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5/19/13 10:37am - Original Message: 'electrical system troubleshooting'
N0JRS
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STERLING, CO - USA

Vette(s):
My Corvette is a 1978 L-82 Coupe with an automatic transmission. It has a Silver Anniversary paint scheme with an Oyster interior.

Joined: 1/10/2013
Posts: 43
Is there a previously written thread on troubleshooting a slow leak in the electrical system? I have to recharge my battery about every 4-5 days. I could sure use some help. Lynn
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5/19/13 2:02pm - Reply: 'Re: electrical system troubleshooting'
eldredjames Lifetime Member
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Temple City, CA - USA

Vette(s):
1969 Daytona Yellow. 350 / Automatic.

Joined: 10/3/2010
Posts: 361
One suggestion I got from YAHOO:
Disconnect your battery next time your car sits for a few days, if it starts fine you have a drain, if it's dead you probably need a new battery.

I searched our forums and found nothing but I'm sure something is there.  One the internet I found this site:
http://www.buzzle.com/articles/troubleshooting-car-electrical-problems.html

After that you may want to get a multimeter from Harbor Freight Tools.  Pretty cheap or free sometimes if you hit the right month and buy something else.

Good Luck.  Electrical problems are a bear to find!

Jim


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5/19/13 7:00pm - Reply: 'Re: electrical system troubleshooting'
N0JRS
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STERLING, CO - USA

Vette(s):
My Corvette is a 1978 L-82 Coupe with an automatic transmission. It has a Silver Anniversary paint scheme with an Oyster interior.

Joined: 1/10/2013
Posts: 43
Thank you, Jim:
When it sits for a few days, I have to boost it to get it started. I'll take it out and get it checked. When I disconnect it between using it, it always starts up easily. I appreciate you interest. I also need some help locating and installing heat shielding on the distributor and spark plug wires. I have the distributor cover, but no brackets or other shielding.  The battery issue is the big thing now.

Lynn
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5/19/13 9:00pm - Reply: 'Re: electrical system troubleshooting'
F4Gary Gold Member
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Grapevine, TX - USA

Vette(s):
1972 LT-1 convertible with factory air.

Joined: 8/26/2006
Posts: 869
It's not your battery.  You confirmed that yourself.

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5/19/13 10:53pm - Reply: 'Re: electrical system troubleshooting'
tb2k82ce Lifetime Member
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Lemon Grove, CA - USA

Vette(s):
1982 C3 Collectors Edition 44000 miles, sat in the sun most of it's life, My wife purchased it for me for fathers day in 2007 from her girl friend that had it for 19 years. It is on the road again. I'm retired but it is now my daily driver.

Joined: 10/17/2007
Posts: 2007

Using a meter in the Volt setting:

1. Put a volt meter between the negative battery cable end and the Negative battery terminal (of course with the neg disconnected)

2. If the meter ( 20 volt scale) swings / shows the wrong way or - volts , swap the meter leads. 

3. Next if the meter reads 12 volts , you have a drain , pull fuses till the reading is 0 volts.

4. Radios that have memory of stations and clock draw 1. volt to max1.8 volts

5. If all is still 12 volt with all fuses pulled, the main wires from the Alt would be the last to pull. If you find that the Alt is the Bleed out. You have a leaking Diode.

 

Using a meter in the amp setting:

1. Disconnect the battery positive lead.

2. Connect the digital multimeter between the battery positive lead and the battery positive terminal.

3. Select the multimeter to the ammeter function and turn the meter ON.

4. Check the multimeter reading less than 65mA (.065 A). That's your discharge rate and is normal for most cars with radios.

5. If the discharge rate is greater than 6mA, start removing and then re-installing fuses one at a time. When you remove each fuse, write down how much the discharge rate of the battery decreases.

6. After that, try removing and installing relays one at a time and write down how much the discharge rate drops for each relay.

7. Once you've completed this, identify all of the locations where you saw a significant decrease discharge rate. Using the factory wiring diagrams if necessary, determine all components supplied by those fuse/relay locations. Disconnect components from those circuits one at a time until you identify which one is the cause of the high current draw (as indicated by the ammeter).

What is the difference? Only thing is using the Volt (neg terminal process) protects your multimeter better.









|UPDATED|5/19/2013 8:53:23 PM (AZT)|/UPDATED|


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5/20/13 12:34am - Reply: 'Re: electrical system troubleshooting'
N0JRS
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STERLING, CO - USA

Vette(s):
My Corvette is a 1978 L-82 Coupe with an automatic transmission. It has a Silver Anniversary paint scheme with an Oyster interior.

Joined: 1/10/2013
Posts: 43
Thanks for the help.A buddy and I have a project to do tomorrow or Tuesday. I'm trying to get the car ready for the get together next month in Colorado Springs. Today I got the horn working. Yesterday I reapply see the headliner pieces to the T tops. I also have to work on the courtesy lights and the dome light. I appreciate the help. Lynn
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5/20/13 1:05am - Reply: 'Re: electrical system troubleshooting'
daveo76
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Joined: 8/25/2005
Posts: 831
I recently troubleshooted a similar problem. It turns out for me that it was factory alarm system. Got all that fixed now and I am down to .01 amps, which I assume is from my clock. The title of the thread is "good news and bad news" if you want to search - it was in the last few weeks. Good luck!

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1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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5/20/13 8:18am - Reply: 'Re: electrical system troubleshooting'
rraider1
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1152
the courtesy light timer is another source for draining the battery.

 



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Bob R
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5/21/13 5:15am - Reply: 'Re: electrical system troubleshooting'
crossfire1982
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Cramerton, NC - USA

Vette(s):
black 1982 coupe slate gray interior, 350 crossfire, 1985 fuel pump, Steeroids R&P conversion

Joined: 8/22/2006
Posts: 1094
Here is an old thread on parasitic draw, see if this helps any.
http://www.c3vr.com/vrforums/message440538.html#440543


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5/21/13 11:22pm - Reply: 'Re: electrical system troubleshooting'
N0JRS
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STERLING, CO - USA

Vette(s):
My Corvette is a 1978 L-82 Coupe with an automatic transmission. It has a Silver Anniversary paint scheme with an Oyster interior.

Joined: 1/10/2013
Posts: 43
Thanks for all the help. I plan to do the checking tomorrow or Thursday. I'll get back on how things went. I really appreciate it. I may have some questions on the alarm And the courtesy light timer. Right now the courtesy lights don't shut off.
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5/22/13 10:59am - Reply: 'Re: electrical system troubleshooting'
yostusota
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York, PA - USA

Vette(s):
1969 daytona conv. all original 350 350 380 4 sp w/air..and hard top

Joined: 5/18/2010
Posts: 1518
That sounds like you may have found an issue with the courtesy lights...not sure what year you have but if you're asking about shielding on the distributor then I assume you have an older c like mine...the brackets bolt to the intake bolts..there is only two of them on mine..one on each side. Can't remember if its the last bolt or the second to last bolt but I can check that when I get home. The draw is best found in the amp mode...just have everything turned off when you hook it up...like the radio and such...you want to test the car in its rested state. 6 ma would be a good chunk if your car reads that much but from what I've seen on some of these over the years it turns out to be a light timer or alarm issue if you have those still. The lower the better but it really is easy to find on these cars.

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5/22/13 2:40pm - Reply: 'Re: electrical system troubleshooting'
daveo76
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Joined: 8/25/2005
Posts: 831
Here's two recent strings regarding my electrical drain issue:
 
 
 
 


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1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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5/24/13 4:58pm - Reply: 'Re: electrical system troubleshooting'
N0JRS
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STERLING, CO - USA

Vette(s):
My Corvette is a 1978 L-82 Coupe with an automatic transmission. It has a Silver Anniversary paint scheme with an Oyster interior.

Joined: 1/10/2013
Posts: 43
I'm ready to start checking the courtesy light timer. Where would I find it? While I am at it, where is the theft alarm switch on a 78? Thanks for the help. 
Lynn
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5/24/13 6:58pm - Reply: 'Re: electrical system troubleshooting'
N0JRS
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STERLING, CO - USA

Vette(s):
My Corvette is a 1978 L-82 Coupe with an automatic transmission. It has a Silver Anniversary paint scheme with an Oyster interior.

Joined: 1/10/2013
Posts: 43
It was right behind the glove box just as stated. It was warm/hot to the touch. I'll order a new circuit board and put it in. I guess the next  step is to put things back together, enjoy a trip to our local Sonic Drive-in and check the battery voltage when I shut it off and see if it drops by morning. Thanks all for help. Now, to figure out how to get the alarm system to work, and then on to the ignition shielding. 

Thanks for the help. I'll get to Colorado Springs yet. 
Lynn
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5/24/13 10:58pm - Reply: 'Re: electrical system troubleshooting'
rraider1
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1152
The theft alarm sw is located in the left door lock

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Bob R
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5/24/13 11:12pm - Reply: 'Re: electrical system troubleshooting'
N0JRS
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STERLING, CO - USA

Vette(s):
My Corvette is a 1978 L-82 Coupe with an automatic transmission. It has a Silver Anniversary paint scheme with an Oyster interior.

Joined: 1/10/2013
Posts: 43
That is great. I need to pull the door panels tomorrow. The door locks don't work mechanically or electrically. There must be some kind of blockage of the rod that goes between the door lock and the lock mechanism. I can check the working of the door lock with the door panels off. How do I check to see that the alarm switch is working? Is there a thread that outlines checking out the alarm system for a 78 Vette? 

My wife and I did get to our local Sonic Drive-inn. I live in a small town. The car is lots of fun. The Chocolate fudge cream pie shake was great. Life isn't fair, but it is incredible. Thanks for the help.

Lynn
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5/25/13 10:55am - Reply: 'Re: electrical system troubleshooting'
rraider1
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1152
Here is the diagram for the 78 alarm if you need more info I might have some more stuff. I have pictures of the switches in the doors of my 77
 
 
If you have sport mirrors could you take a picture from inside where the mirrors mount for another thread on installing sport mirrors?





|UPDATED|5/25/2013 8:55:55 AM (AZT)|/UPDATED|


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Bob R
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5/31/13 9:07pm - Reply: 'Re: electrical system troubleshooting'
N0JRS
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STERLING, CO - USA

Vette(s):
My Corvette is a 1978 L-82 Coupe with an automatic transmission. It has a Silver Anniversary paint scheme with an Oyster interior.

Joined: 1/10/2013
Posts: 43
Well, I won't be getting the new courtesy light circuit board until after June 7-8, so I might as well start working on the alarm system. I know that it is as old as the hills and just as archaic, but it would be nice to have it working. Can anyone help me with a trouble shooting thread specifically covering the 78+ Vettes? I have the diagrams copied, and will start to sort out the components. I'll see if I can  see if the alarm goes off, locate the alarm horn, and try to check for continuity. Are there any things or places to check first? Any help would be appreciated. 

Lynn
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6/1/13 1:22am - Reply: 'Re: electrical system troubleshooting'
daveo76
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Vancouver, WA - USA

Vette(s):
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Joined: 8/25/2005
Posts: 831
Lynn, here's a recent post on getting my alarm working in my '76.  I know there are differences in that system between '76 and '78 but you may get some general use out of this.  



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1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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6/1/13 8:24am - Reply: 'Re: electrical system troubleshooting'
rraider1
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1152
this diagram will help if you do not have it
 


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Bob R
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