# display goes black when applying brake



## SLIDER (6 mo ago)

Wondering if anyone has seen this behavior ( 



 ) when applying the brake the display goes black, this is a 2018 model s ( out of warranty ).


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## Ed Woodrick (May 26, 2018)

I'd tend to call this display flashes, with your description I was expecting the screen to go black and stay that way.
Has this been happening through multiple updates or just the current one? Which one are you on?
Have you checked the 12V battery voltage? Have you watched it as the brakes turned on?
This seems to have been filmed at night, when your 12V draw is often at its highest, does it happen during the daytime as well?

I've only got a Model 3 and a Model Y, so I don't have the speedometer display, so no input from me.


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## SLIDER (6 mo ago)

It’s filmed in a parking garage- after reset it’s seems ok but it comes back at some point, seems to be occurring also when driving with the lights on for some reason….


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## SLIDER (6 mo ago)

SLIDER said:


> It’s filmed in a parking garage- after reset it’s seems ok but it comes back at some point, seems to be occurring also when driving with the lights on for some reason….


And it happens with all updates


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## Ed Woodrick (May 26, 2018)

SLIDER said:


> It’s filmed in a parking garage- after reset it’s seems ok but it comes back at some point, seems to be occurring also when driving with the lights on for some reason….


That's why I suggest checking 12V battery voltage, when lights are on, that's when the most current is being drawn and maybe causing a significant drop in voltage. It then seems as if this display board or maybe even just the backlight doesn't like the voltage drop.


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## SLIDER (6 mo ago)

I understand and thanks for your answer Ed, i did a reset on the steeringwheel and now it seems stable again, but i keep monitoring it what i understand is that the 12v battery only does the startup of the systems like (lights?) are they still depended on this after they are on ?


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## garsh (Apr 4, 2016)

I'd never seen that before.

So this is only happening (temporarily) to the left display. And it doesn't appear to be a computer reboot, since the display comes back immediately after braking.

That looks like some kind of loose connector for that display. Either try to locate & check connections yourself, or take it to a service center (even though it's out of warranty).


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## SLIDER (6 mo ago)

Great - was actucally thinking about doing this, is there a manual how this can be removed/opend to check for the connections? Is it needed to disconnect the HV power & 12v ?


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## garsh (Apr 4, 2016)

SLIDER said:


> Great - was actucally thinking about doing this, is there a manual how this can be removed/opend to check for the connections? Is it needed to disconnect the HV power & 12v ?


After logging into your account, I think you can access service manuals here:






Tesla Service







service.tesla.com





But that may be U.S.-specific. Let me know if it works for you.


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## SLIDER (6 mo ago)

i dont see anything no possbile to make a dump?


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## Ed Woodrick (May 26, 2018)

SLIDER said:


> I understand and thanks for your answer Ed, i did a reset on the steeringwheel and now it seems stable again, but i keep monitoring it what i understand is that the 12v battery only does the startup of the systems like (lights?) are they still depended on this after they are on ?


The 12V system runs effectively EVERYTHING in the car except for the motors and AC. But even then, the 12V runs the systems that turn those on. The big battery periodically recharges the 12V battery. So at night with the headlights on, you are probably at max draw on the battery.
the 12V batteries don't last forever expect to replace about every 3 years.


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## SLIDER (6 mo ago)

Gotcha well i guess its a appointment with tesla then, this morning when driving i did a reset on the displays but it came straight back, i noticed that when the car brakes the display doesnt go offline but when i use the peddle it does, @Ed i guess there is no way to install a 12v battery yourself and your forced to go to Tesla?


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## Ed Woodrick (May 26, 2018)

You absolutely can install a 12V battery, it's under the hood. There are a number of threads talking about people doing it. You local auto parts should be able to do some testing on it.


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## FRC (Aug 4, 2018)

Ed Woodrick said:


> You absolutely can install a 12V battery, it's under the hood. There are a number of threads talking about people doing it. You local auto parts should be able to do some testing on it.


The problem is that an appropriate battery from the auto parts store costs about double what Tesla mobile will charge installed.


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## SLIDER (6 mo ago)

update - replaced the battery with an oohmi battery last week but it still happend although not so frequent, second what i did now is to clean all mounted ground wires there was some rust on some connected bolts - keep you posted on the progress.


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## SLIDER (6 mo ago)

update dec 2022 - removed tail lights and reseated them - no change same issue.


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## JasonF (Oct 26, 2018)

SLIDER said:


> update - replaced the battery with an oohmi battery last week but it still happend although not so frequent, second what i did now is to clean all mounted ground wires there was some rust on some connected bolts - keep you posted on the progress.


This might be a clue. Try giving either the brake light switch or the cluster an isolated new ground to something metal on the car body, and see if that fixes it. You don't even have to cut the ground and replace it right away just to test - you can shove a pin into the ground side of the connector and alligator clip it to a wire leading to a frame piece (obviously verify continuity if you do that).


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## SLIDER (6 mo ago)

JasonF said:


> This might be a clue. Try giving either the brake light switch or the cluster an isolated new ground to something metal on the car body, and see if that fixes it. You don't even have to cut the ground and replace it right away just to test - you can shove a pin into the ground side of the connector and alligator clip it to a wire leading to a frame piece (obviously verify continuity if you do that).


OK will do this - do you know which wire on the brake switch is ground?


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## JasonF (Oct 26, 2018)

SLIDER said:


> OK will do this - do you know which wire on the brake switch is ground?


No, but it’s easy enough to find out - it will be the one without 12 volts measured between the wire and something metal.


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## SLIDER (6 mo ago)

Hmmz there are 4 wires on the connector 2 have 12v 2 haven't before i play russian roulette is there anyone who has the pinlayout for partnumber 1005124-00-A ( brake pedal switch )? please before i lose my mind.


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## JasonF (Oct 26, 2018)

Ok now that you know which ones are power, you can disconnect the switch from the wiring and test power pin to each one of the others with the switch pressed and with it not pressed. If you get continuity on one pair of pins, those are the two that are closed by the switch and turn on the brake light. By process of elimination, the one remaining wire that isn't part of that switch circuit and doesn't have voltage would either be an independent ground or CANbus.

Though at this point since it's 4 wires and possibly CANbus connected (CANbus is highly resistance sensitive), and the switch only costs $40-$50, it might be worth it just to replace the switch and see what happens. That gives you a 50% chance of solving it for not much money!


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## SLIDER (6 mo ago)

Hi Jason thanks for your fast reply, i actually did already replace the switch  and this didnt change unfortunaly - but i do think its an grounding issue so i reallly would like to try this.


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## JasonF (Oct 26, 2018)

SLIDER said:


> Hi Jason thanks for your fast reply, i actually did already replace the switch  and this didnt change unfortunaly - but i do think its an grounding issue so i reallly would like to try this.


Darn...the next step then is testing wires that do not have 12 V for continuity to ground - aka the metal structure of the car. Since CANbus may be involved, it's going to expand the search footprint a bit, since VCFront/VCLeft might be involved as well.

EDIT: Another thing I forgot is the brake booster is electric as well, I believe 12 volt, and since it's a motor it probably uses quite a few amps. It's possible that the ground fault is on the other side of the firewall with the brake booster. And it's a large scale suspect because it draws enough amps to cause the voltage to drop enough to make the display reboot, especially if it has a ground fault.


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## SLIDER (6 mo ago)

Ok can you point me into the direction where it is under the frunk


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## JasonF (Oct 26, 2018)

SLIDER said:


> Ok can you point me into the direction where it is under the frunk


I'm not sure, but it's going to be on the firewall and look something like this:









14-16 TESLA MODEL S IBOOSTER ELECTROMECHANICAL BRAKE BOOSTER W/AUTOPILOT | eBay


Find many great new & used options and get the best deals for 14-16 TESLA MODEL S IBOOSTER ELECTROMECHANICAL BRAKE BOOSTER W/AUTOPILOT at the best online prices at eBay! Free shipping for many products!



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## SLIDER (6 mo ago)

Yes I found it online is it normal for the 2 wire connection to be 1 positive and one GND?


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## JasonF (Oct 26, 2018)

SLIDER said:


> Yes I found it online is it normal for the 2 wire connection to be 1 positive and one GND?


All DC powered connections have at least 1 +V and one GND.


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## SLIDER (6 mo ago)

Ok 😇


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