The importance of GOOD grounds! - Team Camaro Tech
Electrical & Wiring Troubleshooting electrical.

 
LinkBack Thread Tools Display Modes
post #1 of 12 (permalink) Old Sep 7th, 09, 07:42 AM Thread Starter
Moderator
Kevin
 
KevinW's Avatar
 
Join Date: Jul 2000
Location: Millstone, NJ
Posts: 11,040
Red face The importance of GOOD grounds!

Well, testing out the electrical system in my orange car after I rebuilt ALL the harnesses. My brake lights were acting wierd, the pass side would only light dimly (drv was good!) and the dash lights came on weakly too. After swapping out the light switch, turn signal harness (just restored the column and turn signal mech, so I thought that might be the problem), no change.

Parking lights in the rear would also not come on at all.

Started on check 12V to and through the harnesses and to the light sockets, that was good.

Did an ohm check, and everything checked out, but still no workee.

Then I started checking the ohms with the 12V on, hit the pass inboard light socket to the ground screw and wala!, Lights!! did some more digging and ran a jumper between the wire terminal (not the screw!) and the ground terminal on the pass inboard socket and lights again!

So even though the ohm meter said I had a ground to the socket, it was in-fact too weak to take the load. I have to take the harness apart and see what is happening.

Lesson learned!

Kevin


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
KevinW is offline  
Sponsored Links
Advertisement
 
post #2 of 12 (permalink) Old Sep 7th, 09, 08:50 AM
Gold Lifetime Member
 
Join Date: Mar 2008
Location: Port St. Lucie, FL
Posts: 907
Re: The importance of GOOD grounds!

Kevin, is that the latest pic in your signature?

1969 Chevrolet Camaro 396 SS X-66

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


1967 Chevrolet Camaro RS Convertible

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Brandan is offline  
post #3 of 12 (permalink) Old Sep 7th, 09, 12:35 PM Thread Starter
Moderator
Kevin
 
KevinW's Avatar
 
Join Date: Jul 2000
Location: Millstone, NJ
Posts: 11,040
Re: The importance of GOOD grounds!

Nope It is much closer to looking like a real car, but since it is not startable yet I have not been able to pull it outside for fresh pics.

Kevin


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
KevinW is offline  
 
post #4 of 12 (permalink) Old Sep 7th, 09, 03:06 PM
Tech Team
Matt
 
Join Date: Aug 2009
Location: MI
Posts: 40
Re: The importance of GOOD grounds!

Let me second your good ground!! I dont know if the tail lights in a 69 ground like the ones in a 67 do (the bulb socket grounds to the tail light housing) but I hate that method!! Mine work fine now but I could see it being trouble later. The other grounds that are huge and commonly over looked is the ground strap between the body and frame and the small wire (minimum 12 awg) that should go from the battery post to the radiator core support. Another thing people do is those friggin battery terminals that bolt to the end of the wire, just spend the 9$ and get a new cable factory made with the ends factory crimped!! Those bolt on ones always cause trouble...
mattsk8 is offline  
post #5 of 12 (permalink) Old Sep 7th, 09, 03:21 PM
Gold Lifetime Member
 
Join Date: Mar 2008
Location: Port St. Lucie, FL
Posts: 907
Re: The importance of GOOD grounds!

post some new pics when you can.......... we would like to see them

1969 Chevrolet Camaro 396 SS X-66

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


1967 Chevrolet Camaro RS Convertible

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Brandan is offline  
post #6 of 12 (permalink) Old Sep 7th, 09, 03:58 PM Thread Starter
Moderator
Kevin
 
KevinW's Avatar
 
Join Date: Jul 2000
Location: Millstone, NJ
Posts: 11,040
Re: The importance of GOOD grounds!

Well, this was how it looked back in July.


Kevin


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
KevinW is offline  
post #7 of 12 (permalink) Old Sep 7th, 09, 04:41 PM
Senior Tech
 
Join Date: Mar 2002
Location: Austin, TX, USA
Posts: 5,277
Re: The importance of GOOD grounds!

Quote:
Originally Posted by KevinW View Post
.

...Started on check 12V to and through the harnesses and to the light sockets, that was good...Did an ohm check, and everything checked out, but still no workee.

Then I started checking the ohms with the 12V on...
This is why I advocate the voltage drop method again and again. The voltage drop method would have told you almost immediately that the problem was in the ground leg and with a few more test you could have isolated the exact ground.

Volt meters are high impedance devices (high internal resistance) so if there is any connection at all, they'll read a full 12V until the circuit is loaded. The meter draws so little current that a pencil line on a piece of paper will conduct enough current for the meter to read.

Measuring resistance theoretically works, but often times, the currents are so large that a few tenths of an ohm (or hundreths of an ohm for starter motors) is all it takes to create a bad connection. Digital volt-ohm meters often have trouble reading resistances of 1 ohm. Reading ohms with the circuit powered is off the map though - the results are unpredictable. Glad it worked for you, but I wouldn't recommend it as a standard troubleshooting procedure. It's doubtful the meter will be harmed, but the readings are ???

The voltage drop method on the other hand is fool proof. It doesn't care what the state of charge is of your battery, or how many amps you're pulling through the circuit. I posted the process dozens of times so I won't go into those details here.

I know this sounds a bit like Monday morning quarterbacking, but thought I'd point out how voltage and resitance measurements can be misleading as the OP discovered.

Dave
========================
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI
dnult is offline  
post #8 of 12 (permalink) Old Nov 7th, 11, 08:47 PM
Senior Tech
BARTELL
 
Join Date: Oct 2007
Location: HAZEL CREST, IL
Posts: 381
Re: The importance of GOOD grounds!

Matt:
Ground wire from the battery to the core support on a 67?
BTELL67 is offline  
post #9 of 12 (permalink) Old Nov 8th, 11, 03:35 AM Thread Starter
Moderator
Kevin
 
KevinW's Avatar
 
Join Date: Jul 2000
Location: Millstone, NJ
Posts: 11,040
Re: The importance of GOOD grounds!

Bartell, Do you have the AIM for your car? Grounds from the batt usually go to the fender. Positive feed goes to the stud behind the batt on the core support. Then there are a couple of ground straps that ground the front sheetmetal to the body. It should be all documented in the AIM.

Kevin


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
KevinW is offline  
post #10 of 12 (permalink) Old Nov 8th, 11, 06:59 AM
Senior Tech
BARTELL
 
Join Date: Oct 2007
Location: HAZEL CREST, IL
Posts: 381
Re: The importance of GOOD grounds!

Kevin:
I have all of that done. Ground strap from firewall to valve cover, and short one on pass side from frame to body. Ground from battery to block and to inner fender. I was asking Matt what he meant about ground from battery to core support on a 67 as this is not in AIM.
BTELL67 is offline  
post #11 of 12 (permalink) Old Nov 8th, 11, 08:59 AM Thread Starter
Moderator
Kevin
 
KevinW's Avatar
 
Join Date: Jul 2000
Location: Millstone, NJ
Posts: 11,040
Re: The importance of GOOD grounds!

Matt's post was 2 years ago. Hope he figured it out by now

Kevin


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
KevinW is offline  
post #12 of 12 (permalink) Old Nov 8th, 11, 12:22 PM
Senior Tech
BARTELL
 
Join Date: Oct 2007
Location: HAZEL CREST, IL
Posts: 381
Re: The importance of GOOD grounds!

Right!
BTELL67 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may 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
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome