The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 02-15-2004, 08:17 PM   #1
Ripley Bryant
Registered User
 
Join Date: Mar 2003
Location: Salem, Oregon
Posts: 67
Unhappy Tracing Electrical Problem....

Ok.. I'm getting frustrated here...

I have a short or drain somewhere that will drain my battery if it sits for 3 or more days.

I have been trying all day to figure out where it is with no luck.

Here's my attack so far... I have my multitester connected between my battery and the positive battery cable.

Registers 12v...

I have removed all fuses from the fuse panel and unplugged the wiring from the radio that the PO installed.

No Change, Registers 12v drain...

I have one by one unplugged and reconnected every plug in the engine bay... No change.

I have unplugged the dome/cargo light wiring... No change

I have removed a bunch of extraneous wiring the PO had to help clean things up a bit.

Under the dash, if it wasn't connected, I removed it..

Under the truck, I traced 3 wires, two for a plug the PO had for the canopy lights, removed those... No change.

Traced the wiring for a bed mounted gas tank/diverter valve, removed the wiring... no change.


At this point, I just need some guidance. Am I correct in thinking that with the ignition off, and the doors closed that my multimeter between the + side of the battery and the + battery cable should register 0v?

Any suggestions on how to proceed from here?

The only obvious thing I haven't checked is the wiring for the tow lights. There is an aftermarket (I think) bunch of wiring for this on the firewall, some of which I removed when removing disconnected wires and the 2 toggle switches the PO had under the dash. One was for the bed mounted gas tank, and the 2nd was connected to the trailer brake stuff...

Other than this drain/short, everything works fine.
__________________
Ripley Bryant
Salem, Oregon

'77 Chevrolet Silverado 20 - 454 BB, TH400, Factory wood floor longbed
'75 Fiat X1/9 - my AutoXer
'77 Fiat X1/9 - her AutoXer
'81 Fiat 2000 Spider - under construction
'00 Dodge Neon - Commuter
'00 Dodge Grand Caravan - Family bus
Ripley Bryant is offline   Reply With Quote
Old 02-15-2004, 08:57 PM   #2
NeCrOmAnCeR
Registered User
 
NeCrOmAnCeR's Avatar
 
Join Date: Feb 2004
Location: Hodgenville, Ky
Posts: 735
You're approach of removing fuses etc.. is correct. However, with the positive cable disconected and the meter conected between the battery and cable it will many times measure battery voltage due to oil and other contaminants on the starter etc. I believe you are thinking of a current draw test. If you're meter can measure DC current, switch the meter to do so and connect it as before between the battery and cable. With everything off doors closed etc. I would expect the battery drain to be a few tens of milliamps (If you have a radio with a memory feature) or zero otherwise. Do the same thing you have before by removing fuses until you find the problem. I hope this helps,

Last edited by NeCrOmAnCeR; 02-15-2004 at 09:32 PM.
NeCrOmAnCeR is offline   Reply With Quote
Old 02-16-2004, 12:24 AM   #3
Blue Beard
Registered User
 
Blue Beard's Avatar
 
Join Date: Jan 2003
Location: Washington State
Posts: 8,831
I had a similiar problem, went down the same lines.........

One major issue was the positive cable was grounding against the block behing the manifold.

Another thread indicated that the wires going down the drivers frame rail has wiring that sometimes goes bad....
__________________
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
Blue Beard is offline   Reply With Quote
Old 02-16-2004, 12:25 AM   #4
Ripley Bryant
Registered User
 
Join Date: Mar 2003
Location: Salem, Oregon
Posts: 67
Necromancer,

Thanks...

I did measure the amperage and on the 30milliamp setting on my meter, it pegs the meter. On the 10Amp setting, it doesn't register.

Have since reconnected all the things I unplugged and installed all my fuses. Will resume the hunt next weekend. Will just disconnect the battery when it's parked for now.
__________________
Ripley Bryant
Salem, Oregon

'77 Chevrolet Silverado 20 - 454 BB, TH400, Factory wood floor longbed
'75 Fiat X1/9 - my AutoXer
'77 Fiat X1/9 - her AutoXer
'81 Fiat 2000 Spider - under construction
'00 Dodge Neon - Commuter
'00 Dodge Grand Caravan - Family bus
Ripley Bryant is offline   Reply With Quote
Old 02-16-2004, 12:30 AM   #5
Ripley Bryant
Registered User
 
Join Date: Mar 2003
Location: Salem, Oregon
Posts: 67
Blue Beard,

I was under there, tracing wiring for the canopy lights and the auxilliary tank wiring and removed that stuff. Didn't see anything obvious like melted wires/insulation, etc...

What exactly do you mean by the wires sometimes go bad in the driver's side framerail?

Thanks,
__________________
Ripley Bryant
Salem, Oregon

'77 Chevrolet Silverado 20 - 454 BB, TH400, Factory wood floor longbed
'75 Fiat X1/9 - my AutoXer
'77 Fiat X1/9 - her AutoXer
'81 Fiat 2000 Spider - under construction
'00 Dodge Neon - Commuter
'00 Dodge Grand Caravan - Family bus
Ripley Bryant is offline   Reply With Quote
Old 02-16-2004, 12:48 AM   #6
Prerunner1982
Registered User
 
Prerunner1982's Avatar
 
Join Date: Oct 2002
Location: Edmond, OK
Posts: 5,904
i have a similar problem, except instead of 3 days its 6hrs. i have dont everything except disconnect the alt. It appears to be going bad as well, so like yourself i disconnect the battery every night.
__________________
Jon
1982 Chevy Silverado 350/th350.... RETIRED
1993 Jeep XJ 2 door(Cherokee) 4wd 4.0ltr/AX-15 (5spd)/NP231
....
Oklahoma Roll Call
Prerunner1982 is offline   Reply With Quote
Old 02-16-2004, 01:03 AM   #7
Blue Beard
Registered User
 
Blue Beard's Avatar
 
Join Date: Jan 2003
Location: Washington State
Posts: 8,831
The post mentioned the wires on the drivers rail rub where you can't see and creates a bare spot that creates short.....
__________________
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
Blue Beard is offline   Reply With Quote
Old 02-16-2004, 12:31 PM   #8
TROYLV
Registered User
 
Join Date: Oct 2002
Location: LAS VEGAS, NV.
Posts: 157
try disconnecting the wires from the alt. sometimes diodes go bad and will alow small current to flow to ground. if this is the case the alt won't be long going totaly bad and draining the battery in about 5 minutes.
__________________
troy wilson
TROYLV is offline   Reply With Quote
Old 02-16-2004, 07:53 PM   #9
Ripley Bryant
Registered User
 
Join Date: Mar 2003
Location: Salem, Oregon
Posts: 67
Thanks Troy!

I'll give that a shot tonight.
__________________
Ripley Bryant
Salem, Oregon

'77 Chevrolet Silverado 20 - 454 BB, TH400, Factory wood floor longbed
'75 Fiat X1/9 - my AutoXer
'77 Fiat X1/9 - her AutoXer
'81 Fiat 2000 Spider - under construction
'00 Dodge Neon - Commuter
'00 Dodge Grand Caravan - Family bus
Ripley Bryant is offline   Reply With Quote
Old 02-17-2004, 06:58 PM   #10
flip66
Registered User
 
flip66's Avatar
 
Join Date: Jan 2004
Location: Garland TX Dallas area
Posts: 658
Has seen were the alternator is week but not bad. If you test it will show 12 volts output but will only show 20 amps output when it should be at least 60 plus.
flip66 is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 01:38 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com