vasculardoc

Hi All,

Have recently had a problem with my battery dying and thought it was all due to the fact that my better half had left the park light on for several hours without realising it. I jump started the car, all was well, took it for a good long drive in the Adelaide hills (windy windy windy !) and things were fine. Next morning battery dead again. Re jumped and drive to work, battery dead again by mid morning. Hmmmmm I think - time for new battery (pity as it is 12month old Red Top).

Replace battery and when I attached the terminals the hydraulic/brake accumulator pump started (as expected) but didn't stop - ie ran continuously for several minutes before I disconnected it. It got very hot and I was worried it would burn out/catch fire.

I did a bit of a problem solve at the time - there is no visible leak from the pressure switch on the pump, Relay 51 appears to be OK to visual inspection, fuse 15 is OK, and the brakes have never been an issue in the past. Brake fluid levels fine. Brakes not bled in a while (but fluid only 12 months old and I don't track the car)

Next day I go out to have a bit more of a think, and reconnect the battery etc, and it all functions exactly as expected - pump runs for 20 sec then stops, depress the brake pedal a few times then the pump repressurises the system and stops. Brakes function perfectly with normal pedal feel.


With the 20/20 retrospectoscope though - on occasion on a cold morning the brake/differential lights stay on for 10-30 secs and sometimes the alarm sounds then goes off immediately, and my wife did say that the other day when she came out from university there was still a sound of a pump running under the bonnet that she hadn't noticed before.

My questions are.....

Is the Relay 51 the most likely culprit or is it more likely to be a sticky/dodgy pressure switch in the pump ? How can I check which is the likely culprit without spending $300 to get a new switch only to find its a $30 relay ?

Also - most posts on searching talk about the accumulator pump not working at all rather than it running continually - is this a common fault ?

Looking forward to some insights.

Mark

Indycam

If its a bad switch , pulling the wires from the switch will stop the motor .
If its a bad relay , pulling the wires from the switch will not stop the motor .

vasculardoc

Simple and elegant - Tres Bon ! I shall try if it happens again. The only problem is that it is now all back to normality so like all intermittent faults I shall have to wait till it happens again.

dfinnegan

Be careful.

The pump is very expensive and when it fails there are no brakes!

The switch can fail both ways.

I hate to say it, but I'd replace the switch and relay rather than waiting.

Indycam

Because the pump is so freaking expensive , you might get a new switch and relay and put them on asap .
If the motor never runs to long again , happy happy joy joy !

Indycam

I did not see your post before I posted the same same post .
While I was writing mine , you posted yours .
It just looks like I copied yours .
No plagiarism involved , I promise .

dfinnegan

No worries.

Your posts are always stellar.

Simultaneous posts happen often enough.

Cheers

Indycam

If the key is in the off position the pump should not run .
If I am reading what you wrote correctly ,
"and my wife did say that the other day when she came out from university there was still a sound of a pump running under the bonnet that she hadn't noticed before."
the pump was running when the keys were out of the car ?
If that's the case , maybe the relay is sticking on ?

vasculardoc

Thanks to all. i am going to replace the relay initially, and then see what happens. The fact that it was running without the keys on suggests to me it was a relay issue rather than switch. Seems to have fixed itself anyway. I HATE intermittent faults ! :-)

justin-in-athens

I am going to revive this thread in the hopes that you guys can be of some help.

My booster pump has decided to keep running constantly. I am pretty in tune to noises and noticed immediately when my booster pump in front of the battery kept running after initial start, so hopefully I have not incurred any damage to the pump itself--which I understand is quite expensive to replace.

I have checked the fluid level, relays R51, R34 (internal inspection), fuse 15&16. All appear good.

That leads me to suspect the pressure switch.

Can it fail in such a way as to cause constant pump operation?
Is there a way to test this element alone in the equation?

mglobe

Can anyone point me to a thin-wall socket to get the pressure switch off of the pump?

FeralComprehension

I bought a thick walled unit and ground it down