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87 Carerra, 3.2 liter en
 
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Help: No volt Power

Everyone:

I have been working with my fuse panel in the front of the car and I have 12 volt constant power (whether the ignition is on or off) where I am supposed to have it. The fuse wires that are supposed to receive constant 12 volt power directly from the battery are getting it.

However, for the fuse sources that are supposed to get 12 volt power when the ignition is turned on (switched on power) are not getting any power. I mean absolutely none of the fuses that rely on switched on power are working they are all dead. Also, there is no 12 volt power going to the back of the car, like the coil is not hot or powered when the ignition is turned on.

Can someone direct me as to where I might look to see why my switched on 12 volt power is not going to the front fuse panel or to the back of the car. Is this 12 volt power initiated by a wire at the starter or something that sends 12 volts to the brain or throughout.

Please help as I am at a loss
Old 08-28-2012, 05:58 AM
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Quote:
Originally Posted by Srwilliams View Post
Everyone:

I have been working with my fuse panel in the front of the car and I have 12 volt constant power (whether the ignition is on or off) where I am supposed to have it. The fuse wires that are supposed to receive constant 12 volt power directly from the battery are getting it.

However, for the fuse sources that are supposed to get 12 volt power when the ignition is turned on (switched on power) are not getting any power. I mean absolutely none of the fuses that rely on switched on power are working they are all dead. Also, there is no 12 volt power going to the back of the car, like the coil is not hot or powered when the ignition is turned on.

Can someone direct me as to where I might look to see why my switched on 12 volt power is not going to the front fuse panel or to the back of the car. Is this 12 volt power initiated by a wire at the starter or something that sends 12 volts to the brain or throughout.

Please help as I am at a loss
Check at the ignition switch itself. Look behind the switch and you will see a plug connector. Pull the plug connector out slightly so the pins from the switch are exposed and connect you meter (or test light) to the appropriate pin to determine if power is going through the switch to the wires in the plug when the switch is turned to "on."
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Old 08-28-2012, 06:22 AM
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87 Carerra, 3.2 liter en
 
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Quote:
Originally Posted by ossiblue View Post
Check at the ignition switch itself. Look behind the switch and you will see a plug connector. Pull the plug connector out slightly so the pins from the switch are exposed and connect you meter (or test light) to the appropriate pin to determine if power is going through the switch to the wires in the plug when the switch is turned to "on."
Thanks Ossie:

That will be my start point. If I check the pin and there is no 12 volt power going thru the switch where should I trouble shoot from there (I am asking so when I go to the car and find out that is the problem, I would like to know where to go from there).

Last edited by Srwilliams; 08-28-2012 at 07:04 AM..
Old 08-28-2012, 06:30 AM
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Ignition switch fix--mechanical
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Old 08-28-2012, 07:08 AM
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87 Carerra, 3.2 liter en
 
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Thanks Sully
Old 08-28-2012, 07:45 AM
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The link posted refers to a mechanical fix if that is necessary. You should have a clue if you feel no resistance in turning the key to the "start" position. If you still feel the spring resistance and the key pops back from "start" to "run", then the mechanical part is probably ok. Try this test first.

The part of the switch that usually fails is the electrical component--easily replaceable once the ignition switch is removed from the dash. If the mechanical switch is turning the electrical portion, you should be getting power readings from the different terminals as you rotate the key in the switch. If you don't, and the mechanical part is good, replace the electrical piece.
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Old 08-28-2012, 09:09 AM
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Wiring connections........

Quote:
Originally Posted by Srwilliams View Post
Everyone:

I have been working with my fuse panel in the front of the car and I have 12 volt constant power (whether the ignition is on or off) where I am supposed to have it. The fuse wires that are supposed to receive constant 12 volt power directly from the battery are getting it.

However, for the fuse sources that are supposed to get 12 volt power when the ignition is turned on (switched on power) are not getting any power. I mean absolutely none of the fuses that rely on switched on power are working they are all dead. Also, there is no 12 volt power going to the back of the car, like the coil is not hot or powered when the ignition is turned on.

Can someone direct me as to where I might look to see why my switched on 12 volt power is not going to the front fuse panel or to the back of the car. Is this 12 volt power initiated by a wire at the starter or something that sends 12 volts to the brain or throughout.

Please help as I am at a loss

SRWilliams,

What year/model is your car? Do you have a wiring diagram specific to your car? I have replaced the front and rear fuse panels of a '78SC and found using a test light or a continuity tester very helpful in tracing the lines (wires). It is time consuming and requires complete focus on your work in solving your problem. Do you have the ignition and light switches pulled out from the dash? From the battery, start checking the power source/s before and after the ignition switch. The rear (engine bay) gets a direct power (red wire) from the battery. BTW, several circuits (front fuse panel) get direct power too from the battery and this would help you locate where the 'break' occurs. Keep us posted.

Tony

Last edited by boyt911sc; 08-29-2012 at 07:55 AM..
Old 08-28-2012, 08:14 PM
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Quote:
Originally Posted by boyt911sc View Post
SRWilliams,

and found using a timing light or a continuity tester very helpful in tracing the lines (wires).
Tony are you meaning test light here vs timing light?
Old 08-29-2012, 05:44 AM
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From your profile it looks like an '87. Power to the ignition switch is pin 30 red. Check there to see if the power from the battery is going to the ignition switch.
On all the 911's the run power is from pin 15 red/black on the ignition switch and starter is pin 50 yellow.
Ignition coil is also from pin 15.
One thing you may want to look at also is the anti theft system is not causing issues.
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Old 08-29-2012, 06:46 AM
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+1 on the anti-theft device.
The aftermarket installer who put the one in that I subsequently removed had cut and spliced in his wiring (the red/black lead) approximately 10mm outside the ignition switch, which made it all the more difficult to correct. Chances are that the run power is routed through a defective alarm system module. Great call, Ed!
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Old 08-29-2012, 07:50 AM
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Correction......

Quote:
Originally Posted by Bob Kontak View Post
Tony are you meaning test light here vs timing light?
Thanks for catching the mistake. It should be test light not timing light.

Tony
Old 08-29-2012, 07:56 AM
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+1 on the anti-theft device.
Mine gave me fits before I pulled it out ten years ago.
Old 08-29-2012, 08:38 AM
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thanks to everyone fpr your help and guidance.

I have a 1987 cabriolet 3.2 liter.

Well, I am making progress. Before I thought I had no 12 volts at the coil, but that is not true. I checked the coil to the back and I am getting 12 volts across the coil and so that is hot. So that means I am getting 12 volts coming from the ignition I believe. I am also getting constant 12 volts at the fuse panel for the wires that require constant power.

But what is perplexing me is that for all of the accessories that rely on the fuse panel that get 12 volts when the car is on I am not getting 12 volts. I got 12 volts on the constant fuse wires. But for the power wires that are supposed to switch on (Window wipers, blowers, etc) when the car is turned on, I am not getting 12 volts.

Any suggestions as to why I am not getting swutched on power at the fuse panel
Old 08-30-2012, 01:40 PM
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87 Carerra, 3.2 liter en
 
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thanks to everyone fpr your help and guidance.

I have a 1987 cabriolet 3.2 liter.

Well, I am making progress. Before I thought I had no 12 volts at the coil, but that is not true. I checked the coil to the back and I am getting 12 volts across the coil and so that is hot. So that means I am getting 12 volts coming from the ignition I believe. I am also getting constant 12 volts at the fuse panel for the wires that require constant power.

But what is perplexing me is that for all of the accessories that rely on the fuse panel that get 12 volts when the car is on I am not getting 12 volts. I got 12 volts on the constant fuse wires. But for the power wires that are supposed to switch on (Window wipers, blowers, etc) when the car is turned on, I am not getting 12 volts.

Any suggestions as to why I am not getting switched on power at the fuse panel
Old 08-30-2012, 01:41 PM
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Quote:
Originally Posted by Srwilliams View Post
Any suggestions as to why I am not getting switched on power at the fuse panel
Maybe you could try the tests mentioned above regarding your ignition switch.
Old 08-30-2012, 01:46 PM
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Need a little information. Does the starter spin when you turn the key on? Does the radio work? With the key on do you get power to the red/black wire on fuse 7? You say you have power to the coil. Do you get 12v from the black wire to chassis ground?
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Old 08-31-2012, 03:25 AM
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Srwilliams, here's a little blurb to consider if you don't know it already: many of the fuses in the panel do not have any voltage present at all UNLESS the switch which operates the fused device, lamp, or whatever is switched on. An illustration of this is the turn signal fuse. It is effectively an inline fuse despite the fact that it's located in the central fuse panel. It gets it's feed via the flasher unit, the stalk switch and points upstream leading eventually back to the battery. You'll find that a lot of them are wired like that, no juice standing on them.
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Old 08-31-2012, 08:55 AM
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Verify power from X & 15 terminals.........

Charles,

Check that these terminals (wires) have power when you turned the IS (ignition switch) to ON position. The red/black wire @15 (IS) goes to S7 (panel #1), the red/yellow wire @ X goes to S4, S5, S6 (panel #1), and the red/white wire @ X goes to the head light switch.

The red wire from IS @30 goes to head light SW @30......and so on. The head light switch and few other switches control the power supply to several fuses (7 or 8) if I remember correctly.

Please note that I am using the Bentley manual fuse numbering. Add +3 to convert to factory configuration. Keep us posted.

Tony
Old 08-31-2012, 11:21 AM
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Bentley Carrera manual.........

Charles,

The electrical circuits for the 8 fuses for panel #2 are in the following pages (Bentley):

Fuses 1/2/3/4..........page 970-72
Fuses 5/6/7.............page 970-66
Fuses 8...................page 970-70

Keep us posted.

Tony
Old 08-31-2012, 09:44 PM
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