it now wont lock and the brake lights are flickering constantly without the keys in the car
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
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.
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
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?
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.
Last edited by NightFlyer; 10-24-2019 at 11:39 AM.
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