Brake warning light staying on.

[brickpaver]

I have a 2003 VXi Mk 3 (lovely motor car), currently 136K but for the past 2 years (20,000 k's approx) I have had the brake warning light coming on and off at different times but more often during or after turning a corner and then straightening up again, when the warning light will come on betore a corner, go off as I turn the corner and then come back on again once I'm going straight again,..... or sometimes the other way around.

For all intents and purposes, it's like a 'moving fluid' is triggering an on/off switch but the only fluid here is in the brake fluid reservoir, something that I checked several times from the very first time the light began turning itself on. Naturally I continue to check that the hand brake foot pedal is always right off because both foot brake pedal and low brake fluid level are indicated through the same warning light.

It is obviously only a connection problem and not a safety issue because everything still works as it should. A mechanic check has clarrified that as well.  There are two wires that run to the side of the master cylinder reservoir which I assumed would connect to a switch that I coukd replace, assuming that to be the cause, but after much searching at a Toyota spare parts desk, the bloke there could find nothing in his parts book to indicate a replacement part and even his own visual check of my car couldn't tind anything either.

.The 'problem' now is that for the past 6 months and even though everything is still working fine and the brake fluid level is right up (no visible leaks anywhere) that warning light is not going off but staying ON the whole time.

Any ideas on where to look now would be greatly appreciated.

Lance.

[Hiro]

The brake fluid level warning switch is integral to the master cylinder reservoir and thus not replaceable on its own - you'd either need a new reservoir, or failing that a whole new master cylinder.  Might be worthwhile trying to drain as much fluid out of the reservoir as you can and see if the sender is gunked up or something, bear in mind that you'll most likely need to bleed the brakes after doing this.  It is a known thing for level sensors to get flaky over time.

[brickpaver]

Thanks Hiro, that actually makes a lot of sense and is right along my own line of thinking. I am a bit surprised however that the Toyota spare parts bloke didn't seem to have this bit of information in one of his reference links on his computer screen or in his own general knowledge,....oh well, maybe he was new to the job and this was only his first week of learning the ropes.

The car is actually due in for a service in two days time so because the fluid hasn't been changed since I've owned the car (the past 60,000 k's, I suspect that a brake fluid change wouldn't go astray at the same time as the service.  Just might fix the whole problem. I'll post the results after it's all done

  Cheers

Lance.

Edited January 16, 2018 by brickpaver

[trentmeyer23]

10 minutes ago, brickpaver said:

I am a bit surprised however that the Toyota spare parts bloke didn't seem to have this bit of information in one of his reference links on his computer screen or in his own general knowledge,....oh well, maybe he was new to the job and this was only his first week of learning the ropes.

If he works in spare parts, he may not have any knowledge of faults. His job is to find and provide parts. The technicians will have that sort of information.

[brickpaver]

All tinally sorted out. Had the car up on the hoist for the service so git them to drain and change the brake fluid,....bleed the brakes of course and,.....problem solvered.!  Apparently the fluid that came out wasnt all that flash but after the change, all went back to working perfectly.

[Hiro]

1 hour ago, brickpaver said:

All tinally sorted out. Had the car up on the hoist for the service so git them to drain and change the brake fluid,....bleed the brakes of course and,.....problem solvered.!  Apparently the fluid that came out wasnt all that flash but after the change, all went back to working perfectly.

If the brake fluid looked like pond water then that would definitely go a long way to explaining the issues.....although it also usually means that the master cylinder isn't far behind, as the seals probably aren't in the best of shape

[brickpaver]

All I can do now is regularly look at the master cylinder for any signs of leaking or loss,... but at least the warning light is working normal again so that should be my first warning if anything shows up in the interim.

[campbeam]

One lesson you should have now learned is to change the brake fluid for your vehicle on a regular basis. Looks like every 2-3 years depending upon the maintenance schedule for your 2003 VXi Mk 3.

https://www.cars.com/articles/how-often-do-i-need-to-change-my-brake-fluid-1420680336417/

[trentmeyer23]

2 years or sooner depending on the humidity of where you live. The more humid, the more frequently it requires changing, as brake fluid is hygroscopic.