Electrical Short Help! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

breeh · 01-30-2003, 06:57 PM

I have a short that I cannot seem to chase down. What I have done:

* Disconnected (-) battery cable and installed multimeter between cable and battery post. This is showing a 16 volt current with everything off.

* Pulled fuses and unfused connections at fuse box one by one. Still have the 16 volt draw.

What else can I do to try and isolate this? The weird thing is that it only seems to drain the battery when it is raining. This is a problem since I live in western Washington and that is what it does here this time of year. I have not been able to test this observation to see if I do still have the draw when everything is dry.

Any ideas?????

**68 Stepside** · 01-30-2003, 07:54 PM

perhaps it has something to do with the voltage regulator being stuck (if you have the OE charging system setup)??? I don't know.

TTT

Blue Beard · 01-30-2003, 08:02 PM

breech:

I'm having a fun time with the same type of problem.

Have found several burnt or over heated wires.

About ready to buy new wiring.

Gone thru the same things you have so far, no results.

Was told that some after market radios being connected wrong with the memory wire can cause problems.

Redid my radio just in case, no good.

Would appreciate it if you find anything to let me know, and I will do the same.

cdowns · 01-30-2003, 08:21 PM

all your doing with the multimeter is measuring the voltage in the battery volts don't draw amps draw . if it happens mostly during rainy conditions chack first the primary wire going to the starter for cracks etc also the wires that go to the rearend they're located along the left frame rail after that i'd go to the regulator and altenator

Blue Beard · 01-30-2003, 08:28 PM

I can understand the possibility of the starter wires. I haven't got there yet.

But why the wires going to the rearend.

Something to do with the lighting wires?

breeh · 01-30-2003, 08:44 PM

No external regulator anymore.

If everything is off there shouldn't be any measurable current, right??

Gordo · 01-30-2003, 08:51 PM

You will be better off using a 12V test light and connecting it between the neg bat post and the neg cable instead of using the voltmeter unless you have an amp setting on the meter. If you have a draw it will light the light, the stronger the draw the brighter the light will get. Pull the fuses again and also try disconnecting the alt and or reg while monitoring the test light.

72K10 · 01-30-2003, 08:52 PM

Breeh,

I chased a ghost short for a couple of weeks before I found the problem. Sounds like your's might be the same.

Does your windshield or cowl leak into the cab? If it does, or even if it doesn't, check your dimmer switch. Just take out the two screws and pull the plug. If its dirty and rusty around the connections, I'll bet that's your problem. Costs less than $4 to replace.

Hope this is it.

Chris

cdowns · 01-30-2003, 08:52 PM

right current is AMPS not volts

jmanz69 · 01-30-2003, 08:57 PM

I had the same problem with the dimmer switch in my 69 when it was on the road. But it didn't really drain the battery. Could be because it started on fire while I was driving though. Had to go cut a pigtail off another truck to put a new switch on. I bet it is your problem. They are easy to forget about down there.

breeh · 01-30-2003, 09:46 PM

I'm not going to debate the terminology because I am definitely not an electrical guy. So pick whatever term is appropriate volt or amps. Let's assume that using a light between the cable and the terminal and seeing if it lights up implies that there is some kind of excitation of the electrons within that wire which means that there is a closed circuit, right? Now if I substitute a meter which measures the existence of electricity (volts, amps, whatever) I am doing much the same thing as that light bulb. My understanding is that if the vehicle is turned off that there should not be any live circuits. This implies that a light will not light nor will my meter measure anything. If this is not correct, please someone tell me.

My cab floor becomes soaked when it rains (not because of the windshield but because the radio antenna hole and some bad cab seals). So, I am going to go check my dimmer switch. Thanks for suggesting that! That make sense.

Gordo · 01-30-2003, 10:13 PM

Just an example, you could have a memory mode in your am/fm radio that holds your stations and clock when everything else is turned off, this will show a 12 V draw on your meter but it only draws very little current (amps). The one wire alt you installed may show 12 V constantly but very little actual current draw, provided it's a healthy alt.

breeh · 01-30-2003, 10:17 PM

Thanks Gordo for helping an electrical knucklehead through this. I think that my multimeter has an amperage setting. If not, I will see if I can rig up a light.

tom hand · 01-30-2003, 10:27 PM

How did you convert your alternator? An internaly regulated alternater that is not wired correctly will work and put a draw on the battery. It ussally won't pull it down to where it won't crank over night, but will show up if you let it sit for a day or two

breeh · 01-30-2003, 10:42 PM

Tom, the alternator is a one wire job that was built professionally. It has been in the truck for 4 months without any problems (until now).

01-30-2003, 06:57 PM	#1
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	Electrical Short Help! I have a short that I cannot seem to chase down. What I have done: * Disconnected (-) battery cable and installed multimeter between cable and battery post. This is showing a 16 volt current with everything off. * Pulled fuses and unfused connections at fuse box one by one. Still have the 16 volt draw. What else can I do to try and isolate this? The weird thing is that it only seems to drain the battery when it is raining. This is a problem since I live in western Washington and that is what it does here this time of year. I have not been able to test this observation to see if I do still have the draw when everything is dry. Any ideas????? __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

01-30-2003, 07:54 PM	#2
68 Stepside huh? Join Date: May 2000 Location: Washington, Illinois Posts: 5,690	perhaps it has something to do with the voltage regulator being stuck (if you have the OE charging system setup)??? I don't know. TTT __________________ Someday when I'm lonely, Wishing you weren't so far away, Then I will remember Things we said today. RIP El Jay

01-30-2003, 08:02 PM	#3
Blue Beard Registered User Join Date: Jan 2003 Location: Washington State Posts: 8,831	Short Circuit breech: I'm having a fun time with the same type of problem. Have found several burnt or over heated wires. About ready to buy new wiring. Gone thru the same things you have so far, no results. Was told that some after market radios being connected wrong with the memory wire can cause problems. Redid my radio just in case, no good. Would appreciate it if you find anything to let me know, and I will do the same. Attached Images __________________ 1970 Chev CST 2003 Harley Fatboy 1975 Chevrolet Step Van 1956 Chev Bel Air 1977 Blazer 2WD For Sale $3000.00 1978 Blazer 2WD For Sale $7000.00 1978 Silverado 2005 Monte Carlo

01-30-2003, 08:21 PM	#4
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	all your doing with the multimeter is measuring the voltage in the battery volts don't draw amps draw . if it happens mostly during rainy conditions chack first the primary wire going to the starter for cracks etc also the wires that go to the rearend they're located along the left frame rail after that i'd go to the regulator and altenator __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

01-30-2003, 08:28 PM	#5
Blue Beard Registered User Join Date: Jan 2003 Location: Washington State Posts: 8,831	Short I can understand the possibility of the starter wires. I haven't got there yet. But why the wires going to the rearend. Something to do with the lighting wires? __________________ 1970 Chev CST 2003 Harley Fatboy 1975 Chevrolet Step Van 1956 Chev Bel Air 1977 Blazer 2WD For Sale $3000.00 1978 Blazer 2WD For Sale $7000.00 1978 Silverado 2005 Monte Carlo

01-30-2003, 08:44 PM	#6
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	No external regulator anymore. If everything is off there shouldn't be any measurable current, right?? __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

01-30-2003, 08:51 PM	#7
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	You will be better off using a 12V test light and connecting it between the neg bat post and the neg cable instead of using the voltmeter unless you have an amp setting on the meter. If you have a draw it will light the light, the stronger the draw the brighter the light will get. Pull the fuses again and also try disconnecting the alt and or reg while monitoring the test light. __________________ 1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist.

01-30-2003, 08:52 PM	#8
72K10 Registered User Join Date: Dec 1999 Location: New York Posts: 288	Breeh, I chased a ghost short for a couple of weeks before I found the problem. Sounds like your's might be the same. Does your windshield or cowl leak into the cab? If it does, or even if it doesn't, check your dimmer switch. Just take out the two screws and pull the plug. If its dirty and rusty around the connections, I'll bet that's your problem. Costs less than $4 to replace. Hope this is it. Chris __________________ RLTW 70C10 72K10 72K10 Cheyenne 72C10 Cheyenne Super

01-30-2003, 08:52 PM	#9
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	right current is AMPS not volts __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

01-30-2003, 08:57 PM	#10
jmanz69 Careful, they attack... Join Date: Aug 2001 Location: Waterford, MI, USA Posts: 1,107	I had the same problem with the dimmer switch in my 69 when it was on the road. But it didn't really drain the battery. Could be because it started on fire while I was driving though. Had to go cut a pigtail off another truck to put a new switch on. I bet it is your problem. They are easy to forget about down there.

01-30-2003, 09:46 PM	#11
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	I'm not going to debate the terminology because I am definitely not an electrical guy. So pick whatever term is appropriate volt or amps. Let's assume that using a light between the cable and the terminal and seeing if it lights up implies that there is some kind of excitation of the electrons within that wire which means that there is a closed circuit, right? Now if I substitute a meter which measures the existence of electricity (volts, amps, whatever) I am doing much the same thing as that light bulb. My understanding is that if the vehicle is turned off that there should not be any live circuits. This implies that a light will not light nor will my meter measure anything. If this is not correct, please someone tell me. My cab floor becomes soaked when it rains (not because of the windshield but because the radio antenna hole and some bad cab seals). So, I am going to go check my dimmer switch. Thanks for suggesting that! That make sense. __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

01-30-2003, 10:13 PM	#12
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	Just an example, you could have a memory mode in your am/fm radio that holds your stations and clock when everything else is turned off, this will show a 12 V draw on your meter but it only draws very little current (amps). The one wire alt you installed may show 12 V constantly but very little actual current draw, provided it's a healthy alt. __________________ 1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist.

01-30-2003, 10:17 PM	#13
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	Thanks Gordo for helping an electrical knucklehead through this. I think that my multimeter has an amperage setting. If not, I will see if I can rig up a light. __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

01-30-2003, 10:27 PM	#14
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	How did you convert your alternator? An internaly regulated alternater that is not wired correctly will work and put a draw on the battery. It ussally won't pull it down to where it won't crank over night, but will show up if you let it sit for a day or two __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

01-30-2003, 10:42 PM	#15
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	Tom, the alternator is a one wire job that was built professionally. It has been in the truck for 4 months without any problems (until now). __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"



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