23 replies to this topic

[76lxhatch]

I replaced my prop valve recently and discovered that two of the switches I have no longer work so it seems possible that they are all broken.

Watch out for the two different types; the early single-post (switch to earth/body of valve) has different depth and pushrod/plunger diameter to the later plastic two-pin type so they aren't a straight swap. I'm sure it wouldn't be hard to cater for the difference if necessary though.

[ls2lxhatch]

The switch on the prop valve will only close when there is unequal pressure either side of the switch (brake fail).

The only way the light will come on other than brake fail is if there is a separate circuit to test the globe. Looking at the wiring diagram I can not see a test circuit.

Can some Torana owners confirm that the brake fail light does come on when the engine is started? According to the owners manual is show only be lite when the brakes have failed.

Edited by ls2lxhatch, 04 June 2009 - 11:09 PM.

[Dangerous]

From memory, it shouldn't come on when the ignition is on. On Holdens with stock 'idiot light' dashes, the ignition switch grounds the temperature and oil pressure globes to make them illuminate when the ignition is in the START position - this is to show the driver that the globes still work. For sports dashes with gauges for temperature and oil pressure, this feature is disabled, as you can see if the gauge is faulty or not. The ignition 'test' wire is a green wire, which is left disconnected from the ignition switch if a sports dash is fitted. The only time that the brake pressure warning switch will come on is if there is a brake pressure difference, which causes the piston in the brake pressure bias switch to move, the electric switch to drop its piston under spring pressure and earth out, thus causing the globe to illuminate. I reckon the rego boys have it wrong.

[fuzzypumper]

Umm, silly question, have you actually checked the dash light isnt blown? does the brake light come on when you have the park brake engaged?

I dont think he light should come on when car is started ( without park brake engaed).
The dash end of the globe is tied to 12v and the other end to the 2 switches, the park brake one and the prop valve switch, which
is open circuit to ground when screwed in(with pin pushed in) if working properly. Both circuits share the same light.

[dattoman]

PBR won't sell the switch as a seperate part
However they still put the switch into all their new master cylinders for late model vehicles
he old part # used to be P6202

I've never heard of one failing
The common reason people try to replace the switch is because its leaking fluid thru it and they think its the switch at fault
he switch is hollow... so replacing it will do no good

The master cylinder might be the issue here if the prop shuttle valve has moved.... however if thats the case the light should be on all the time

Seems like a reallly stupid reason to fail a car that has no other issues

Good luck


Oh yeah.... Ford sells the swithes under their own part #...... they are usually while not brown... and look different... but do the same job

[76lxhatch]

Where the brake safety light on the dash does not come on when you turn the key in the ignition?

I didn't notice this bit first time, that's stupid. See Dangerous' post

[fuzzypumper]

Umm, silly question, have you actually checked the dash light isnt blown? does the brake light come on when you have the park brake engaged?

I dont think he light should come on when car is started ( without park brake engaed).
The dash end of the globe is tied to 12v and the other end to the 2 switches, the park brake one and the prop valve switch, which
is open circuit to ground when screwed in(with pin pushed in) if working properly. Both circuits share the same light.

Ooops! I just tested mine with the park brake disengaged and it does flicker on mometarily when starting the car. My mistake.
Off course you normally wouldnt see it as it would be on permanently with the park brake engaged is the usual scenario.
I would still be checking the globe.
I also havent seen one of single pin switches fail but have seen plenty of the plastic dual pin types fail.

Edited by fuzzypumper, 05 June 2009 - 12:50 PM.

[ls2lxhatch]

The switch on the prop valve does nothing unless the brakes have failed. It is impossible for the switch to make the light come on during starting. If you want to confirm the brake fail switch is working then remove it from the prop valve to release the pin and earth it on the prop valve.

If the brake fail light does actually come on when the engine is started then this could only be achieved by a separate test circuit similar to the oil and temp light test circuit which would work if the prop valve switch was disconnected. (According to the owner manual it will only come on when the brakes have failed or the handbrake is applied). Applying the handbrake will test the brake fail globe.

If you can not convince the rego guys that they are wrong then you could connect the green ignition test wire to the globe as dangerous mentioned. I will post a scan of the owners manual if that helps.

[fuzzypumper]

Dangerous , sounds correct.
My LX had a standard dash originally and I upgraded it to Full unit. This is why I suppose my brake light comes on when I crank the motor(ignition in start position). However it in no affects the operation of any the remaining lights or gauges anyway.
I dont remember disconneting this green test from the ignition either when I did the dash change.

Edited by fuzzypumper, 05 June 2009 - 07:57 PM.

[Dr Terry]

Hi Guys.

Dangerous is close to the money, but this one gets a bit involved.

Firstly, LX Toranas have 2 different versions of the brake pressure switch (as already mentioned), but why do they have 2 variations ??

It goes like this. Early LX is wired the same as the LH series, where the handbrake light & the brake fail light are one in the same. This was before the introduction of ADR31 (for 1977) where 2 separate lights were compulsory.

The single pin switch was used on the early cars & the 2-pin switch was fitted to the ADR31 cars.

Ever since the EH series, Holden had been using a globe-checking system where the temp light was lit momentarily when the ignition switch was turned to the start position. It was only the temp light which did this, because unless the engine actually overheating the driver never saw it lit. The oil pressure light comes on every time the ignition is switched on, but before the engine is started, so it wasn't wired the same as the temp light. Likewise the brake light was tested when the handbrake was pulled on.

When the separate brake fail light was introduced, this same test facility was required. The brake pressure switch was wired with 2 pins which completed the circuit to the dash globe. If you look inside the 2-pin switch you will see that the pins are joined with a link. If the switch if left un-plugged, the dash light will not work, part of the fail-safe wiring. One of the wires goes to the dash light & the other to the ignition switch as part of the test circuit. To test the circuit, what you need to do is un-plug the switch & use a paper clip to bridge the 2 pins together inside the plug. Then turn the ignition to start, so the brake fail light will come on. If it doesn't find out why. It can only be the globe or the ignition switch. Once that is fixed, plug the brake pressure back in. If the light stays on, reset the switch. In the 32 years that these have been on the market, I've never needed a new switch.

Dr Terry.

[Dr Terry]

Thanks for that Doc.

His is a single pin, so the light should NOT come on when the key is turned to the start position then?

That is correct, the globe only lights up when the handbrake is pulled on or if the brake pressure switch is triggered.

Dr Terry

[ls2lxhatch]

The compliance plate on the car lists all the ADR's applicable to the car. If 31 is not on the compliance plate then point this out to the rego guys. If 31 is on the compliance plate then you will have to fit ADR31 switch.

[fuzzypumper]

The compliance plate on the car lists all the ADR's applicable to the car. If 31 is not on the compliance plate then point this out to the rego guys. If 31 is on the compliance plate then you will have to fit ADR31 switch.

Remember just changing the switch assumes the whole prop valve hasnt been changed before. The internals(sliding pistons) are different in dual vs single pin switch prop valves.