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Flat battery - 97 4.6 HSE - new battery


argonaut
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I have searched for info on this topic and yes, there's plenty but nevertheless, I've started a new thread as my symptoms don't match fully.

The situation is as follows: my 1997 P38 had a new battery fitted just before I bought the car at the end of December. Up until now I have not experienced any battery related problems. On Saturday I moved the car and didn't use it until this morning. I went to start the car today and the battery is a flat as a run over hedgehog! Nothing, not even a click, no lights on the dashboard, completely dead. I put the battery on charge and two hours later the car started with no problem at all.

So my questions:

1) Could this be the dreaded alarm sensor and if so are there any tests I can do to narrow this down?

2) Would leaving the car unlocked cause the battery to drain? I normally leave the car unlocked at present since the passenger side door lock is defective (once again defective, I swapped it for a 2nd hand unit about a month ago as the PS door wasn't locking/unlocking with the centre locking, replacing the unit cured this problem but it's back again now.

3) Could these problems (battery and defective door lock) somehow be related?

Cheers!

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My wife recently bought a new Mazda3, when I dropped it off for the first service there was someone alongside of me arguing with the service advisor that he shouldn't have to lock his vehicle when it was locked in the garage...The service guy was trying to explain to the customer that if the vehicle isn't locked with the remote it will eventually weaken/flatten the battery because the vehicle will constantly have the sensor working when the door isn't locked.

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Two points spring to mind.

Is your car an automatic? If so, there is a statement in the Owners Handbook about leaving the car ONLY in PARK, otherwise the battery will discharge. This requirement is often overlooked. ISTR there is an indicator light which will show if the lever is not recognised as being in Park (IE the lever is correct but the XYZ switch is faulty).

You say you moved the car on Saturday, was this to a different parking spot to where you normally park it?

If so, it may have come within range of a neighbours wireless transmitter.

Even if you have used the parking position before, a 'new' piece of wireless kit could have been commissioned, and be affecting your car.

Note that Bluetooth or Broadband WiFi installations do NOT cause this problem as the frequencies are different.

More mundane domestic wireless equipment is the cause, OR much more powerful commercial transmitters.

Stray signals waking up the BECM (via the receiver) is a popular suspect, but it could of course be a conventional fault, like a glove box or load bay light not switching off.

For tests to narrow it down, look for 'sleep testing' the BECM on the Rangerovers.net site. An alternative is to find the receiver and disconnect the power lead or the aerial lead, then see if the problem goes. I've not tried this, but if you just disconnect the lead to the aerial the receiver will probably respond to the fob if you hold it very close to the rearmost RH side window.

Pulling the fuse for the Receiver also pulls the power for the tailgate, and as there is no manual release this gets a little irritating if used as a long term 'work around'.

Sleep test is also covered in the manuals, available on the RAVE CD from the Green Oval site. Download these anyway, if you are going to live with a 38A you need these if you are going to investigate problems yourself.

HTH

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Many thanks Dave.

Yes my car is an automatic and I always use P when leaving the car - matter of habit. I moved the car to be able to get my other car out of the garage and then moved the P38 back to its usual spot. As you point out though, someone might have installed something new causing interference. I just checked the car this morning, it started fine, battery seems fine again. I'll be keeping a close eye on it!

I already have the Rave CD - got that pretty much straight after getting the car as I thought I might be needing it.

I will have a look for the sleep test on RR.net

Thanks

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