Jump to content

Leaking Voltage?


Recommended Posts

I'm trying to troubleshoot a new fuse panel on a 1973 Porsche 911 and can't seem to get past the first two fuses. The "tops" of both 1 & 2 have 12.7V directly from the battery, as they should. I thought it was weird that without the fuses installed, only the first fuse's LED indicator light turned on. I did some investigating and see that it will only light when there is a load on the "bottom," so maybe this isn't an issue.

However, I also checked for voltage at the various posts. As noted, the top of Fuse 1 registers 12.7V. With no fuse installed, the bottom registers 1.9V. I pulled the bottom wire and again tested for voltage. The wire itself showed none, but the bottom post now registered 11.25V. Reinstalling the wire caused the voltage to drop back down to 1.9V and the LED to light.

I tried the same tests on Fuse 2. The only difference I found was that the voltage remained at 11.25V at the lower post regardless of whether it's wire was attached or not. There was no voltage at the wire.

Obviously, both bottom posts jump to 12.7V when I install the fuses.

So far nothing has blown up or caught fire, but I'm concerned about voltage appearing where I don't expect it. Your assistance would be greatly appreciated. 

Rich

Link to comment
Share on other sites

Non issues both:

Correct, the LED only lights if the fuse is blown (missing) when there is power to the circuit.  This is documented in the install guide.  It also offers a visual diagnostic function for tracing faults.  E.g. if you are wanting to know if you light switches are working, take out the fuses for the lighting and activate the switch - the LED should light up.

Regarding the voltage drop, with the fuse out you are simply seeing the voltage drop across the LED (it's a diode).  Remember also, using your meter is creating a 'load' of sorts.

 

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...