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Discussion Starter #1
mk9 2.2idtec alarm went off at night unlock and locked it.3am went off again struggled to turn off wouldn't relock,went out later started ok then all the warning lights came on traction control,boot open,doors open steering fail,tyre pressures,engine management,scanned it p0504 powertrain,checked braklight switch fine,cleared code ,engine management light still on rest cleared ,went 3 miles all lights back on ,scanned again p0504powertrainscanned all units no faults,if I try lock it on remote sometimes it locks but goes off after a couple of minuites,if I lock with key it locks but indicators start to flash ,it will still unlock with key and drives fine any ideas thanks before I burn it
 

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The first question with electrical problems is always how old the battery is.
 

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Are you sure he's talking about an aftermarket alarm? I was wondering if it could be aftermarket, but if I'm reading his post correctly, he could very well be describing symptoms of the factory alarm. But I also agree with checking the battery. Put a digital voltmeter on it when these symptoms are occurring, without starting the car, and see what the voltage is. I know a low-voltage battery can cause crazy things to happen with an aftermarket alarm. I would think it could also affect the factory one, as well.
 

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Discussion Starter #6
the battery is new from honda 3 months ago and fitted by them,voltage checked in morning 12.33,and this wouldn't cause all the warning lights to be on when the car is running,with 14.1 volts ,the alarm is factory,it has been scanned 3 times and p0504 powertrain is the only code,the brake light switch has been replaced,it has been raining for a few days and this has never happened before it stopped raining yesterday and now after a few hours all but one of the faults have gone ,which is boot open this only comes on when I set off from a standstill,ive checked everwhere and there is no water in the car anywhere in the boot or engine bay,the ecu plugs have been checked and are dry and clean, is there a common earth fault maybe,the car has done 54000 miles,its not the alarm that's the main thing its the fact that all the warning lights were on but the car ran fine
 

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I'm guessing the "mk9" means mark 9, or 9th generation?

The only thing that comes to mind about all the warning lights coming on is that, typically, when you turn on the key of most cars without starting the engine, all the warning lights come on so you can see that the bulbs/LED's are working. This is pure speculation, but maybe something in the car is tripping this circuit/condition even after the car is running? Maybe something in the ignition switch? Again, just guessing here.
 

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Discussion Starter #14
I have checked all plugs and no water in the ecu or fusebox,there are no signs of water anywhere in the car on the carpets or any water marks on the inside bodywork,it cleared for 3 days then just started again all the warning lights are on the boot lock is locking and unlocking constantly and the brakelights are dim and flickering all the time,its been scanned and no faults show up,im putting it down to a corrupt fusebox or ecu ,but the car runs fine
 

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Well at this point the easy thing to do is troubleshoot the brake light problem.
It's a basic circuit and if you find the problem with the brake lights, you'll likely solve the other problems along the way.

I'm surprised the person that "scanned" for codes didn't begin checking why the brake lights are acting weird.
 

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Discussion Starter #16
no problem with brake lights or boot lock at the time of the scans ,at the moment the boot is constantly unlocking itself about every 10 to 15 seconds if I start the car the door warning is on but goes of if I press the throttle pedal,engine management is on constantly ,and the brake lights are flickering and sometimes flash on when parked up but work fine when running
 

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no problem with brake lights or boot lock at the time of the scans ,at the moment the boot is constantly unlocking itself about every 10 to 15 seconds if I start the car the door warning is on but goes of if I press the throttle pedal,engine management is on constantly ,and the brake lights are flickering and sometimes flash on when parked up but work fine when running
Understood.
What I'm saying is troubleshoot the problem that you can duplicate all the time. All this could be from a faulty earth ground, would not hurt to check under the hood for loose or corroded grounding terminals.

Also, has your car been wrecked or had any recent repairs?
 

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I am no mechanic, and I don't know if anyone has already tried this, but I Googled "Civic UK P0504" and came up with this site...

OBDII PorwerTrain P Codes - United Kingdom | BBA Reman

If you scroll down, it lists P0504 as "P0504 Brake Switch A/B Correlation". This would seem to make sense considering the brake light issues.

This may be generic information and may not be related directly to the Civic, and again, I have no idea how accurate any of this may be, but I figured I'd throw this out there.

I will also point out that, on my previous car, a 2002 Ford Escort ZX2, I started having trouble with the cruise control not working and the automatic transmission not going into "lock-up" for the torque converter on the highway. Thinking I was looking at an expensive sensor or computer type repair, I checked out the ZX2 based forum I was a member of, and I found that -- of all things -- a burned out bulb for the third (center) brake light could cause these issues. Buying a $2 bulb and replacing that burned out bulb solved the issues. Something about some sort of ground or signal that passes through the filament of the bulb. Of course, I'm not saying that's what's going on here, but with these computer-controlled cars, sometimes weird things have unexpected causes.
 

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I am no mechanic, and I don't know if anyone has already tried this, but I Googled "Civic UK P0504" and came up with this site...

OBDII PorwerTrain P Codes - United Kingdom | BBA Reman

If you scroll down, it lists P0504 as "P0504 Brake Switch A/B Correlation". This would seem to make sense considering the brake light issues.

This may be generic information and may not be related directly to the Civic, and again, I have no idea how accurate any of this may be, but I figured I'd throw this out there.
Good find.

Maybe you should consider a career as an auto mechanic...
 

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Discussion Starter #20
I did google the p code ,and joined many honda forums but no one had the same symptoms I replaced the brake light switch as the first step as that was the p0504 description,i disconnected the wiring plugs in the boot lid starting with the brake lights but the fault was still there,i then disconnected all the other plugs and all the warning lights apart from the engine management went off and the car is fine,i have since reconnected the plugs and all faults have cleared and the car is back to normal,now I have a fuse box I haven't used,maybe it will happen again,thanks for your help
 
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