muddy

Hi,

I have been experiencing some problems with the Handbrake warning light on the dashboard.
It stays on when the handbrake has been released.
I'm pretty sure the handbrake is the only thing that makes this light come on. Did check brake fluid levels and all are ok.
Is there anything else that can bring on the Handbrake warning light?

I removed the handbrake cover to see if I could gain access to the switch.
Slightly confused when looking at it as it appears that there is only one wire going to it.
checked that wire for DC volts and got 0Vdc.
How does this switch work with only one wire.
Surely there has to be a feed and a return , presumably upto the dash to turn on the light.
I have drawn a picture (Picture is preety crap)
It has a sprung loaded plunger with a brass contact at the bottom, when when the handbrake is put on the plunger moves upwards making contact with the main brass contact. When the handbrake is released the plunger moves down and breaks contact.
So my question is how does this work with only 1 wire.

Heres the picture:


Has anyone got a wiring diagram for this?

Thanks

Muddy.

Dyney

Does the brass contact have a wire going to it?
I htink you'll find (from your diagram and description) that the plunger makes conntact with the brass thing and that completes the circuit making the light come on

Clean the plunger and the spring round it and lub it with WD40.

It might help

Iain.

Dyney

Forgot to say, It sounds like the plunger is sticking so cleaning and a lub might help

David_Wallis

it only needs one wire as the car is negative ground.. ie you just switch the ground...

David

NeilA

Just a thought... On my WRX, the same light is also for fluid level. I have recently had it come on for no good reason. I checked the fluid level (actually removed the top rather than just looking through the side - did you?) and after re-fitting top, all was OK again. After it doing this a couple of times, I added a little more fluid and it has remained unlit ever since! As I said, the level looked fine anyway, but I guess the float bit had somehow got where it shouldn't and until I disturbed it removing the top it made out the level was low.

Don't know if this will help!

PS Obvious one, I guess, but does the light go out if you remove the wire to the handbarke switch? If so then that is the problem and you can completely disregard everything I have just said!

Neil.

muddy

Cheers for the replies fellas.

Plunger seems free enough, pressed it in and out with me finger.

Still don't understand the 1 wire thing, if it was working ok, I guess that there would be 12v at the switch and when the plunger is pushed in or out depends on when the contact is made. So if the contact is made (when the handbrake is applied) the 12v should then feed from the other side of the contact to the lamp in the dashboard, should it not.
If the other side of the contact was to ground (Negative) it would put negative at the same potential as +ve and something somewhere would blow, or wouldn't work.

Why was I getting 0v dc when the light was on?

Tried really hard to remove the plug from the switch but the little b*gg*r wouldn't budge. Will try again tomorrow.

Will also try removing the brake resevoir cap, and make sure any connection there is ok.

Forgot to mention that the lamp does go out sometimes, but not for long.
Which brought to my attention, this afternoon, that when I have the igniton on, (without engine on) the Handbrake light was on regardless of the handbrake being on or off, when I started the engine the Handbrake light went out.
Is this normal, it's something that you probably wouldn't think of normally.

It could also be an earth fault.
Really don't want to strip the dashboard down.
I bet its something really silly.

Thanks again.
Will report back

Muddy.

NeilA

Muddy,

The switch is on the earth, not the positive. If you imagine a circuit where the power goes from +ve on battery, through switch to lamp, then from lamp to earth, but then move the switch to the earth side of the circuit (other side of the lamp), that is what you have. The power is always going to the lamp, but until the switch makes it earth, there is no circuit. When the light is on, you should have 0v at the switch - that side is earthed. The only place you will get 12v is before the lamp. Thinking further, I guess you should get 12ish volts in the wire to the switch when the lamp is off..

Good luck!

Neil.

PS YHM

[Edited by NeilA - 2/21/2003 2:29:39 PM]

muddy

Thanks Neil,

It came to me this afternoon, It had been baffeling me all night.
Suddenly remembered that the switch could, like you said be on the -Ve side of the Lamp.


So thanks for clearing that up for me.

I had another quick look at it today, removed the plug (finally got it off) and inspected the plunger again.

Took it out for a test drive and all seems ok.
Don't know if I upset something down there, so will give it time to prove itself. Not jumping to conclusions yet.

One thing I would like to ask anybody out there is, If you could check for me when the Ignition is ON (Engine NOT stated) that the handbrake light is on, What does the lamp do when you release the handbrake? Does it go out or does it stay on?

I think I may have another problem with the Handbrake lamp, as it remains on with ignition, but when engine starts it goes out.
Could be a stray -ve getting on the lamp in that particular position of the ignition switch.

But at the moment it doesn't stay on when the engine is running which is a bonus.

Muddy

muddy

Apologies Neil, just checked my mail.

Thanks very much.

Good drawings, (Better than mine) must have too much time on your hands

Yet again Thanks.

Muddy.

NeilA

Muddy,

I think it may come on with the ignition on, but engine not running as part of the 'check that the bulb works' routine before you start. Will have a look at mine tonight and let you know!!

Neil.

And no, I don't have too much time, I just draw quick!

NeilA

Right, had a look and mine comes on when you turn on the ignition, then goes out when you start the engine, so guess you are OK. Like I said above, think it is to check the bulb works (more for its use to warn of low fluid than to warn that you've left the handbrake on).

Neil.

muddy

NeilA

Completely forgot about this post.

Thanks for checking out the "ignition on" thing.

So it seems that this is the norm
The handbrake lamp problem has not come back so I must have disturbed something when i was looking.

Much happier now

Thanks very much for your help.

Muddy.

NeilA

Muddy,

No problem mate, glad you got sorted!

Neil.