What does your "bulb check relay" do? (Aussi spec. vehicle)

[lostmarbles]

With the help of MUD, I've worked out that this is my "bulb check relay":



We have also worked out that its purpose is to increase the dependability of my brake warning system by testing my warning bulb each time I move my "ignition key" into the "start" position. In other words, the LH light of this pairing should briefly "flash on" at this time:



But I (like others here - I would imagine) have no wiring diagram that I can be confident in. (For instance my factory-installed "low/poor vacuum alarm" is not shown on any diagram I have yet come across).

 

[lostmarbles]

By the way - this is the thread that has led me thus far:

https://forum.ih8mud.com/diesel-tech-24-volts-systems/208162-relays-gadgets-what-one.html

Now ------ My vehicle was assembled in Japan for sale in Australia. This "Australian Market" specification is clear from the Q at the end of the model designation BJ40-KCQ on my VIN plate:



(I used image resizer for this image - thanks to Cleanpool in another thread)

And despite owning this vehicle for the last 27 years, I have "only a faint suspiscion" that I may have seen that brake warning light shine during that time.

Yet I know the bulb still works because I swapped bulbs prior to taking that photo.

So what I want to know now from owners of similar vehicles are:

1. Does your brake warning light flash when you start your vehicle?
2. Does "poor vacuum" cause this light to shine (as well as activating your alarm)? (Negative for me!)........... and
3. Does your "low brake fluid sensor" activate the light?, the alarm? or both? (Mine does nothing.)

 

[roscoFJ73]

It was law when this vehicle entered australia to have a functioning brake warning light and all my Fords and Holdens of that era all had a brake light that come on with the ignition when starting.
In fact it was law in the 60s because I remember an auto electrician explaining how the red light come on in my 68 Holden HK Premier 5 litre
Normally you only have to undo the brake MC cap and the light will come on
Can you make that vac alarm work ?

 

[lostmarbles]

It was law when this vehicle entered australia to have a functioning brake warning light and all my Fords and Holdens of that era all had a brake light that come on with the ignition when starting.

Thanks Rosco - Good info for me.

....Normally you only have to undo the brake MC cap and the light will come on .....

And this too.

......Can you make that vac alarm work ?

Well that's one thing I am lucky with Rosco. It does sound to indicate "low/poor vacuum". But I was wondering if that light should be glowing at the same time the alarms sounds. And should both the alarm and light operate for "low fluid level".

 

[roscoFJ73]

Well that's one thing I am lucky with Rosco. It does sound to indicate "low/poor vacuum". But I was wondering if that light should be glowing at the same time the alarms sounds. And should both the alarm and light operate for "low fluid level".

My guess is the alarm would go off for low vac and the light for low fluid. I guess the idea would be so you would know the exact problem
Do know what the alarm sounds like? Duck quack, t/rex roar,air raid siren?They are all possibilites

My 75 series has only a light for the low vac and low fluid .
No fancy dual system like yours

 

[lostmarbles]

My guess is the alarm would go off for low vac and the light for low fluid. I guess the idea would be so you would know the exact problem

I think you're right Rosco. But I'd just love someone with a working set-up on a Aussi BJ40 BJ42 etc (or even BJ60 if it has the same light and sensors) to tell me what theirs actually does in reality.

...Do know what the alarm sounds like? Duck quack, t/rex roar,air raid siren?They are all possibilites.......

Unfortunately for me, all those options would sound more pleasant. It is a "high-pitched wail" like a ..................................

I know ........like Nana Missscoooereeee stuck on the first note of one of her songs - --- provided she has tonsilitus too

 

[freebie]

My Bj42 Canadian light stays on for ebrake or low vac and on startup. There is no audible alarm and I will check the fluid level with this light??

Cheers

 

[lostmarbles]

My Bj42 Canadian light stays on for ebrake or low vac and on startup. There is no audible alarm and I will check the fluid level with this light??...Cheers

Thanks Freebie.

Over here we call the "ebrake" the "handbrake" and that activates the RH light (of my pair).

Good to hear your confirmation that the "bulb check" is indeed occuring only with your key in the "start" position.

Is your other light (of the pair) a "seat belt warning light"?

 

[lostmarbles]

OK. This whole thread was a big "sidetrack" for me (I should be doing other things like painting my fenders/guards) and I guess I was using the excuse of "waiting for replies" to avoid getting stuck in.

But I've gotten stuck in today:

I checked out that the "Brake" bulb gets juice with the key in the on/run position - And it does:



I then checked that the brake fluid level switch achieves "continuity" with the cap removed - And it does:



So why doesn't the bulb glow? Well I checked that there was 12V across its "socket terminals" with the key in the "run position" and the brake fluid chamber cap removed. - Yes indeedy.

Only one thing for it then - Give the terminals a bit of a "tweak" so they squeeze tighter on the bulb terminals:

 

[lostmarbles]

And here we are:



The "brake" light now works for the first time in "who knows how long".

And I can confirm that the "bulb check relay" does indeed cause that light to glow whenever the key is turned to the "start position" (to perform an automatic "bulb check" at that time).

And I can also confirm that the "low/poor vacuum switch" does NOT operate this light (it operates the alarm only).

So the FSM wiring diagram is incorrect. (I knew I couldn't rely on it.)

 

[Henry James the 47th]

Glad you tracked down the source of the problem Tom.

 

[lostmarbles]

Glad you tracked down the source of the problem Tom.

Thanks HJ.

Just some additional trivia:

I noticed that the LH bulb (the "brake" bulb) was glowing a little bit dimmer than the RH bulb (the "handbrake" bulb). At first I though that maybe the bulb was crook or the terminals needed cleaning but then I realised that that is how it should be. --- Because the handbrake switch is a simple "make/break" switch whereas the level switch is more complex and has its own internal resistance. (So the left hand bulb gets reduced voltage compared to the right hand. - But it still looks bright enough beneath the red lense.)