Brake failure light, self test ADR 31/

[Cobrakiller]

Hi Guys, I am using an ABS brake master cylinder and booster from a 2012 Commodore, without the ABS unit. And realized that the fluid level switch in the master cyl. reservoir is not going to comply with ADR 31. I need to fit a proportioning valve that has the brake failure switch built in like the one pictured. To comply the brake failure self test dash light needs to come on momentarily when the ignition is switched to on then go out when the engine is started and the key returned to on position. I am not sure how this deactivation with the light works, is it in the ignition switch wiring or does the switch pictured do the self test and deactivate the light somehow?

[Modena]

I can't recall the exact wording, but I do recall that if you combine the brake fluid level warning with the handbrake light, then the requirement for 'bulb test' functionality (on/off when ign on) is removed. or something like that.

[gjkrv8]

I used a diode to the Alternator light circuit. e.g. When the IGN is on and the engine is not running the voltage is low so "pulls" the light on (satisfying test function). Once the engine is up and running the light goes off, you then have the brake light switch "pull it to Earth" to satisfy the low fluid function. The only drawback is if your Alt fails both your Alt and Fluid Low lights come on. cheers Gregg

[Cobrakiller]

As this has been a requirement since the early 70's I have looked at early Holden wiring diagrams as these used a similar type of proportioning valve with the switch only having one contact + 12v and earth. But the diagram does not show any diode or timer etc. ??

[PeterAllen]

Always ask your particular engineer, but as I understand it most will accept starting the car with the handbrake on, and thus the light illuminated. Again, to my understanding (!), it's merely to show the globe works.

Happy to be corrected on this.

[Rob. Smith]

Long while back but I think the "brake fail test circuit" was wired onto the "start" terminal on the ignition switch. It comes on whilst cranking and then it goes back to the earth switch on the master cylinder once its running.

[Cobrakiller]

Thanks for the reply's, I found that the ignition switch has a earth contact between the on and start position for the test function circuit.I am using a HZ Holden switch.