 Electrical Gremlins, Headlight switch related? |
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| scoobykvn |
 May 30 2011, 10:55 AM
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#1
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Member  Group: Members Posts: 142 Joined: 6-July 06 From: columbus, ohio Member No.: 6,388 Region Association: Upper MidWest  |
I am having some issues with battery drain. When my battery is hooked up and headlights off, some of my gauge lights are still on. When I turn the lights on they swap (on turn off and off turn on). I tried another switch I have and it does the same thing. If I unhook the ground cable on the battery and leave the pos cable on, the gauge lights on previously are still getting a small amount of current (I can see a dim glow). If I unhook the blue and black wires from the headlight switch the lights go off. Anyone have any ideas?
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Replies(1 - 10)
| Spoke |
May 30 2011, 12:48 PM
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#2
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Jerry Group: Members Posts: 6,986 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None 
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Which lights are on and which are off? Each of the gauge illumination bulbs are single-ended. That is, they only have 1 wire (hot) where the ground is the gauge chassis.
If you totally disconnect the NEG of the battery, you will not have an drain. Not sure how you did your cable removal test. |
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| scoobykvn |
May 31 2011, 04:51 PM
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#3
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Member Group: Members Posts: 142 Joined: 6-July 06 From: columbus, ohio Member No.: 6,388 Region Association: Upper MidWest |
So I did a little checking today but did not have too much time. What I noticed is this; With battery connected but headlight switch off, at least the 3 center console gauges had lights on, not sure of the dash lights because bulbs could be out. The wierd thing that I noticed was when I disconnect the 2 sets of black/blue wires for gauge lights from the head light switch, the lights go mostly out but still have some current going to them because they have a slight glow. When I take those 2 sets of wires and touch them together, the bulbs turn bright like before. This is when I ran out of time.
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| Mike Bellis |
May 31 2011, 05:52 PM
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#4
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Resident Electrician Group: Members Posts: 8,345 Joined: 22-June 09 From: Midlothian TX Member No.: 10,496 Region Association: None 
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Without having more information, here is my opinion... You have lost a ground connection to some device in your car. Since current takes the path of least resistance, the "device" is backfeeding through the dash lights finding ground. This would explain the dim lights. Current does not need a true ground to flow. It only needs a "more negative" part of the circuit. Check every BROWN wire in your electrical system. There is one loose, missing or other... Other would be an aftermarket radio grounding through the illumination circuit, or similar...
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| scoobykvn |
Jun 1 2011, 07:01 PM
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#5
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Member Group: Members Posts: 142 Joined: 6-July 06 From: columbus, ohio Member No.: 6,388 Region Association: Upper MidWest |
I have yet to find a loose ground connection or one the has paint or dirt on it. This is what I still dont understand; If I unplug the 2 sets of black/blue wires from the back of the headlight switch, the bulbs go dim. When I touch those 2 sets of wires together the bulb gets bright like it has full voltage. I assume if those wires are unplugged then the bulbs should have no power going to them. Are there any other ideas out there for me to check? I will have all day tomorrow to look into this. If it matters the wiring harness is from a '76 but it is in a '70. And would it matter if not all the wires are hooked up? like the side blinkers in the front, or the license plate lights, interior light switches in the door.
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| Mike Bellis |
Jun 1 2011, 07:11 PM
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#6
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Resident Electrician Group: Members Posts: 8,345 Joined: 22-June 09 From: Midlothian TX Member No.: 10,496 Region Association: None
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Do you have this?
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| Mike Bellis |
Jun 1 2011, 07:12 PM
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#7
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Resident Electrician Group: Members Posts: 8,345 Joined: 22-June 09 From: Midlothian TX Member No.: 10,496 Region Association: None
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And this...
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| Mike Bellis |
Jun 1 2011, 07:15 PM
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#8
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Resident Electrician Group: Members Posts: 8,345 Joined: 22-June 09 From: Midlothian TX Member No.: 10,496 Region Association: None
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QUOTE(scoobykvn @ Jun 1 2011, 06:01 PM)  If it matters the wiring harness is from a '76 but it is in a '70. And would it matter if not all the wires are hooked up? like the side blinkers in the front, or the license plate lights, interior light switches in the door. Make sure the wire that are loose are insulated and not touching the chassis. I posted a but 73 schematic 95% of the wires are the same. |
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| 904svo |
Jun 1 2011, 07:30 PM
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#9
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904SVO Group: Members Posts: 1,118 Joined: 17-November 05 From: Woodstock,Georgia Member No.: 5,146 |
Make sure the brown wires are connected to the gauges. The gauges are insulated
from ground by the rubber rings. If there not connected there will be a feedback path thru the lights. |
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| scoobykvn |
Jun 2 2011, 03:50 PM
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#10
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Member Group: Members Posts: 142 Joined: 6-July 06 From: columbus, ohio Member No.: 6,388 Region Association: Upper MidWest |
I think I fixed my issues. On one of the center console gauges the wires were no hooked up properly. Not sure if that was me when I installed it or PO, but it is fixed now, I hope (leaving the battery hooked up overnite to see if it holds charge). One thing I noticed in all this searching is that my fuel pump stays on the whole time the key is in the on position, not just for a second or two. I am running carbs with the pump up front. I won't have time to check on it until next week since I will be out of town, but I was hoping for some pointers.
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| Mike Bellis |
Jun 2 2011, 07:36 PM
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#11
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Resident Electrician Group: Members Posts: 8,345 Joined: 22-June 09 From: Midlothian TX Member No.: 10,496 Region Association: None
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Wiith fuel injection the pump runs for a few seconds and stops until the engine turns over. The ECU controls the pump. When you switch to carbs, the pump has to run all the time.
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