Brake test switch query
 

Hi
I have bought an sva ok brake reservoir that has the test switch on the top of the lid. For IVA I understand I need a test function in the car? How could I do this? If the lid is wired as the switch, am I stuffed?

Brake test requirement is fullfilled by the handbrake.

When you wire up, you should have the brake warning light come on when the handbrake is engaged or the fluid level is low.

Do this by wiring the two switches in parallel to the light and then the light to earth. If either switch closes, the light will come on.

Also - this site was invaluable to me when I wired up vikki:

http://www.lbthosting.com/dutton/others/ReWire.pdf

ah so even though I have a switch already (in the reservoir), I just add another switch as the test switch inside the car regardless?
The handbrake switch could be a challenge tho as its based on a 1970 beetle and they didnt have things like this back then!
Any suggestions? Just buy a switch that is closed when the handbrake is off? Hmm not sure where to fit that....no ideal place.

Paul

thanks for this its really useful actually. Understand the switch thing now - effectively I can have as many as I like in parallel regardless of whether its on the reservoir or the dash! Just need to find the brake switch warning light on loom and adapt.

Still dunno where to put the handbrake switch tho grrr. I dont think IVA actually requires a handbrake switch(?) so may have to abort on that one.

When I went for my IVA, I had three switches that would light the warning lamp - the handbrake, the low fluid float switch and a small micro switch on the indicator stalk that had been used on the donor car for cycling through the onboard computer functions.

IVA man told me I needn't have bothered with the column switch, as it was covered by the handbrake, but that doesn't mean you can have a small temporary momentary switch in the cockpit to do the same thing if the handbrake doesn't have a switch itself.

You could probably rig up something on your handbrake with a small micro switch from maplin (momentarys - not latching. either push to make or push to break depending on which end of the lever you put it)

it'd be nice if you could, as you could leave it on after the test and you'd never forget to release the handbrake! :)

i agree! will have another ponder on this tonight - thanks again.

You just need to have a test switch, handbrake is usually used but it could be just a push button on the dash, though it would would probably need to be labled (or be a switch with a brake legend on it).

Also you will need a yellow label near the reservoir defining the correct brake fluid to use (I failed IVA on that).

CBS does sticky labels now:

http://www.cbsonline.co.uk/iva-brake...ick-4531-p.asp

And a legend sheet for labeling up your switchgear. It has a brake test label on it should you end up fitting a switch in the cockpit rather than to the handbrake:

http://www.cbsonline.co.uk/legends-s...end-4077-p.asp

I used this for the switch panel and the on the brake test switch I had on the stalk.

i bought a legend sheet at Newark. Need to get a brake pot one from Stafford show I think! Its got a yellow cap but no markings.

Marlin have supplied me with a hydraulic brake switch and four way T-piece. The T-piece obviously splits the fluid supply for the rear wheels and provides a fluid connection for the brake switch. The switch is open circuit at rest so presumably closed circuit with pressure (the brake!!) applied.

The current IVA spec says:-
The hydraulic system must be fitted with a red warning lamp, sensitive to line pressure and capable of signalling the failure of any part of the hydraulic system as soon as the brake is applied and remaining lit as long as the failure exists (with the ignition switched on). As an alternative, the warning lamp must be sensitive to the reservoir fluid level, providing the reservoir is directly connected to supply the pressure side of the master cylinder when the piston is in the “brakes off” position, so that a failure of either part of a split system would result in a continuous draining of the reservoir fluid when the control is released (see note 2 and 3).

Note 2 says:-
in the case of a conventional split system (with or without vacuum assistance) it will be assumed that a failure will result in the draining of the fluid. It may be necessary to confirm the fluid circuit through the master cylinder by documentary evidence.

I am using the Marlin supplied Master cylinder (from a Ford P100 I believe) and it looks like the one Jason has used. Does that fulfill the "alternative" method as described above and if it does what were you asked for in terms of documentary evidence.

As an option the circuit below should meet the requirement:

It fulfills the lamp testing requirement via the handbrake and the 'red warning lamp, sensitive to line pressure and capable of signalling the failure of any part of the hydraulic system as soon as the brake is applied' requirement via the change over relay. However, I can't help but think it's over complicated on the basis that if I've hit the brake pedal but I've got no brake pressure the warm and damp sensation in my seat followed by a nasty smell would probably alert me to the fact something is wrong...................!!

So prehaps I don't need a brake pedal switch and can rely on just the hydraulic swith for the brake lights and the fluid level switch and handbrake for the warning light. Or alternatively, just use a standard T-piece with no pressure switch for the rear brakes (especially as I've already fitted it....!!) and use a brake pedal swith for the brake lights.

What have you all done - hydraulic switch or brake pedal switch. Is it a simple choice or have I missed something.

Nigel

Mine's a switch on the pedal box, not on the brake line.

I think it's just a case of using the pressure sensitive switch in the line to activate your brake lights. The dash tell tale will be on you handbrake & the fluid res float switch.

Thanks for that.

But did the SVA man require you to provide any documentary evidence to 'confirm the fluid circuit through the master cylinder' .

Or is that a new requirement for the IVA. (I don't have a copy of the SVA specs)

No - he just checked the operation of the brake lights, and the warning light on the dash. Oh and that the brake lines where attached to the chassis at regular intervals

Yeah, for my IVA he gave the reservoir a visual inspection to confirm that was where the low level sensor was, and checked that the light came on when the handbrake was applied.

I did fail because there was no warning label near the reservoir defining what fluid to put in it.

Hi Nigel,
i used a low level switch on the reservoir...

http://farm3.static.flickr.com/2227/...8784fea053.jpg
Brake fluid level switch by marlinpeter, on Flickr

Pedal switch....

http://farm3.static.flickr.com/2245/...2d21d56b47.jpg
Foot brake switch by marlinpeter, on Flickr

and the BMW handbrake switch which confirms the lamp works...

http://farm3.static.flickr.com/2291/...cd8c39c167.jpg
Handbrake "On" switch by marlinpeter, on Flickr

If I did this again, i'd build a little cover over the switch as I tend to bend it with my left hand when i get in and out of the car.

Not sure if the IVA has cahnged things but i think not,

Peter

No changes apart from the need to have the brake fluid res cover marked as such:

http://www.greatoldone.co.uk/Gooster...uidrescap2.JPG

Otherwise it's a fail point - as Chris found out. All I did was buy any old res cap that had the right markings on it from eBay (I think it was from a Corolla...) and glued it on to the original lid.

Many thanks to you all.

It all sounds pretty sraight forward. I'll ditch the hydraulic switch, use a pedal switch and that'll save me having to change the T-piece at tha back (which is not easy to get to with the E36 sub frame / diff carrier in situ).

Nigel

For the test switch on the dash, does it need to be in the exempt area or can it be hidden?

It can be anywhere where it can be seen. It should have the appropriate legend on it.