Big.Mike Posted October 1, 2012 Share Posted October 1, 2012 Hi All, The little red dash brake warning light has been flickering since I had fun with the EGR valve. http://forums.lr4x4.com/index.php?showtopic=78945 The brakes feel okay. My question is, what actually makes the sensor light, light. I have read that the vacuum tube from the EGR valve can cause brake problems if not properly sealed off, would this cause the problem? Cheers, Mike Quote Link to comment Share on other sites More sharing options...
western Posted October 1, 2012 Share Posted October 1, 2012 check your brake fluid level, your vehicle should have a float switch as part of the master cylinder fluid tank cap, one wire is earth, other is a 12v feed to light the red ! on the dash. Quote Link to comment Share on other sites More sharing options...
Big.Mike Posted October 1, 2012 Author Share Posted October 1, 2012 check your brake fluid level, your vehicle should have a float switch as part of the master cylinder fluid tank cap, one wire is earth, other is a 12v feed to light the red ! on the dash. Cool, so it's not got some clever brake pad sensor? I'll have a look tomorrow. (I must buy a decent torch). Quote Link to comment Share on other sites More sharing options...
mat2495 Posted October 1, 2012 Share Posted October 1, 2012 Sorry for the slight hijack, but my light comes on and off at odd times, and the fluid level never changes so far as I can tell, how sensitive is the sensor? thanks. Quote Link to comment Share on other sites More sharing options...
dailysleaze Posted October 1, 2012 Share Posted October 1, 2012 The light's also affected by the handbrake switch. You could check that + associated wiring. Quote Link to comment Share on other sites More sharing options...
Big.Mike Posted October 1, 2012 Author Share Posted October 1, 2012 The light's also affected by the handbrake switch. You could check that + associated wiring. I have a separate lamp for the handbrake. Would this one come on too? Quote Link to comment Share on other sites More sharing options...
Big.Mike Posted October 1, 2012 Author Share Posted October 1, 2012 Oh, does anyone have a preference for what type of DOT4 brake fluid? Quote Link to comment Share on other sites More sharing options...
reb78 Posted October 1, 2012 Share Posted October 1, 2012 On my 110, that light is activated by the PDWA switch attached to the bulkhead on the drivers side in the engine bay. You'll spot it as the brake pipes run ito it. It measures if there is a mismatch in breaking effort front to rear. If there is, it signifies a leak somewhere - i had a rear cylinder weeping ever so slightly and the light came on under heavy breaking. Changed the cylinder and bled and all back to normal. Quote Link to comment Share on other sites More sharing options...
western Posted October 1, 2012 Share Posted October 1, 2012 I use Halfords DOT 4 brake fluid, they don't actually make it. never given me any problem. no pad wear sensors on any Defender AFAIK. fluid level & handbrake wiring diagram attached Quote Link to comment Share on other sites More sharing options...
Big.Mike Posted October 1, 2012 Author Share Posted October 1, 2012 On my 110, that light is activated by the PDWA switch attached to the bulkhead on the drivers side in the engine bay. You'll spot it as the brake pipes run ito it. It measures if there is a mismatch in breaking effort front to rear. If there is, it signifies a leak somewhere - i had a rear cylinder weeping ever so slightly and the light came on under heavy breaking. Changed the cylinder and bled and all back to normal. Hmmm, I'm wondering if my fiddling with the vacuum pipe that goes to the EGR valve might have affected this switch. I used this as a guide: http://www.landyworld.co.uk/EGRvalve.htm. Quote Link to comment Share on other sites More sharing options...
western Posted October 1, 2012 Share Posted October 1, 2012 my 110 is same as Reb's but I've aded a fluid level float cap to, so have the best of both on one warning light. wire colours are the same black/white trace. Quote Link to comment Share on other sites More sharing options...
Big.Mike Posted October 1, 2012 Author Share Posted October 1, 2012 I use Halfords DOT 4 brake fluid, they don't actually make it. never given me any problem. no pad wear sensors on any Defender AFAIK. Yeah, I'll check it and get some tomorrow. I was being sarcastic If a Defender had wear sensors on the brakes it wouldn't be a Defender! Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 1, 2012 Share Posted October 1, 2012 On my 110, that light is activated by the PDWA switch attached to the bulkhead on the drivers side in the engine bay. You'll spot it as the brake pipes run ito it. It measures if there is a mismatch in breaking effort front to rear. If there is, it signifies a leak somewhere - i had a rear cylinder weeping ever so slightly and the light came on under heavy breaking. Changed the cylinder and bled and all back to normal. Not sure if there is a PDWA switch on the 300 TDI. My light started to come on when the level was fine, turned out there was some black gunge stuck in the float switch Quote Link to comment Share on other sites More sharing options...
western Posted October 1, 2012 Share Posted October 1, 2012 Not sure if there is a PDWA switch on the 300 TDI. My light started to come on when the level was fine, turned out there was some black gunge stuck in the float switch no there isn't just a fluid low level switch, PDWA was removed in the 1991 brake system rationalisation so all defenders had the same wiring/brake loss warning. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 1, 2012 Share Posted October 1, 2012 Hmmm, I'm wondering if my fiddling with the vacuum pipe that goes to the EGR valve might have affected this switch. I used this as a guide: http://www.landyworl...uk/EGRvalve.htm. I'd say the comment about affecting the brakes is in relation to if you have a vacuum leak you will have no brake servo assist, that shouldn't affect the light. Quote Link to comment Share on other sites More sharing options...
mmgemini Posted October 1, 2012 Share Posted October 1, 2012 I have the same problem Handbrake switch is fine. Fluid level is correct. Never been fitted with an EGR or a PDWA One day I will remember to look at the cap switch. Quote Link to comment Share on other sites More sharing options...
Big.Mike Posted October 2, 2012 Author Share Posted October 2, 2012 Right, an update. There is plenty of brake fluid in the reservoir. The connections are on, if a little loose and dirty. I've noticed that if I hit the brake, the light comes on then flickers. Pumping the brake with the engine on and the bonnet open nothing happens. I think it might be as simple as the sound proofing inside the bonnet catching the electrical connection on top of the cap and causing a break in continuity. I've turned the contacts on the cap 180 degrees hopefully job done. Cheers, Mike Quote Link to comment Share on other sites More sharing options...
Big.Mike Posted October 2, 2012 Author Share Posted October 2, 2012 job done. Er, no. I'm thinking this is more than just a bad connection. I'm looking at you earth lead. Quote Link to comment Share on other sites More sharing options...
mmgemini Posted October 3, 2012 Share Posted October 3, 2012 As I had the bonnet on my Defender open yesterday, yes I do look in there occasionally, I fiddled with the connections. Pulled them off and back on.. Result Still the same. Quote Link to comment Share on other sites More sharing options...
Big.Mike Posted October 3, 2012 Author Share Posted October 3, 2012 Still the same. How much fluid is in your reserve? The wire it quite tight to the cap, it runs through a little metal loop on the master cylinder housing, I'm going to try giving this some slack. Quote Link to comment Share on other sites More sharing options...
cackshifter Posted October 3, 2012 Share Posted October 3, 2012 I've noticed the switch in the cap is a bit paranoid; if the level is a bit below 'Max' it gives a flash, even though the level is way above 'Min', presumably as it slops about. Quote Link to comment Share on other sites More sharing options...
mmgemini Posted October 3, 2012 Share Posted October 3, 2012 Fluid level is fine. I wouldn't mind swapping a cap with a known one that isn't giving these problems,. Just to see what happensFluid level is fine Of couese it could be telling us the fluid needs changing LOL Quote Link to comment Share on other sites More sharing options...
Big.Mike Posted October 10, 2012 Author Share Posted October 10, 2012 Well, I decided to get a new sender cap. I'm going to dissect the old one and post some pictures. Still only a tenner! Quote Link to comment Share on other sites More sharing options...
cieranc Posted October 18, 2012 Share Posted October 18, 2012 Well mines old and has the PDWA valve/switch. I had a lot of travel on the brake pedal, and the light would come on towards the end of the pedal stroke. First things that came to mind were: Brake fluid leak, fluid low, bad wheel bearing/wobbly disc pushing the pistons back in caliper, bleb in flexi-hose. But it pays to keep it simple and start at the beginning. Rear shoes were right out of adjustment. Adjusted them up, problem solved. Quote Link to comment Share on other sites More sharing options...
Big.Mike Posted October 18, 2012 Author Share Posted October 18, 2012 Ha, okay. An update. I bought a new sensor cap... Turns out the min level on the bottle is nonsense. Stupid blooming level thingy... Cost me a fiver for a new sensor. Why was the level down? Simple, the seal round the cap was knackered so the fluid was escaping. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.