Black wire to nowhere.

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Old Jun 7, 2015 | 06:41 PM
  #1  
brownalteza's Avatar
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Question Black wire to nowhere.

Okay, Help. 1972 Cutlass, 350, with air. I have a black wire on the drivers side rear of the block. It blends in with the taped clump coming from the solenoid. It comes out of the taped bundle, going away from the solenoid, directly in back of the head. I have a 9 amp draw on my battery, I believe it is related to this wire. If it was to hook to the horn relay, it would have come out from the bundle closer to the firewall. It will light a test lamp, but very dim.
I have pulled all fuses to look for the draw on the battery, nothing changed.
The chassis electrical chart has one black wire going to the horn relay and though the firewall to the horn button. All items work, horn, lights, wipers and washers.
There is a second wire, on the chart, coming from the transmission. Trans control spark solenoid. I am not sure what this is.
Can anyone shed some light on what this wire may be and how to fix the short?
Old Jun 7, 2015 | 07:31 PM
  #2  
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Generally if a wire is not connected to anything there is no draw. The TCS allows the vacuum advance to work only in high gear and I believe reverse. Its an emissions thing, most people disable it.
Old Jun 7, 2015 | 08:45 PM
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I'm not the sharpest on electrical diagnoses. But after looking at the 71 wire diagram (same?) I have a few observations.

I think its great that you pulled the fuses to check draw. That makes me believe it forward of the firewall/cowl. 9 amps is quite a draw and that puzzles me.

Your post leads me to the circuits hot all the time.
Horn
Dome light and door switches.
Key buzzer
Is it bad? Hmm.

Have you pulled the black wire from the horn relay/key buzzer? Is the draw still there? That leads me to something called the "generator noise suppression condensor". could it be shorted internally? I don't know.

Previous owner modifications can be a problem. Stereos and added equipment etc. When a lot of folks see a black wire, they think they should ground it. I hope that is not your problem . ADDED- the transmisson controlled spark should not be a problem, unless some hack got in there.

Last edited by don71; Jun 7, 2015 at 08:47 PM. Reason: tcs should not effect this-see PO
Old Jun 7, 2015 | 08:53 PM
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I would just use a multimeter to see if there's power at this wire. If there is power, is it constant or switched.
Old Jun 8, 2015 | 07:39 AM
  #5  
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Originally Posted by brownalteza
Okay, Help. 1972 Cutlass, 350, with air. I have a black wire on the drivers side rear of the block. It blends in with the taped clump coming from the solenoid.
The factory harness does not use a black wire to the solenoid. The only wires to the solenoid are the large battery cable, the smaller red wire from the solenoid battery terminal to the threaded post on the horn relay, the purple wire from the NSS to the "S" terminal on the solenoid, and the yellow ignition bypass wire from the "R" terminal on the solenoid to the coil "+" terminal. If that's really a black wire (and not just black grease on the insulation) then it's not factory and you'll need to drop the starter and trace it.
Old Jun 11, 2015 | 06:27 PM
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brownalteza's Avatar
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So maybe I was not as clear as I could have been. The wire, and it is black, is in the bundle heading to the solenoid, coming from the firewall. The wire exits the bundle behind the head. All indications is it is a factory wire, the wires are wrapped with the correct tape and it looks vintage. I am thinking it does go to the TCS, but I haven't had time to track it down.
Thanks for your help and suggestions.
Old Jun 11, 2015 | 09:18 PM
  #7  
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Is it hot w/ the key in the IGN1 position or all the time? What type if ignition are you running?
Old Jun 12, 2015 | 08:36 AM
  #8  
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Originally Posted by brownalteza
So maybe I was not as clear as I could have been. The wire, and it is black, is in the bundle heading to the solenoid, coming from the firewall. The wire exits the bundle behind the head. All indications is it is a factory wire, the wires are wrapped with the correct tape and it looks vintage. I am thinking it does go to the TCS, but I haven't had time to track it down.
Thanks for your help and suggestions.
If it's really black with orange stripe, that's the kickdown wire for the TH400. The wire was included in every harness made, it was just taped up out of the way on cars with manual trans or TH350.
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