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[C2] Wiring Questions

 
Old 02-08-2019, 11:24 PM
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ph31mwl
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I am almost done reassembling my 65 Roadster. Last week I thought I would be starting it for the first time in 4 years but ran into some wiring issues. I am getting current on some of the ground wires. Specifically, the ground wires that go to the back of the car. I am also having some issues with the light switch. I have attached 2 pictures. One is the body connector that connects the wiring from the back of the car to the main connector under the panel. When I disconnect the connector from the back of the car and test each pin of the front connector the black and white wires (on the right side of the picture) both light up the test light. The black one is a ground and goes to the back of the car and grounds the lights. I donít think it should not be lighting up the test light. Not sure if voltage should be on the white wire at all times. The other picture is the wiring connector that attaches to the light switch. When I test each wire with the test light the red wire (hot from the battery and should light up the test light) as well as the white wire next to it, the green wire and the light brown wire on the left side of the picture all light up the test light. Should all four of these wires light up the test light or did I mess up something when reinstalling the wiring harness. Any advice and guidance that can be offered will be greatly appreciated. Mark


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Old 02-09-2019, 08:59 AM
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65GGvert
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The white wire goes to the rear courtesy light (in the storage compartment rear wall) It should NOT read voltage with the rear body connector disconnected. It will with the plug connected because the orange feeds voltage to the lamp anytime the battery is connected, and then opening the door or rotating the headlight switch to courtesy light position provides the ground. If it's reading voltage on the front side with the plug disconnected, then your instrument cluster has 12v (or some voltage, hard to tell with a test light) where it should be ground. With both doors closed and headlight switch in the courtesy off position, rear body connector not connected, you should read nothing (open) on the white wire. Opening the door would put a ground on the other side of the lamps and IF, I repeat IF, you have voltage on the ground circuit would give the symptoms you describe.
Two possible scenarios. One, the color coding of the battery wires is not as you would suspect. The brown (reddish) battery cable is ground, (if stock) and the black battery cable is positive (12v). Many times those cables are switched and cause lots of odd problems, because 12v is put on ground and everything becomes wired backwards.
Two: If the wiring of the cables is correct, there are also two other black wires at the starter. One goes on the starter mounting bolt and the other goes to the solenoid. Make sure the black ground wire that goes under the starter bolt is correct and grounds the heater and wipers and that the battery cable black wire is connected to the starter solenoid and NOT the starter mounting bolt.

One last thought, the instrument cluster (and therefore everything at the rear of the car) grounds via a black wire in the radio three pin connector. There are two black wires on the car side of the radio connector coming out of the same pin. The short one with the ring terminal MUST be grounded to the Zbar via a screw to ground almost all things electrical from the dash back to the rear. Sometimes an aftermarket radio is added and that ground ends up either cut or disconnected and you lose ground to all those things mentioned, allowing a floating ground to accept voltage through lamps and other electrical devices.

IF you do have voltage on the ground, one of those three things should be the problem. Be sure to post back if you find anything unusual in your troubleshooting.

Last edited by 65GGvert; 02-09-2019 at 09:00 AM.
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Old 02-09-2019, 11:40 AM
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65GGvert, thank you for your response. You suggested a few things to check that I will do this morning. I put a complete new wiring harness in the car in 1983 but did not drive it much over the years (around 10K in 36 years) and the car has always been kept in my garage so I don’t think the harness has been degraded much. I have added several “upgrades” to the car while doing the current rebuild (Edelbrock Proflo-3 EFI, Vintage Air, Detroit Speed headlight door opener and windshield wiper, Dakota Digital dash gauges and cruise control) but I am sure that I wired these items in correctly. I did just order a new light switch as the Detroit Speed headlight doors would not open and close unless I wiggled the switch rod around. . I am sure the problem I am having something is something simple like in the places you pointed out like I have connected a positive wire to ground thus putting power on the ground wire system. I was getting too wrapped up in thinking about all the additional wiring I did and did not consider the basic places that you pointed out. Will let you know what I find. Thank you again for your response. Mark
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Old 02-09-2019, 07:38 PM
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65GGvert, totally due to your response to my post I had a good day today. I checked the wires going to the starter and they were fine. The white wire in connector that attaches to the light switch is still on when disconnected from the switch as well as the red wire (hot from the battery and should light up the test light) the white wire next to it, the green wire and the light brown wire on the left side of the picture.

I went to the wiring in the dash to find the radio connector. I did install an aftermarket radio and just wrapped up the connector with electrical tape. So I grounded the short black wire with the terminal ring. While doing that I lost something under the radio and stuck a screwdriver under it to fish out the part. I noticed that when doing so I was making sparks when it hit the radio stabilizer. Well, that is not good. I loosened the stabilizer up and found that it was pinching the power wire to the radio. Rerouted the wire and turned on the key to see what would happen. OMG, the radio worked, the clock worked, the electric fuel pump worked, the Detroit Speed headlight doors and windshield wipers worked perfectly, and there was no more voltage on the black wire on the front side of the connector, and the green wire in the light switch connector had no voltage.

What remains is finding why the white wire in the light switch connector is still on and also the white and orange wires in the body connector. One thing, when I connect the connector to the light switch and the doors are closed the bulb on the passenger side is off, the bulb on the drive side is on but the filament in the bulb is on very little and the light in the back is fully on. Any ideas??

Also since you know a lot about this electrical stuff can you enlighten me about a fuse box question I have. I checked all the fuses with the trouble light. When the ignition switch is off, the bottom two fuses (10 Amp) show power on both sides of the fuse. When I turn the ignition on the bottom 2 and the top 3 fuses (15, 10 &3) show power on both sides. The third one up from the bottom does not show any power key on or key off. Why is that? I want to thank you very much for you help with this. You saved me many hours of frustration. Mark
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Old 02-09-2019, 08:03 PM
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Originally Posted by ph31mwl View Post
65GGvert, totally due to your response to my post I had a good day today. I checked the wires going to the starter and they were fine. The white wire in connector that attaches to the light switch is still on when disconnected from the switch as well as the red wire (hot from the battery and should light up the test light) the white wire next to it, the green wire and the light brown wire on the left side of the picture.

I went to the wiring in the dash to find the radio connector. I did install an aftermarket radio and just wrapped up the connector with electrical tape. So I grounded the short black wire with the terminal ring. While doing that I lost something under the radio and stuck a screwdriver under it to fish out the part. I noticed that when doing so I was making sparks when it hit the radio stabilizer. Well, that is not good. I loosened the stabilizer up and found that it was pinching the power wire to the radio. Rerouted the wire and turned on the key to see what would happen. OMG, the radio worked, the clock worked, the electric fuel pump worked, the Detroit Speed headlight doors and windshield wipers worked perfectly, and there was no more voltage on the black wire on the front side of the connector, and the green wire in the light switch connector had no voltage.

What remains is finding why the white wire in the light switch connector is still on and also the white and orange wires in the body connector. One thing, when I connect the connector to the light switch and the doors are closed the bulb on the passenger side is off, the bulb on the drive side is on but the filament in the bulb is on very little and the light in the back is fully on. Any ideas??

Also since you know a lot about this electrical stuff can you enlighten me about a fuse box question I have. I checked all the fuses with the trouble light. When the ignition switch is off, the bottom two fuses (10 Amp) show power on both sides of the fuse. When I turn the ignition on the bottom 2 and the top 3 fuses (15, 10 &3) show power on both sides. The third one up from the bottom does not show any power key on or key off. Why is that? I want to thank you very much for you help with this. You saved me many hours of frustration. Mark
Check the driver's side courtesy bulb and be sure it's the correct bulb. It MUST be a double contact bulb (the base is not grounded as in most of the other bulbs. 90 is the correct number. In fact check all three. Both under dash courtesy bulbs and the one in the rear are 90's and MUST be double contact. If you have the common single contact bulb in there it will short your courtesy circuit to ground and blow a fuse. Because the ground is made by opening one of the doors or turning on the courtesy lamps with the headlight switch, those wires will read 12v anytime the battery is connected. Only when the ground is made will the voltage on the white wire drop to zero.
On the fuses, the third fuse up is the instrument lamp fuse, it won't have any voltage unless you have the headlight switch in park or on and the dimmer rotated to light up the inst. The voltage will vary with the position of the dimmer in the headlight switch rotation. I'm pretty sure the bottom fuse (brake and courtesy) is supposed to be a 20a fuse, but check your manual or look at the printing on the fuse panel.
EDIT: I just looked, my stop/courtesy is a 15A

Last edited by 65GGvert; 02-09-2019 at 08:07 PM.
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Old 02-09-2019, 10:21 PM
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65GGvert, thank you for the information on the type of bulbs. I will check all and let you know what I find. Will also look for the Amps marked on the fuse panel. Again, thank you for your help. Mark
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Old 02-11-2019, 02:49 PM
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65GGvert, here is an update based on the Feb 9 information you provided. I looked at the fuse panel and it is a 15A fuse. I removed the 3courtesy bulbs. All three are double contact bulbs, however, one is a GE90, one is a GE100, and the last one I don’t know what it is. Looks like a bulb for the tail lights as it has double filaments. Today I will try and find a few more GE90’s.

I think I may have found the problem with the courtesy lights though. While studying the light switch to see if I could see anything wrong with it, I remembered that the panel is not grounded, therefore, the light switch was not grounded (I assumed that it should be). When I installed the Dakota Digital instruments there was no place to put the ground so I didn’t. Yesterday I grounded the light switch and plugged in the wire connector to see if it made a difference. Everything worked as they should. Door open-all lights come on. Door closed- all lights go off (the rear light use to stay on). Doors closed and turn the switch **** all the way counter clockwise and all lights come on. Turn it back clockwise and everything shuts off.

I wanted to see if there was any voltage on the white wire in the switch connector under various conditions (the switch is grounded):

-doors closed and no lights on – 12.5/V on white wire

- doors closed, switch **** turned clockwise - all lights on - .19V on white wire

-door open, all lights on - .078V on white wire

Do these voltage numbers look right? I do not really understand the voltage and why there would be a very little amount on the wire, but I assume everything is OK in that area. If not, please let me know.

I want to thank you very much for your help. I never would have found the problems without your help. Mark
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