98, 300tdi Defender Brake Light

[tonic]

Hi all.


Just went on a short day trip in my non daily drive 110. Was doing some down hill decent low range no braking when the brake light decided to come on. Once back on the flat it would go off. Once in down hill no brakes, light would come on again.


When we got to the road again I tried the same scenario on bitumen, down hill using gears to brake and the light would come on.


New booster 2 years ago, plenty of fluid, good shoes, good pedal.


My only questions to the all knowing forum members is about the brake fluid filler cap. I noticed that it has 2 wires coming out of it and I noticed that the cylinder under the cap has a small hole at the bottom to I guess let fluid in to measure the level and thus the wires. Do these filler caps need regular cleaning??? Would a failing vacuum pump do this???


Otherwise, what other ideas would you all have.


Thanks in advance.

[vnx205]

As the pads wear, the brake fluid level in the reservoir drops. It doesn't need to be very low for the symptoms you describe.

It happened to me driving in Deua NP when my fluid level was down by just a couple of millimetres. I added a very small amount of fluid, probably less than 50ml so that the level was right on the full mark instead of almost on the full mark and it cured the problem.

[synthium]

The brake light also comes on when the pressure differential changes in the lines- mine did the same thing intermittently and then I realise I had a small leak in my caliper. As the leak got worse the brake light stayed on until I fixed it.