caseys Posted August 1, 2009 Share Posted August 1, 2009 Hi All, Well I've got the master warning light popping on and the dashboard Brake warning light. Only just started happening about 30 minutes ago. Checked all brake pads, discs all fine. Calipers seem fine too. No brakes are sticking, I can drive down the road in a straight line and it's not deviating. Checked brake fluid level and it's about 3mm away from the maximum fill level line (I'm thinking it may need more.. but please read on) Checked brake cylinder plugs, all look ok. Brake pedal feel is normal, brakes work as normally, no ABS light issue (it comes on at ignition then goes off as normal). Handbrake works fine as well. Pedal doesn't have any travel making me think that there's no leak. I can turn the engine on, take the handbrake off and master and brake light both go off. Put my foot on the brake pedal and both lights come back up and stay on even if I take my foot off the brake and will not go off until ignition is off. Turn back on, light's off when handbrake's off, press brake, occurs again. I've read many threads about the brake fluid level and it seemed to only occur to people at speed and then the light went off so wanted some opinions as it's staying on until engine switched off. I admit I haven't yet checked for stored error codes. I've got a bottle of 5.1 right here that I've just bought, it's Halfrauds bog standard stuff, is that OK to mix with Motul 5.1? Even if it's just a few millilitres? I haven't topped it up at all since I did a change of it about 20 months ago. Any advice? Quote Link to comment Share on other sites More sharing options...
Yaz Posted August 1, 2009 Share Posted August 1, 2009 I would top up the brake fluid and see if that changes it. I know of a common problem with high performance car is when you hit the throttle as speed, the power and force cause the handbrake to lift slighting, therefore causing the lights to light up, but that isn't what you are on about. It's a strange one. Might be the brake pedal sensor. When you say master warning light, do you mean the red light with exclamation mark in the speedo? Or the orange engine management light? Quote Link to comment Share on other sites More sharing options...
caseys Posted August 1, 2009 Author Share Posted August 1, 2009 Well gone out and topped up the fluid, line is now about 1mm above max fill line, it still did the same issue. The lights - Master warning light - the ! light in the rev gauge The brake light the (!) light in the fuel/temp gauge. No other lights being lit up. Guess I'll look for error codes? Tested it a few times, definitely happens after I put my foot on the brake pedal. I can hold down the pedal and after about 1-2 seconds the light comes on and stays on. Foot off the brake, put the handbrake up, but the handbrake down it's stuff on. Regarding resets of an ECU to make sure I've got no stored error codes before hand, I am running an emanage blue piggy back. Can these have their settings wiped if I remove the battery for a given period of time or are they retained in NVram? TIA Quote Link to comment Share on other sites More sharing options...
PhatB Posted August 1, 2009 Share Posted August 1, 2009 I would certainly go with brake fluid level first. Even slightly below the full line can cause this problem. I had the same problem on mine and even travelling at slower speeds the light would come up. Quote Link to comment Share on other sites More sharing options...
Homer Posted August 1, 2009 Share Posted August 1, 2009 Well gone out and topped up the fluid, line is now about 1mm above max fill line, it still did the same issue. The lights - Master warning light - the ! light in the rev gauge The brake light the (!) light in the fuel/temp gauge. No other lights being lit up. Guess I'll look for error codes? Tested it a few times, definitely happens after I put my foot on the brake pedal. I can hold down the pedal and after about 1-2 seconds the light comes on and stays on. Foot off the brake, put the handbrake up, but the handbrake down it's stuff on. Regarding resets of an ECU to make sure I've got no stored error codes before hand, I am running an emanage blue piggy back. Can these have their settings wiped if I remove the battery for a given period of time or are they retained in NVram? TIA Yep, check for error codes - to clear them remove the battery terminal for about 10 seconds. My money would be on the brake fluid level as the symptoms you describe are exactly what happens when it's low. The sensor is incredibly sesitive even when topped up to the max level, it needs to be filled to the very top of the max mark (even though you say it's above, which is confusing!) It may also be a problem with the hand brake sensor switch which again would cause the same, although you won't get an error code with that. Quote Link to comment Share on other sites More sharing options...
caseys Posted August 1, 2009 Author Share Posted August 1, 2009 Yep, check for error codes - to clear them remove the battery terminal for about 10 seconds. My money would be on the brake fluid level as the symptoms you describe are exactly what happens when it's low. The sensor is incredibly sesitive even when topped up to the max level, it needs to be filled to the very top of the max mark (even though you say it's above, which is confusing!) It may also be a problem with the hand brake sensor switch which again would cause the same, although you won't get an error code with that. Yes it's definitely right up at the max fill line now. Brake pedal is still fine. I can sit in the car with the engine running and pull the handbrake up and down multiple times without the issue arising. Speaking to Gav I think it's got to be sensor related. Brake pedal position sensor? or Brake fluid sensor? Went down the road and braked hard from 30MPH and all was fine (albeit the light came on). ABS light doesn't wink or anything. Bit puzzled, as you said, I really need to get my rear in gear and check the error codes tomorrow morn. I've been informed that the Emanage blue keeps the map settings in non-volatile storage so removing the battery won't lose me my map. Quote Link to comment Share on other sites More sharing options...
Homer Posted August 1, 2009 Share Posted August 1, 2009 Speaking to Gav I think it's got to be sensor related. Brake pedal position sensor? or Brake fluid sensor? Bit puzzled, as you said, I really need to get my rear in gear and check the error codes tomorrow morn. I've been informed that the Emanage blue keeps the map settings in non-volatile storage so removing the battery won't lose me my map. Brake fluid level sensor in the resevoir is a posibility, if it's triggering it should store an error code for it. The EMB will store it's map, there's no issue with removing the battery provided it's all wired in correct of course! Quote Link to comment Share on other sites More sharing options...
Yaz Posted August 2, 2009 Share Posted August 2, 2009 Am I correct in thinking that in order for a code to be stored, the orange engine management light must come on and stay on, indicating that the ecu has diagnosed some form of problem, normally sensor related. I might be wrong but I thought that just the red master warning light along with another warning light ?(i.e brake warning light) then a code will not be stored. If the brake fluid is full, then must be sensor related, either brake pedal sensor or handbrake sensor. But if the light comes on only when you press the brake pedal, then it could also be to do with your brake pads, as one of them might be leaking. I know the warning light will activate not only if the pads are worn, but also if they are leaking. Might be worth a good check at Kwik Fit, or any other garage for brakes... Quote Link to comment Share on other sites More sharing options...
caseys Posted August 3, 2009 Author Share Posted August 3, 2009 I've been told it should store error codes, but I haven't actually disconnected the battery and tried to redo it to see if it stores a code because... I think the light's on because my nearside rear brake light isn't working! Going to try and get one today. *relegates himself to the idiot corner* edit: Unless anyone then comes along and tells me they've had a brake light out and haven't had this happen to them...? Quote Link to comment Share on other sites More sharing options...
caseys Posted August 3, 2009 Author Share Posted August 3, 2009 Confirmed, I'm an idiot. Changed the bulb and the problem's gone At least it's been somthing simple and cheap for a change! I should remember Occam's Razor a bit more often. Hopefully people will find this thread for the future and I'll be the only fool Quote Link to comment Share on other sites More sharing options...
Homer Posted August 3, 2009 Share Posted August 3, 2009 haha Simplest solutions first! Glad it's all sorted mate Quote Link to comment Share on other sites More sharing options...
DannoSupra Posted August 3, 2009 Share Posted August 3, 2009 Damn it, i wanted to be the hero and suggest a bulb Quote Link to comment Share on other sites More sharing options...
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