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park brake fault

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About one year ago I bought an S type 2.7d v6 , I got it privately for well under trade recommended used car price so I was expecting issues the most serious being the front shocks were completely out of gas ( It had just passed a M.O.T the previous month god knows how as it was apparent to me after driving the car a few hundered yards  ) still £100 each for two front shocks was not too bad

The other issue was after a few weeks the hand brake stuck on ( very lucky for me in my drive ) with the message park brake fault,   to cut a long story short   I have fathomed out that this is due to a partly discharged battery ,   I renewed the battery and it was ok for a couple of months but returned again .  I have checked the alternator and with the engine running the voltage comes up to around 14volts so no problems there,     I used a hydrometer  to check the SG of the battery electrolyte and the last time the fault occurred it  was very low   I then investigated what the quiescent current was with everything switched off and got a shock it was around 3 amps after several minutes


Consulting the s type manual it should be no more than 28 milliamps but read on only after 1 hour, ( In my case the quiescent current was 15milliamps after 1 hour )  as I only do small runs maybe 20 miles at a time and move the car out an in of the garage a lot I have come to the conclusion that I need to charge the battery every 2 weeks or so from the mains and that there is no actual fault with the car


Has anbody any idea what  system or systems causes the current drain for so long after switch off ?         ( i dont want to go pulling fuses to try and find out and the JAG manual does not recommend that either


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Hi Stephen, and welcome to the Club.

You need to hook it up to a CTEK (or similar) battery conditioner once a week to keep the battery topped up. No need to remove or disconnect the battery to do this, and you can attach a permanent comfort lead which makes it just a matter of plugging it in. This is what I have done with mine.

When moving it in and out of the garage, if it were mine I would drive it for a mile or so to ensure that the rich start up mixture was used and the tickover back to normal before switching off: Otherwise you will be injecting an overrich mixture when you next start it, which can choke the combustion.

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HI Steve

I think thats normal, Mine similar to that,

when you switch the ignition off, you still get power to the control modules on the car, for about 10 mins, then the 12v go off

I noticed this on mine when I changed some of my side light bulbs and number plate bulbs for led bulbs

when I switch the ignition off, the led stay lit, very dim for about 10 mins, these cars use a permanent feed to every thing, then you switch the earth through each control module to earth, to bring the item on

I noticed, they keep a very slight voltage on most things like bulbs and relays, to monitor there health, this will be the approx 3 amps for that short time and 15 millamps is quite good for leakage

Mines the same after about 2 weeks it starts to drain, so if you have a 90 AH battery, your battery should last 90AH / 0.15mA = 600 hr / 24 = 25 days

I used a Jaguar CTEK charger on mine, its keeps the battery tip top, I also have a ctek charger on my Mitsubishi, when its not in use, another summer car and the battery on that is just coming up to 10 years old

my S-type has a charge socket in the boot, when I put it in the garage I open the boot and plug in the charger, close the boot and thats it, it looks after the battery




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