Help finding a short, Who's good at ELECTRICAL???

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Nasty-LSX

TogetherforeverCovid19
Joined
Nov 22, 2014
Posts
1,395
Reaction score
1,737
Location
HOUSTON TX
First Name
Mi Hung Lo
Truck Year
85/86/87
Truck Model
c10/k10/k20
Engine Size
LSX
Let me start of by saying this truck(1985 K20) is unhacked, all in factory order,factory stock.
I have a battery draw. If I let it sit more than a day the battery gets low enough that I need
a jump start. I have to disconnect the battery every nite so it will start the next day.


Here is the problem, I have seen a ton of videos on finding a short. My problem is When I disconnect
the Neg cable and use my multimeter (just like in the video) I get 0.00 on the multimeter. Well as you
know thats showing there is no draw and everything is in good working order. What other option do I
have to pinpoint this issue?. This video is very clear with the multimeter, Almost every video out there
is the same to trace a short, but none say what to do if your getting 0.00 on the multimeter :cheers:

xc_hide_links_from_guests_guests_error_hide_media
 

fast 99

Full Access Member
Joined
Dec 31, 2021
Posts
2,078
Reaction score
3,043
Location
Spokane, Washington
First Name
Brian
Truck Year
81,85
Truck Model
K20
Engine Size
350
Try using a test light in series with either battery cable. If it lights =draw. Another way is amp scale on MM in series, however if draw exceeds internal MM fuse it will blow. 3rd way is with a shunt. But usually, one if the above methods should turn up something. Others will come along with additional suggestions.
 

NC595

Junior Member
Joined
Sep 1, 2024
Posts
5
Reaction score
4
Location
North East US
First Name
Bryan
Truck Year
1986
Truck Model
C10
Engine Size
305
Just to clarify, you're definitely setting it to DC Amps, and not DC V, right? I only ask because I've made that mistake more times than I care to admit!

To elaborate on the video, you're putting your meter in series with the negative cable and the battery and the meter should be showing the amount of current headed to ground through the meter. Volt meters work in parallel, amp meters work in series.

That being said, I'd definitely start with what Fast 99 says above. If you're seeing the current read 0.00 while in series or other indications of zero-draw, then there's a possibility what you're looking at is intermittent and just not present when you're using the meter. I defer to those more experienced than me at that point though.

Hope this is helpful! Lets see how it plays out.
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
7,053
Reaction score
12,374
Location
Auburn, Washington
First Name
Todd
Truck Year
1986, 1977
Truck Model
K20, C10
Engine Size
454, 350
You don’t say what setting, V or A you’re using. To my understanding you’ll always “see” 12V across the neg battery post to ground. That is the voltage potential of the battery.
To check for a draw, you measure current. IE amps.
A draw on the battery connects the + to ground, completing the circuit.
Unintentional draws do this as well.

You need to measure amps across the neg to ground.
Example (old vehicles with no intentional draws like stereo memory or other electrical components)
The 86 K20 has a parasitic draw. Has for a while. Not sure if since we bought it or if it’s something I added. I suspect it’s the Chinesium headlight relay kit I bought. Because the year plus I had it apart doing paint and body it would keep an old refurb battery alive amazingly. Now it will kill a good battery in a couple-three months ish.
It has a 40mA draw (0.04A). But it won’t light a test light. However opening the door (dome lights) will light a test light.
It shows 12v across neg to ground though as it should.

The 77 c10 for comparison has 0-1 mA draw (basically zero). Still shows 12V across neg post to gnd. Doesn’t light a test light on the same test (obviously) but does if the dome light is on.

If you’re losing the battery in 1-2 days it’s a significant draw. I’d think it would light an old incandescent test bulb. It will certainly show up on a multimeter. My guess is 100s of mA or possibly a full amp or more draw. If you have a good 80-100 ah battery it would take a 1 amp draw to draw it down 50% in about 2 days. (If I’m mathing right). And 50% is basically dead. Lights may glow but it won’t crank.
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
7,053
Reaction score
12,374
Location
Auburn, Washington
First Name
Todd
Truck Year
1986, 1977
Truck Model
K20, C10
Engine Size
454, 350
Try using a test light in series with either battery cable. If it lights =draw. Another way is amp scale on MM in series, however if draw exceeds internal MM fuse it will blow. 3rd way is with a shunt. But usually, one if the above methods should turn up something. Others will come along with additional suggestions.
Test light requires a healthy amp draw. Remember what is being tested is the current flowing through the chassis (like a live short). It’s like the chassis is the positive post of a “battery” but it’s the stray voltage going to ground where it shouldn’t. (Been a while since my EE classes though…lol I’m old)
OP could be pulling enough amps to light a test light. Test light is for crude measurement of a pretty significant short.
To the other suggestion by somebody. It’s likely not an intermittent short if it’s repeatable as @Nasty-LSX alluded to.
Regardless it WILL be visible on a multimeter. Not sure why it isn’t for @Nasty-LSX.
 

Nasty-LSX

TogetherforeverCovid19
Joined
Nov 22, 2014
Posts
1,395
Reaction score
1,737
Location
HOUSTON TX
First Name
Mi Hung Lo
Truck Year
85/86/87
Truck Model
c10/k10/k20
Engine Size
LSX
Just to clarify, you're definitely setting it to DC Amps, and not DC V, right? I only ask because I've made that mistake more times than I care to admit!
Thanks NC595. Yes I followed that video to a tee. Made sure all was correct since I cant get anything over 0.00
 

Nasty-LSX

TogetherforeverCovid19
Joined
Nov 22, 2014
Posts
1,395
Reaction score
1,737
Location
HOUSTON TX
First Name
Mi Hung Lo
Truck Year
85/86/87
Truck Model
c10/k10/k20
Engine Size
LSX
Try using a test light in series with either battery cable.
is this what your talking about? I get 12.2 volts when I go from neg cable to neg batt post.
You must be registered for see images attach
 

Nasty-LSX

TogetherforeverCovid19
Joined
Nov 22, 2014
Posts
1,395
Reaction score
1,737
Location
HOUSTON TX
First Name
Mi Hung Lo
Truck Year
85/86/87
Truck Model
c10/k10/k20
Engine Size
LSX
You don’t say what setting, V or A you’re using.
Im doing it exactly like the video shows to do it, and hundreds others, Checking in 10 amps on meter.
I am also not using a cheap 10 dollar meter, just dont understand why it wont show a draw :cheers:

You must be registered for see images attach
 

Nasty-LSX

TogetherforeverCovid19
Joined
Nov 22, 2014
Posts
1,395
Reaction score
1,737
Location
HOUSTON TX
First Name
Mi Hung Lo
Truck Year
85/86/87
Truck Model
c10/k10/k20
Engine Size
LSX
The batt is only 4 month old. The truck did it with the previous battery
so I know it is not a bad battery. As long as it stays disconnected I keep 12.2 volts.
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
7,053
Reaction score
12,374
Location
Auburn, Washington
First Name
Todd
Truck Year
1986, 1977
Truck Model
K20, C10
Engine Size
454, 350
Im doing it exactly like the video shows to do it, and hundreds others, Checking in 10 amps on meter.
I am also not using a cheap 10 dollar meter, just dont understand why it wont show a draw :cheers:

You must be registered for see images attach
Nice multi meter!
Check in milliamps and/or make sure you’re plugged into the right pins with your leads on the multimeter.
 

fast 99

Full Access Member
Joined
Dec 31, 2021
Posts
2,078
Reaction score
3,043
Location
Spokane, Washington
First Name
Brian
Truck Year
81,85
Truck Model
K20
Engine Size
350
Know a test light is a crude test and would be a significant draw. Tossed that out because most people have one and simple is sometimes best, easiest.

OP is doing something wrong [or a bad meter] if in series on the amp or milli amp scale shows nothing. May need to check meter internal battery.

A shunt is one of the best ways to check a draw but usually not required.
 

Nasty-LSX

TogetherforeverCovid19
Joined
Nov 22, 2014
Posts
1,395
Reaction score
1,737
Location
HOUSTON TX
First Name
Mi Hung Lo
Truck Year
85/86/87
Truck Model
c10/k10/k20
Engine Size
LSX
Nice multi meter!
Check in milliamps and/or make sure you’re plugged into the right pins with your leads on the multimeter.
Ok i went from setting my multimeter up like in all the video's and got nothing. I set it up in milliamps
and low and behold I got a 2.11. Is that my draw? I pulled every fuse and that # never reduced

You must be registered for see images attach
You must be registered for see images attach


This is how I was checking before but got nothing!

You must be registered for see images attach
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
7,053
Reaction score
12,374
Location
Auburn, Washington
First Name
Todd
Truck Year
1986, 1977
Truck Model
K20, C10
Engine Size
454, 350
^ For mA, the red lead should be in the lower left plug on the multimeter. Where it says milliamps and microamps.
You have it in the voltage and resistance + plug looks like.
2 mA is nothing. That’s 2/1000 or 0.002A. Your battery would not go dead forever at 2mA. But I don’t trust that reading.
 

Nasty-LSX

TogetherforeverCovid19
Joined
Nov 22, 2014
Posts
1,395
Reaction score
1,737
Location
HOUSTON TX
First Name
Mi Hung Lo
Truck Year
85/86/87
Truck Model
c10/k10/k20
Engine Size
LSX
What a retard :Pshyco:, OK let me try again! :cheers:
 

Nasty-LSX

TogetherforeverCovid19
Joined
Nov 22, 2014
Posts
1,395
Reaction score
1,737
Location
HOUSTON TX
First Name
Mi Hung Lo
Truck Year
85/86/87
Truck Model
c10/k10/k20
Engine Size
LSX
Ok, I get 0.00 still. I'm guessing this is going to be something I need to leave to experts. I know online help is really hard when
the people that are helping cant see whats in front of them. Im gonna try a different multimeter with the 10A setting and see if
I can get a draw.

You must be registered for see images attach
You must be registered for see images attach
 

Forum statistics

Threads
44,346
Posts
954,891
Members
36,584
Latest member
brunoD
Top