Handbrake Warning Pin-Out.

[Robsey]

This is a bit of a baffler for me.

I have a 1982 van with no handbrake warning lamp.

I have updated the looms on the van to 1987 specification, including the CE1 fusebox.

It seemed daft updating the electrics, and leaving one of the most obvious warning lights.

I have trawled about for years to find a pcb edge connector that will fit the handbrake warning light unit.

I have a few of these in my box of spares, and wanted to add brake fluid warning too.

So I found one which is for the fluid switch too

Terminals are:-
31, 30 and K for the fluid switch.
15 and HB for the handbrake.



I connected this up today with a modified ,(cut down) connector from an Austin Maestro loom (choke unit or instrument cluster).





The handbrake light circuit works fine...
but the fluid side baffles the poop out of me.

I assume that the K terminal is set to 12 volts when the 3-pin fluid switch is showing low fluid.

However, as soon as the light comes on (setting K to 12v), it will not go off unless I disconnect 15 and 30 or 31... or is that meant to be 81 ?

Am I meant to use a float switch on terminal 31 or am I totally mis-understanding how this works?

Any assistance on my pointless ramblings would be greatly received.

Cheers,
Rob

[ZsZ]

The handbrake section should need the ignition+ (15) and grounds at the switch (HK)

[Robsey]

The handbrake section should need the ignition+ (15) and grounds at the switch (HK)

Cheers for that - yes the handbrake part works perfectly fine.
Pins 15 and HB on my light unit.

UPDATE -
Looking online, it appears that part number 171 919 232 is a Golf mk1 part for Choke and Hand-brake.

That may explain stuff - but I am not sure why it is / was in our T25.

2nd UPDATE: -
After another faff this evening.

I am planning to cut my losses and just use the handbrake circuit.
And piggy-back the fluid warning switch in parallel to the handbrake switch.

Hmm, be nice to fit a flashing LED for the fluid circuit though.
Hmm - easy enough to fit / achieve.

[AngeloEvs]

On later models ( post 1986/7) there is one bulb in the warning housing and it connects to the handbrake and the brake fluid resevoir switch but a resistor is fitted  in line with the hand brake switch.   This gives the bulb two brightness levels depending on which switch is grounding the bulb - the brighter level being low Brake Fluid warning.    






 

[Robsey]

Thanks for the reply,
A font of great knowledge as always.

For completeness, here is the insides of the light unit.

As you suggest for the proper unit, it has only one bulb slot...



but as you see, more than just one resistor.





The listings for this part all say Golf Mk1 Choke and Handbrake.
And this one is date stamped 7.83

Oddly, I cannot find a schematic for this particular fitment on the Golf.

[Robsey]

Okay rather than faffing, I pulled out the correct handbrake / fluid warning unit from my box of bits.

Much easier for a simple sole like me, and as AngeloEVS said, is much simpler internally too.
Although on this, the resistor is on the opposite circuit.

A shared ignition live, (15)
A ground trigger line for the handbrake (HB)
And a ground trigger via a resistor for the fluid switch (F).
(Suited for the reservoir cap type switch).

I am sure the three-pin brake light switch is different - expecting a 12 volt trigger output from the switch to the warning light.

What I still find tricky is an inability to find an original VW edge connector.
This is not the end of the world though as I have achieved the same result with an edge connector from a 1980s austin ,/ rover / leyland instrument cluster cable.

It can be easily trimmed to size to suit.
In my case - an Austin / MG Maestro cluster plug.
This is the same connector as in my earlier post but now with the three extra slots trimmed off