The Stovebolt Page Forums Home | FAQ | Forum | Swap Meet | Gallery | Tech Tips | Events | Features | Search | Hoo-Ya Shop
Work those trucks!




Share what you're up to this summer!

Stovebolt Site Search
 
Old Truck Calendars
Months of truck photos!
Nothing like an old truck calendar

Stovebolt Calendars

Check for details!


Who's Online Now
1 registered members (tomctomc), 538 guests, and 3 spiders.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums48
Topics116,219
Posts927,491
Members42,581
Most Online940
Apr 5th, 2017
Image Posting Policy
Previous Thread
Next Thread
Print Thread
Page 1 of 3 1 2 3
Voltage drain needs investigation #1329261 Tue Oct 08 2019 09:47 PM
Joined: Sep 2011
Posts: 1,832
L
Lugnutz Offline OP
Shop Shark
Driving my 63 one day and my horn starts to blow. Disconnected horn and it stopped.
Usually that’s caused by a short in the column near the upper bearing.
Next day my battery is dead.
Charged battery again but when I checked, I found a 10V voltage drop at the negative battery terminal. The column is completely out of the truck but the 10V drain is still there.
What items should I check first?
Alternator?
Horn relay? (It’s only 6 months old)
Suggestions?
Key ignition switch?

All the lights work properly. No HEI in this truck.
Thanks in advance for your ideas.

Last edited by Lugnutz; Tue Oct 08 2019 09:49 PM.
Re: Voltage drain needs investigation [Re: Lugnutz] #1329265 Tue Oct 08 2019 10:23 PM
Joined: May 2005
Posts: 1,617
B
beltfed Offline
Shop Shark
Sorry but I and maybe others don’t understand what you mean by “a 10v voltage drop”. Can you explain your problem a little better.


Six volt guy living in a twelve volt world
Re: Voltage drain needs investigation [Re: Lugnutz] #1329275 Tue Oct 08 2019 11:43 PM
Joined: Jul 2000
Posts: 705
G
Gord&Fran Offline
Shop Shark
How did you disconnect the horn?

If you disconnected it at the horn, the horn relay is still energized and drawing current. Is the relay warm?

Disconnect the brown wire (one that goes up the column to the button) at the horn relay.


Gord
----
1954 1/2 ton 235 4 speed
Re: Voltage drain needs investigation [Re: Gord&Fran] #1329284 Wed Oct 09 2019 12:28 AM
Joined: Sep 2011
Posts: 1,832
L
Lugnutz Offline OP
Shop Shark
Originally Posted by Gord&Fran
How did you disconnect the horn?

If you disconnected it at the horn, the horn relay is still energized and drawing current. Is the relay warm?

Disconnect the brown wire (one that goes up the column to the button) at the horn relay.

The entire steering column is out of the truck, so the brown wire from the steering wheel is no longer connected to the harness. I reconnected the horn and the horn no longer blows, so I doubt the horn relay is stuck.

Re: Voltage drain needs investigation [Re: beltfed] #1329285 Wed Oct 09 2019 12:35 AM
Joined: Sep 2011
Posts: 1,832
L
Lugnutz Offline OP
Shop Shark
Originally Posted by beltfed
Sorry but I and maybe others don’t understand what you mean by “a 10v voltage drop”. Can you explain your problem a little better.

When I disconnect the negative cable on the battery, any shorted circuits in the truck can be detected and measured by connecting a digital multimeter between the negative cable and battery ground. I am reading 10V. I did not measure amps (but should have though). A 12V bulb will show (or should show) a 12V voltage drop. A shorted circuit in something else may not show a 12V drop because of the inherent resistance and amp flow. V=IR
It’s not drawing enough current to blow a fuse because if the fuse blows it interrupts the circuit.

Last edited by Lugnutz; Wed Oct 09 2019 12:37 AM.
Re: Voltage drain needs investigation [Re: Lugnutz] #1329287 Wed Oct 09 2019 01:19 AM
Joined: May 2005
Posts: 1,617
B
beltfed Offline
Shop Shark
If you put the DVM in series with the ground circuit and read 10 volts I would think your battery is weak for whatever reason. A DVM draws very little current in voltage mode, at best a milliampere or so. On the other hand, with all circuits off, you should read zero voltage as that’s an open circuit. On your horn relay, did you remove the horn wire or the voltage side of the relay. If you removed just the horn wire, the relay could still be closed and drawing current if the ground side of the relay is grounded.


Six volt guy living in a twelve volt world
Re: Voltage drain needs investigation [Re: Lugnutz] #1329289 Wed Oct 09 2019 01:22 AM
Joined: Mar 2019
Posts: 114
S
Shakey61 Offline
Shop Shark
Lugnutz,

Using the method you described, you should have had your voltmeter on an 'Amp' setting, and you would have read a current draw off the battery. Current is measured in series; volts in parallel.

I just went out and checked on my truck: on a battery charged to 12.8v, doing what you described yielded a volt reading of 10.2v, slowly climbing to 12.8v before I lost interest. Testing volts in that manner is basically reading the battery voltage through the wiring harness, and doesn't provide any useful information. You haven't hit upon your problem.

Check for a current draw, starting with the battery. Then check current draw on your relay, since you already suspect that. If the draw of the relay isn't nearly your total draw on the battery, then the problem is elsewhere. Current flow is a first-order effect, voltage drop is a secondary effect. (As an example, the stereo in my truck draws about 300mA even when off...running the clock, holding memory presets, etc.)

Think of electricity as water in a pipe...voltage is pressure (psi), current is flow (gpm).

-Kevin


Last edited by Shakey61; Wed Oct 09 2019 01:25 AM.

This is what happens when you live with a house-full of women, the wife and daughters name all the cars:
1960 Impala - "Frankie" (Frank Sinatra)
1961 Apache - " 'Mater Jr." (wrecker)
1972 SuperBeetle Convertible - "Juliet"
1976 SuperBeetle Convertible - "Olaf"
1988 Alfa Romeo Spider Veloce - "Romeo"
Re: Voltage drain needs investigation [Re: Lugnutz] #1329294 Wed Oct 09 2019 01:52 AM
Joined: Sep 2011
Posts: 1,832
L
Lugnutz Offline OP
Shop Shark
Back to the horn relay.
I doubt the relay is the problem. I’ve hooked the horn back up. No more horn. If relay was stuck the horn should sound.

Re: Voltage drain needs investigation [Re: Lugnutz] #1329295 Wed Oct 09 2019 01:54 AM
Joined: Feb 2001
Posts: 1,262
T
Tommy Offline
Shop Shark
Jay,
When it's dark outside, look and see if the alternator light on the dash has a dim glow to it. Sometimes when a diode goes bad it will run the battery down. Or you could just disconnect the alternator all together and see if the battery goes down.


Tommy
59 apache 1/2t
261 short stepside
Re: Voltage drain needs investigation [Re: Lugnutz] #1329299 Wed Oct 09 2019 02:10 AM
Joined: Mar 2019
Posts: 114
S
Shakey61 Offline
Shop Shark
If you no longer think it's the horn relay, measure the current draw at the battery as described above. Then start checking each wire attached to the battery circuit of the fusebox.

-Kevin


This is what happens when you live with a house-full of women, the wife and daughters name all the cars:
1960 Impala - "Frankie" (Frank Sinatra)
1961 Apache - " 'Mater Jr." (wrecker)
1972 SuperBeetle Convertible - "Juliet"
1976 SuperBeetle Convertible - "Olaf"
1988 Alfa Romeo Spider Veloce - "Romeo"
Page 1 of 3 1 2 3

Moderated by  Rusty Rod 

Home | FAQ | Forum | Swap Meet | Gallery | Tech Tips | Events | Features | Search | Hoo-Ya Shop
Powered by UBB.threads™ PHP Forum Software 7.7.3