Park / tail lights fuse keeps blowing

[wil84911]

Just happened (edit: prob inaccurate as it may have happened longbefore I started using the park lights. See resolution on post #34) . As soon as the fuse touches the box it lits then blows. Haven’t touch anything electrical except pull the radio out which wasn’t even connected and that was a week ago. Checked the wiring behind the radio but saw nothing that would cause shorting. Could someone kindly provide some clues? Thanks in advance.

 

 

12/71 2.6 block E88 heads triple weber 3/2 Mallory Abarth Tokico 1-3/4 sways

 

 

 

 

[JSM]

I'll start with the obvious, no ill will intended, you have the correct amperage fuse installed correct?

And this condition happens regardless if you turn the parking lights on?  And your isolating to the parking lights on only, not stepping on the brake pedal?

Edited October 24, 2017 by JSM

[wil84911]

I'll start with the obvious, no ill will intended, you have the correct amperage fuse installed correct?

And this condition happens regardless if you turn the parking lights on?  And your isolating to the parking lights on only, not stepping on the brake pedal?

 

It’s okay. I thought about that too. Got the correct 20A but it was blowing right after getting on the fusebox.

 

 

12/71 2.6 block E88 heads triple weber 3/2 Mallory Abarth Tokico 1-3/4 sways

[Mikes Z car]

My 240Z (early 1970 model) uses a 20A for the parking/tail lights.  I think I remember that if the 32V rating is on one end of the fuse the amp rating is on the other end and can be hard to read in my experience.  So if one end says 32V the other end should say 20A.

Edited October 25, 2017 by Mikes Z car

[wil84911]

My 240Z (early 1970 model) uses a 20A for the parking/tail lights.  I think I remember that if the 32V rating is on one end of the fuse the amp rating is on the other end and can be hard to read in my experience.  So if one end says 32V the other end should say 20A.

Thanks.. checked and updated my reply.


12/71 2.6 block E88 heads triple weber 3/2 Mallory Abarth Tokico 1-3/4 sways

[JSM]

So with the lights off, you put the fuse in and it blows? Have you turned the switch on and off a few times to make sure it's not shorting somehow internally? 

Sounds like you have a grounded short if it's not in the switch. I'm assuming you've been driving it with the lights on at some point  since you've got it and this just started. 

Aside from the radio you didn't mess with the fuse block in anyway and no lose wires running up under the fuse block?

[wil84911]

So with the lights off, you put the fuse in and it blows? Have you turned the switch on and off a few times to make sure it's not shorting somehow internally? 
Sounds like you have a grounded short if it's not in the switch. I'm assuming you've been driving it with the lights on at some point  since you've got it and this just started. 
Aside from the radio you didn't mess with the fuse block in anyway and no lose wires running up under the fuse block?

Yes lights off she blows . And yes I’ve drive it with lights working fine to this point. Haven’t mess with anything yet. Still checking around the fuse block but haven’t found anything though I suspect problem may be there. Thanks


12/71 2.6 block E88 heads triple weber 3/2 Mallory Abarth Tokico 1-3/4 sways

[SteveJ]

Why do you expect the problem is around the fuse block? 

In electrical troubleshooting, the first thing to do is isolate. In this case, remove the cover from the steering column and disconnect the 6 wire connector on the headlight switch. Use a test light across the fuse and see if it lights up. If it does, continue troubleshooting.

Let's follow your hunch about the fuse block. Disconnect your battery and remove the block. Look for debris that could touch the inner side of the fuse to the chassis. If you don't see anything there, it's likely in your dash harness.

If it's the dash harness, chances are that the green/blue wire has been chafed somewhere or someone tapped it as a continuously hot source. (Think aftermarket radio here.) Where the wire was tapped may have some bare wire that is coming into contact with the chassis or dash frame.

[wil84911]

Why do you expect the problem is around the fuse block? 
In electrical troubleshooting, the first thing to do is isolate. In this case, remove the cover from the steering column and disconnect the 6 wire connector on the headlight switch. Use a test light across the fuse and see if it lights up. If it does, continue troubleshooting.
Let's follow your hunch about the fuse block. Disconnect your battery and remove the block. Look for debris that could touch the inner side of the fuse to the chassis. If you don't see anything there, it's likely in your dash harness.
If it's the dash harness, chances are that the green/blue wire has been chafed somewhere or someone tapped it as a continuously hot source. (Think aftermarket radio here.) Where the wire was tapped may have some bare wire that is coming into contact with the chassis or dash frame.

Just guessing as I remember getting a spark pulling the radio out (yes aftermarket). I will try your suggestions. Thanks


12/71 2.6 block E88 heads triple weber 3/2 Mallory Abarth Tokico 1-3/4 sways

[JSM]

9 hours ago, SteveJ said:

Why do you expect the problem is around the fuse block? 

In electrical troubleshooting, the first thing to do is isolate. In this case, remove the cover from the steering column and disconnect the 6 wire connector on the headlight switch. Use a test light across the fuse and see if it lights up. If it does, continue troubleshooting.

Let's follow your hunch about the fuse block. Disconnect your battery and remove the block. Look for debris that could touch the inner side of the fuse to the chassis. If you don't see anything there, it's likely in your dash harness.

If it's the dash harness, chances are that the green/blue wire has been chafed somewhere or someone tapped it as a continuously hot source. (Think aftermarket radio here.) Where the wire was tapped may have some bare wire that is coming into contact with the chassis or dash frame.

That may have been my fault Steve.  Since it was fine until he pulled the radio, I was thinking he might have gotten a lose wire, coin or something under there.

Wil, do everything Steve says.  He's the Picasso of electrical gremlins around here.  I'm still in kindergarten drawing stick figures!

Edited October 25, 2017 by JSM

[wil84911]

That may have been my fault Steve.  Since it was fine until he pulled the radio, I was thinking he might have gotten a lose wire, coin or something under there.
Wil, do everything Steve says.  He's the Picasso of electrical gremlins around here.  I'm still in kindergarten drawing stick figures!

Thanks folks. Appreciate the help so far. Kinda feel I didn’t leave the aircooled Porsche forum


12/71 2.6 block E88 heads triple weber 3/2 Mallory Abarth Tokico 1-3/4 sways

[SteveJ]

25 minutes ago, JSM said:

That may have been my fault Steve.  Since it was fine until he pulled the radio, I was thinking he might have gotten a lose wire, coin or something under there.

Wil, do everything Steve says.  He's the Picasso of electrical gremlins around here.  I'm still in kindergarten drawing stick figures!

Keep in mind that I know a lot about troubleshooting because I've done enough things to cause trouble, whether it was in my cars or in my projects at work.