Brake Warning Light On... but everything working

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Ju@n
Posts: 725
Joined: Apr 27, 2013 1:11 PM
Location: Uruguay

Brake Warning Light On... but everything working

Post by Ju@n »

Hi
So, last weekend one of the hydraulic lines started leaking quite bad. Removed the line (it's the high pressure one that goes from the pressure flow regulator to the steering box), left it at a shop so they would replace the hose parts with new one. Checked that the hose still has the restrictor on it. Put it back where it should go. Before filling up with new ATF, I replaced both switches on the PFR because I had bought them new a while ago, since mine were leaking.
After everything was done I added ATF, I turned the steering wheel both ways several times to remove air, turned the car on, turned the steering wheel again (wheels in the air) several times. Everything was fine.

Today I went for a drive and a couple seconds after starting the car the brake warning light came on. After a bit of diagnostics it's the switch on the top, the one closes below 1.5bar.
Tomorrow I might put the old one in just to see what happens, what I find weird is that the car works as expected, steering wheel moves smoothly, no extra strengh needed, power brakes also work just fine, even the brake bomb works as I have to pump like 20 times when the car is off to loose all brake assistance.

What does that switch monitor? Even though I suspect the switch might be bad, I also suspect that if the line I changed has the restrictor removed/tampered with it might have the same effect, right?
Ju@n
Posts: 725
Joined: Apr 27, 2013 1:11 PM
Location: Uruguay

Re: Brake Warning Light On... but everything working

Post by Ju@n »

Alright, yesterday I "tested" the old switch, by poking it softly with a blunt object while having the multimeter plugged into it. It does work, as in, it goes open when I push it a bit.
Today I changed the old switch back and it seems to be working now (as in, no light in the dash).
The new switch was ATE and I must have bought it back in 2019 or 2018 :(
Tested it outside and it does work as well as the old one, maybe that 1.5 +- 0.5 bar is too much tolerance and my system is not what it used to be (?)
Nevertheless, I'm gonna leave it as is. Maybe in the future I'll have to rebuild the PS pump.
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