to orient the battery the way Nissan designed. I had a battery with the positive toward the engine, and it wasn't secured properly. When the battery moved, the positive terminal made contact with the engine. Lots of smoke and burnt wires. With the way Nissan oriented the battery, the positive is less likely to come into contact with ground.

[280zdude]

The car actually came with the original battery flipped from Nissan lol I guess the dealer who installed it messed it up... I’m the second owner of the car