Continuity between positive and negative battery terminals when battery is unplugged?? Help Needed

Pantera6

Hesitantly Boosting
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Location
Vic
First Name
CE
Drive
2000 Legnum VR4 Type-S Manual w/ Recaros + Momo Wheel + Moonroof + Roofrails
Hi All,

For those of you in the know , would you be able to confirm if, when the battery is removed, if there should be continuity between the positive and negative battery posts?

Specifically, I would like to know if the Legnum electrical system is such that there is continuity between the negative battery terminal (which is connected to chassis ground) and the second positive cable that goes from the positive battery terminal to the fuse/relay block by the battery (when the battery is disconnected)?

I removed the battery and did some cleaning/re-grounding of terminals and thought I’d take a multimeter reading for continuity between the positive and negative terminals to ensure there are no shorts (one would not expect there to be continuity between the positive and negative terminals).

Well, it appears that I do have continuity between the afore mentioned negative terminal and positive terminal that goes to the fuse/relay block, which seems to suggest a short circuit somewhere, BUT, I’m not sure if this is also by design. I should have taken a reading before I took things apart, but I didn’t and now I don't want to connect the battery before I'm sure. Hence, if someone could confirm if continuity between the negative terminal and the positive terminal is normal (ideally with their battery also disconnected) I would greatly appreciate it before I start the long process of trouble shooting.

Many Thanks in advance.
 
G

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Could be residual charge held in the electrical system, that is why you pump your brakes and flick your headlights on and off when resetting the ECU, to discharge that energy.
That may not be the correct answer though lol
 

BCX

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SA
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Bill
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2000 Galant Type-V
1997 MK Triton GLS [6G74 conversion]
2019 i30 N-Line
Do you have an amp?

What looks to be a short might be the power capacitors in various devices (like amps, etc) that are in parallel with battery for filtering.

These caps have a low resistance/high charge current when empty.
 

Rabit

Leaving Skid Marks
Location
Qld
First Name
Robert
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2000 Legnum Mint with 44589ks when I got it. Now with black leather seats. After 3 years of fun some terminal engine bay wiring issues raised their ugly heads and it died. I Now drive a 2002 Legnum and have retired the 2000 to spare parts duty.
There are lots of gadgets in the car that are on all the time. Thats why you should disconnect the battery if the car is to be idle for a couple of months. Things like the clock and the memory for the radio etc. That would explain the continuity.
 

Pantera6

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Vic
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CE
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2000 Legnum VR4 Type-S Manual w/ Recaros + Momo Wheel + Moonroof + Roofrails
Thanks to all who replied. I did a bit more troubleshooting and found the culprit.

For those interested, the answer to my original question is NO – there should not be any continuity between the positive and negative battery terminals when the battery is unplugged (as this would indicate a short circuit!).
However, when I tested for continuity, I was getting an indication of a short, and I traced it to the No 1 fuse (the interior door/dome light) in the fuse/relay box next to the battery. It’s a bit silly, but the reason there was continuity was that the passenger door was open when I was testing, and of course that created a completion of the circuit (for the door light) and I was reading this continuity as a short – phew!

So the lesson is, if you’re ever testing for electrical continuity between the battery’s positive and negative terminals (to see if there’s a short) make sure that all electrical items that would otherwise close a circuit are off/doors closed/boot closed. If there is still continuity, then the easiest way to find the real short is to start pulling the fuses one at a time until the continuity is broken, and that would be the culprit. Luckily, my grounding work seemed to be all OK!


Do you have an amp?

What looks to be a short might be the power capacitors in various devices (like amps, etc) that are in parallel with battery for filtering.

These caps have a low resistance/high charge current when empty.

As a matter of fact, the car’s been out of service for the last three months while I took on the mega project (for me) of installing a full SQ set-up and DIN gauges in the dash, but that’ll be for another thread – if anyone was interested.
Thanks for all your help!
 

sanchez

Leaving Skid Marks
Location
NSW
First Name
rodrigo
Drive
legnum
There would be continuity through the lighting circuit but you would of seen a resistive component (globe) and basic ohm's law would allow a basic understanding of current flow through the tested circuit...
 
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