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.

fast 99

Full Access Member
Joined
Dec 31, 2021
Posts
2,029
Reaction score
2,933
Location
Spokane, Washington
First Name
Brian
Truck Year
81,85
Truck Model
K20
Engine Size
350
Some items in vehicles don't have a draw until after they have been powered up. So you have to unhook battery, hook up meter,amps, turn on key, turn off. If your meter only does 10A, make sure you don't have a bunch of crap turned on when doing this, -heater, wipers, etc, bot DO turn on radio, especially if aftermarket. This is why mechanics use a battery switch, install it, run vehicle, turn everything on, turn truck off, hook up meter across disconnect switch, open switch. This way everything gets activated.
You just made confirmed my case for using a shunt. Very easy to exceed 10 amps.

Will add a majority of draws I have seen were caused by aftermarket items, such as alarms, remote start, radios, amps, ect.
 

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
5,446
Reaction score
8,683
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
I will once again state it is nice to make a lead for your meter with an inline fuse lower than the meter fuse,cheap,easy to check,easy to change.
 

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
Last thing I can think is did you blow either of the fuses and is that making the meter not read?
Good luck!
Im willing to bet your right. When I first started even before I made a post. I had the MM set up just like in the
video on 10A and leads were located all correct. When I placed one lead on the negative battery cable and the other lead on the battery post, it sparked pretty good. (lead tips) both. How do I find out what fuse to change out?
the 10A does not look blown. is it supposed to change colors or something. I also took the plug out the alt and will see tomorrow if batt is drained.

You must be registered for see images attach
 
Last edited:

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
I will once again state it is nice to make a lead for your meter with an inline fuse lower than the meter fuse,cheap,easy to check,easy to change.
Im going to do that! :happy160:
 

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
I have seen were caused by aftermarket items, such as alarms, remote start, radios, amps, ect.
Cool to know. I have none of that stuff. :cheers:
 

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
5,446
Reaction score
8,683
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
Im willing to be your right. When I first started even before I made a post. I had the MM set up just like in the
video on 10A and leads were located all correct. When I placed one lead on the negative battery cable and the other lead on the battery post, it sparked pretty good. (lead tips) both. How do I find out what fuse to change out?
I also took the plug out the alt and will see tomorrow if batt is drained.

You must be registered for see images attach
If you had a meter you could check resistance of the fuses. 0 is good OL is bad. If you do not have another meter,a piece of wire a dome light bulb and three hands.With the 10 amp fuse one end set on negative battery cable hold the wire pinched to the other end of the fuse. Hold the wire to one end of the dome light bulb touch the other end to the positive battery post. If the light lights the fuse is good,if not check to make sure you are making contact everywhere if still no light, fuse is bad. If the fuse is good measure resistance of the other fuse if it reads open put your 10a fuse where the other fuse was,read the fuse again. Still open that fuse is bad.
 
Last edited:

Robert Bare

Full Access Member
Joined
Sep 13, 2020
Posts
107
Reaction score
166
Location
MT
First Name
Robert
Truck Year
1978
Truck Model
k20
Engine Size
5.7
The big fuse on the right is the amp, and is sealed, have to check with a meter or such. Your meter will still work on volts and ohms, use it to test the 10a one after you take it out.
PS, when an alt. goes bad, as far as causing a draw, is usually a diode, and unplugging the little wires will tell you nothing, you have to remove the big cable from the back.
 

Broken85

Junior Member
Joined
Jan 14, 2024
Posts
19
Reaction score
20
Location
Cumberland, NJ
First Name
A
Truck Year
1985
Truck Model
K10
Engine Size
350
You must be registered for see images attach
I know you said this truck is stock and unhacked, but what’s the story of this box?? Is that a snow plow relay or something? Looks like maybe something after market. Also, I assume this is a single battery set up, but if it’s not, are both batteries good?? One bad battery will ruin both of them. With that kind of draw, a test light should shine like the sun between the battery and the terminal. If it’s bright, it ain’t right. If you have an IR camera you can also check for heat under the hood on a cold morning to see what is on and drawing current
 

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 must be registered for see images attach
I know you said this truck is stock and unhacked, but what’s the story of this box?? Is that a snow plow relay or something? Looks like maybe something after market. Also, I assume this is a single battery set up, but if it’s not, are both batteries good?? One bad battery will ruin both of them. With that kind of draw, a test light should shine like the sun between the battery and the terminal. If it’s bright, it ain’t right. If you have an IR camera you can also check for heat under the hood on a cold morning to see what is on and drawing current
Single battery. That box is a Blue Sea fuse box as a stand alone for my 2 front fans with relays. power comes from the side terminals on the battery and 2 toggle switches on the dash for control. :happy160:

You must be registered for see images attach
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
6,970
Reaction score
12,220
Location
Auburn, Washington
First Name
Todd
Truck Year
1986, 1977
Truck Model
K20, C10
Engine Size
454, 350
I think the little fuse is like 1/2amp for the lower settings.
And it should work on ohms you can test the fuse.
Or pop another fuse in it if you have any old glass fuses. Preferably 10A or less for obvious reasons.
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
6,970
Reaction score
12,220
Location
Auburn, Washington
First Name
Todd
Truck Year
1986, 1977
Truck Model
K20, C10
Engine Size
454, 350
Single battery. That box is a Blue Sea fuse box as a stand alone for my 2 front fans with relays. power comes from the side terminals on the battery and 2 toggle switches on the dash for control. :happy160:

You must be registered for see images attach
I like those little Blue Sea fuse boxes. I put the same on the K20 for accessory loads.
 

Latest posts

Forum statistics

Threads
44,161
Posts
950,631
Members
36,273
Latest member
dannyphx
Top