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> Troubleshooting my electrical issues., My first problem was blinking red light on the dash for brakes
vin man
post Feb 11 2017, 06:08 PM
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Edit: Renamed the thread because what started out as one electrical problem has led to others and I'm hoping to capture all the information in this one thread.

Initial Problem:

When I turn on the 72, the red light on the dash (in the top part of the gauge on the left side of the dash) blinks and won't stop. I've made sure the e-brake is all the way off. I'm wondering where is the switch that controls this light?

I've read that when the brake master cylinder is replaced, there is a switch on the MC that needs to be reset. I used a MC from Rock Auto and there is not reset switch button. Only the electrical switch that activates the brake lights.

I have a brown wire that is connected to nothing in the area of the e-brake handle. I've tried grounding it but the light still blinks on the dash.

Any advice would be appreciated.


Click here for video of the blinking light: Blinking red light

(IMG:http://www.914world.com/bbs2/uploads_offsite/i304.photobucket.com-11380-1486858110.1.jpg)

Master cylinder:
(IMG:http://www.914world.com/bbs2/uploads_offsite/i304.photobucket.com-11380-1486858537.1.jpg)
(IMG:http://www.914world.com/bbs2/uploads_offsite/i304.photobucket.com-11380-1486858538.2.jpg)
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Spoke
post Feb 11 2017, 10:32 PM
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The brake warning light will flash if the brown wire by the e-brake is grounded. Also if the switch on the MC is closed. Try disconnecting the wires on the MC switch and the e-brake wire is not grounded. This should cause the flashing light to stop.
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vin man
post Feb 11 2017, 10:43 PM
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QUOTE(Spoke @ Feb 11 2017, 09:32 PM) *

The brake warning light will flash if the brown wire by the e-brake is grounded. Also if the switch on the MC is closed. Try disconnecting the wires on the MC switch and the e-brake wire is not grounded. This should cause the flashing light to stop.



The wire is currently not connected to anything so not grounded. I will pull the wires off the switch on MC. If I do pull those wires and the light stops flashing, do I lose any other functionality by not having them connected to the switch on the MC?
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vin man
post Feb 11 2017, 10:45 PM
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I've been doing some more research and did find a thread that had a picture in it and I spotted the switch. I circled it in this version of the photo:

(IMG:http://www.914world.com/bbs2/uploads_offsite/i304.photobucket.com-11380-1486874715.1.png)

Will also try disconnecting the switch on the MC.

Thanks to this thread for the help: Parking Brake Handle removal thread
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AlanB
post Feb 12 2017, 08:01 AM
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Wow, talk about the right post at the right time. I just replaced my ignition lock and the big red light started blinking when I turned the car on. I was ready to start going through all the steering wheel connections when I saw this post. I'm a newbe and I never thought of the parking brake. THANK YOU for saving me some really frustrating time.

One maybe useful suggestion. The brown wire is pretty thin and could be easy to break. Mine's now under a thin strip of duct tape to make it more obvious and to give it some protection.
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vin man
post Feb 12 2017, 11:46 AM
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QUOTE(Spoke @ Feb 11 2017, 09:32 PM) *

The brake warning light will flash if the brown wire by the e-brake is grounded. Also if the switch on the MC is closed. Try disconnecting the wires on the MC switch and the e-brake wire is not grounded. This should cause the flashing light to stop.



I took the wires off the MC and the wire off the switch at the handbrake. The light still flashes on the dash.
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rgalla9146
post Feb 12 2017, 12:23 PM
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QUOTE(vin man @ Feb 12 2017, 12:46 PM) *

QUOTE(Spoke @ Feb 11 2017, 09:32 PM) *

The brake warning light will flash if the brown wire by the e-brake is grounded. Also if the switch on the MC is closed. Try disconnecting the wires on the MC switch and the e-brake wire is not grounded. This should cause the flashing light to stop.



I took the wires off the MC and the wire off the switch at the handbrake. The light still flashes on the dash.


Find the wire at the hand brake switch and disconnect it.
Follow it out of the seat crossmember and wherever it goes to
be sure it is not making contact with anything that could ground it.
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vin man
post Feb 12 2017, 01:31 PM
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QUOTE(rgalla9146 @ Feb 12 2017, 11:23 AM) *

QUOTE(vin man @ Feb 12 2017, 12:46 PM) *

QUOTE(Spoke @ Feb 11 2017, 09:32 PM) *

The brake warning light will flash if the brown wire by the e-brake is grounded. Also if the switch on the MC is closed. Try disconnecting the wires on the MC switch and the e-brake wire is not grounded. This should cause the flashing light to stop.



I took the wires off the MC and the wire off the switch at the handbrake. The light still flashes on the dash.


Find the wire at the hand brake switch and disconnect it.
Follow it out of the seat crossmember and wherever it goes to
be sure it is not making contact with anything that could ground it.


OK, thanks. I've got family stuff do do today so no more working on the car till tomorrow night after work at the earliest. Will keep going on the electrical debugging at the shop asap!

FYI - I did pull the relay that was causing the flashing. While the red light did go off and stop blinking, the turn signals also stopped working. Apparently, they share a relay. (IMG:style_emoticons/default/biggrin.gif) I put the relay back as turn signals are important.
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Spoke
post Feb 12 2017, 01:58 PM
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You can pull the bulb out to stop the flashing.
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vin man
post Feb 12 2017, 03:45 PM
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QUOTE(Spoke @ Feb 12 2017, 12:58 PM) *

You can pull the bulb out to stop the flashing.
will I still hear the clicking of relay?
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Spoke
post Feb 12 2017, 05:03 PM
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QUOTE(vin man @ Feb 12 2017, 04:45 PM) *

QUOTE(Spoke @ Feb 12 2017, 12:58 PM) *

You can pull the bulb out to stop the flashing.
will I still hear the clicking of relay?

The relay will stop flashing when the bulb is removed. See the turnsignal/brake warning schematic below. one of the wires from either the MC switch or the e-brake switch is shorting to chassis. Removing the bulb will break the circuit and the flasher relay will not operate.

This isn't a fix of course because somewhere the wire to the MC switch or e-brake is grounded. When you fix the grounded wire, you can put the bulb back in.

My guess is the brown wire to the e-brake is touching the chassis under the seat or throughout its run to the bulb.


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vin man
post Feb 12 2017, 05:25 PM
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QUOTE(Spoke @ Feb 12 2017, 04:03 PM) *

QUOTE(vin man @ Feb 12 2017, 04:45 PM) *

QUOTE(Spoke @ Feb 12 2017, 12:58 PM) *

You can pull the bulb out to stop the flashing.
will I still hear the clicking of relay?

The relay will stop flashing when the bulb is removed. See the turnsignal/brake warning schematic below. one of the wires from either the MC switch or the e-brake switch is shorting to chassis. Removing the bulb will break the circuit and the flasher relay will not operate.

This isn't a fix of course because somewhere the wire to the MC switch or e-brake is grounded. When you fix the grounded wire, you can put the bulb back in.

My guess is the brown wire to the e-brake is touching the chassis under the seat or throughout its run to the bulb.


If I do as suggested and remove the bulb, breaking the circuit of the flasher relay - will my turn signals still work? I removed the relay and the turn signals did not work.

I want to fix it properly and find the short, but in the interim, I don't mind pulling the bulb provided I will still have turn signal functionality.

Unfortunately, when it comes to electrical diagrams, I don't comprendo well.
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Rand
post Feb 12 2017, 05:44 PM
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Isn't there a reset button on the master cylinder? Push while ebrake released. Sounds like something else may be afoot here, but seems like worth a try.
EDIT: Never mind. I see you looked for that but it doesn't have one?
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vin man
post Feb 12 2017, 05:59 PM
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QUOTE(Rand @ Feb 12 2017, 04:44 PM) *

Isn't there a reset button on the master cylinder? Push while ebrake released. Sounds like something else may be afoot here, but seems like worth a try.
EDIT: Never mind. I see you looked for that but it doesn't have one?



Doesn't have one.
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ndfrigi
post Feb 12 2017, 06:09 PM
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i did remove the bulb from the gauge 4 yrs ago. no effect with my turn signal, emergency light works too.
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vin man
post Feb 12 2017, 06:15 PM
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QUOTE(ndfrigi @ Feb 12 2017, 05:09 PM) *

i did remove the bulb from the gauge 4 yrs ago. no effect with my turn signal, emergency light works too.



Thanks for that info. I'm going to try and disconnect/replace the switch under the handbrake. If that doesn't fix the problem, I will pull the bulb.
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Spoke
post Feb 12 2017, 06:51 PM
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QUOTE(vin man @ Feb 12 2017, 06:25 PM) *
If I do as suggested and remove the bulb, breaking the circuit of the flasher relay - will my turn signals still work?


Removing the bulb will not affect the turnsignals. Porsche designers had the bright idea to double use the flasher for turnsignals and to flash the brake warning light.

I thought in the first pic the wire to the e-brake switch was disconnected.
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vin man
post Feb 12 2017, 09:47 PM
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QUOTE(Spoke @ Feb 12 2017, 05:51 PM) *

QUOTE(vin man @ Feb 12 2017, 06:25 PM) *
If I do as suggested and remove the bulb, breaking the circuit of the flasher relay - will my turn signals still work?


Removing the bulb will not affect the turnsignals. Porsche designers had the bright idea to double use the flasher for turnsignals and to flash the brake warning light.

I thought in the first pic the wire to the e-brake switch was disconnected.


There is a brown wire with white tracer that is disconnected in the area of the e-brake. But I'm not sure if this is the wire that goes to the e-brake switch. I suspect it is since the same color wire is one of the 2 wires on the master cylinder. But I have not yet verified. I was thinking - since that wire is disconnected and the light still blinking, maybe it is not the e-brake wire, but instead a seat belt sensor wire?

I hope to identify the switch tomorrow eve and confirm that a wire is on it.
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vin man
post Feb 13 2017, 05:18 PM
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QUOTE(vin man @ Feb 12 2017, 08:47 PM) *

QUOTE(Spoke @ Feb 12 2017, 05:51 PM) *

QUOTE(vin man @ Feb 12 2017, 06:25 PM) *
If I do as suggested and remove the bulb, breaking the circuit of the flasher relay - will my turn signals still work?


Removing the bulb will not affect the turnsignals. Porsche designers had the bright idea to double use the flasher for turnsignals and to flash the brake warning light.

I thought in the first pic the wire to the e-brake switch was disconnected.


There is a brown wire with white tracer that is disconnected in the area of the e-brake. But I'm not sure if this is the wire that goes to the e-brake switch. I suspect it is since the same color wire is one of the 2 wires on the master cylinder. But I have not yet verified. I was thinking - since that wire is disconnected and the light still blinking, maybe it is not the e-brake wire, but instead a seat belt sensor wire?

I hope to identify the switch tomorrow eve and confirm that a wire is on it.


#1 - pulling the bulb is not the answer. While I no longer get a flashing light on the dash, the flasher relay does make a noise. It flashes much faster - almost sounding like a fuel pump.

#2. There is no switch anyplace near the hand brake that I can find.

(IMG:http://www.914world.com/bbs2/uploads_offsite/i304.photobucket.com-11380-1487027916.1.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/i304.photobucket.com-11380-1487027916.2.jpg)

That experiment also didn't work out for the relay. It smoked. Now I need to see if I can find a new one.

Edit: This is the start of problem number 2 - no turn signals or any systems using the flasher.
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ndfrigi
post Feb 13 2017, 05:24 PM
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or maybe the noise is for the door when it is open there will be sound or for me it is a noice.
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