33 brake warning light

[dickyb]

Hello all, I'm having a little problem with my car (1994 33 16v) which is a little strange and I wondered if anyone could shed any light.

I have fitted uprated 4 piston calipers, larger discs and a 75 twinspark master cylinder but am finding that the brake warning light is coming on when the brake pedal is pressed, an MOT failure. I know I could just remove the bulb but I'm not into bodges and would like to sort this properly so I wondered if anyone had any idea why this might be happening.

The only sensor on the car as far as I know is the one on the fluid reservoir which merely measures fluid level. The car therefore can't possibly know that the calipers are different from standard, there is nothing to sense the amount of fluid flowing, just the level so I can't understand why this is happening. The brake pads do not have wear sensor wiring on them but as far as I am aware this shouldn't be a problem as the the circuit is only completed once the pads have worn down which would then give a warning light. If there is no wire connected then surely there is no circuit and therefore no problem.

I have heard of a couple of others who have fitted uprated brakes and have encountered a similar problem but no one seems to know the answer - any ideas?

[AlfaCorseChris]

Thats funny mate, I have the exact opposite problem !

The brake light on my S2 33 went on one day and stayed permanently on, and only goes off when I PRESS the brake pedal !!!

I think mine is Alfa Control related though, so I was thinking of swapping the alfa control to see if the problem goes away.

Yours is with ABS though, isnt it ? Have you got an Alfa control ? Did your pads of the front calipers have a wear sensor on them ? Maybe there's an open loop somewhere

[dickyb]

I have the ABS setup (rear discs and ABS rear bias valve) but I don't have the full ABS system, too complicated to convert for RHD. I do have the Alfa Control but I'm not sure if that has any extra sensors or connectors for the braking system over and above a car without Alfa Control. As far as I can see there are just 2 bullet connectors on the lid of the brake fluid reservoir. At the moment the reservoir is slightly overfilled as the brakes need some more bleeding and I can't imagine that just pressing the brake pedal would reduce the level in the reservoir to such an extent that the sensor would be triggered for low fluid.

There aren't any pad wear indicators on the brake pads so the connectors on the car wiring loom have nothing connected to them. I wouldn't have thought that this would cause a problem, as far as I understand it, the circuit is only completed once the pads have worn sufficiently, i.e once the pads are worn the sensors then provide an earth for the circuit.

Perhaps I need to look into a way of adjusting the sensor on the fluid reservoir or fooling the car into thinking that pad wear sensors are fitted. Every time I modify something it bites me on the backside!

You fitted Brembos to your car didn't you Chris? I'm guessing you didn't have the same problem? Are you using an updated master cylinder?

[AlfaCorseChris]

I've got Brembos yes, but no master cylinder upgrades. The stock one works fine.

Your problem is alfa control related mate , 99% sure about this

Coz all signals go through the alfa control first and then into your dash.

Had a temp light and fuel light on all the time, and that was caused by dodgy connections on the alfa control

[dickyb]

Thanks Chris, you were absolutely right, its the Alfa Control that's the problem. I did leave it out completely when I put my car back together but I found that a lot of the electrics, lights etc wouldn't work if the Alfa Control wasn't fitted.

I disconnected everything then plugged in each connector until I found which one was causing the warning light to come on. I then found I had no rear lights or brake lights so found the connector which affects them. I now have just 2 out of the 4 plugs connected, I have all lights working and no warning light when the brake is pressed. Just need a road test to ensure that everything else is working as it should, its possible that things like the temperature warning light might now be disabled.

Thanks for you help

[AlfaCorseChris]

Not a problem mate

You need to open up that thing and clean up the contacts inside.

...not that its ever gonna work properly.. lights up like a damn Christmas Tree

[dickyb]

you're right they're a pain in the neck, I'm not worried about all the spurious lights on the Alfa Control itself as I've hidden it behind the dash. As long as it doesn't trigger any other warning lights on the dash I'll be happy. Shrew has kindly sent me another one so I'll see if that makes a difference, if not I've found a brand new one which might be worth trying.