Battery Drain

Hi Guys, looking for a little help with my 1999 p38 4.6 R/R, battery died on me on Sunday after visiting my dad, green flag jumped it back to life drove around 20 miles home, parked up on drive over night but left it unlocked, started first key following morning, however only drove around 8 miles parked up at lunch, locked it with fob all seemed ok, following morning dead as a door nail !!! i have been having problems with the sunroof not closing at the end of its movement would this cause the battery to go flat, fault comes up on dash as sunroof open when it appears to be closed.

Hi,
This sounds characteristic of the infamous RF receiver failure: essentially the receiver for the remote key keeps the car's computer awake, and it drains the battery - this messes up the windows and sunroof, which need to be reset, and if you're unlucky, causes key code lockout.. which is a pain...
The fix is either to upgrade the receiver to the mk III, which doesn't have this problem - although this is sadly expensive as there aren't many around anymore.
A temporary fix is to disconnect the aerial from the receiver. It is the SINGLE BLUE wire (not the cluster as that's important ), and the receiver is found beneath the rear right parcel shelf. It is a small black box.

I would also check your alternator is putting out the volts: should be about 14V at 2000rpm

Hi TCubed, thanks for prompt reply, this has happen before car kept waking up last time it was a faulty door lock car thought it was asleep and then kept waking up !!! have had new battery and alternator tested and appears to be ok, think i mastered that key code lockout from the last time lol took a while though !!! is the RF receiver a problem on a 1999 model !!!

worrall1959 said:

Hi TCubed, thanks for prompt reply, this has happen before car kept waking up last time it was a faulty door lock car thought it was asleep and then kept waking up !!! have had new battery and alternator tested and appears to be ok, think i mastered that key code lockout from the last time lol took a while though !!! is the RF receiver a problem on a 1999 model !!!

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Afraid so yes - Land Rover didn't actually work this out until about 2004... (Although in fairness there were fewer wireless signals back then).
The RF receiver can cause door locks to burn out too which isn't fun...

It's reasonably easy to check - the unit will have a green spot on it if it's a mkiii and a blue spot if a mkii or mki. Now.. this isn't definitive proof and ideally you need to check inside - Datatek has some photos somewhere of what the insides look like.

P38s HATE low battery volts, and will terrify you with about every error message they have if aflicted with them.. (When I had this problem last year I had: gearbox, ABS and traction control failures - none of which were genuine).

The good news is that Halfords generally don't know about this and so you can take drained batteries back to get replacements
Ideally you want the biggest battery that will fit for the P38 *DATATEK insert model # here*

Hi TCubed thanks for advice battery on charge at moment so will try your advice when its back on the car, if the sunroof is not closing at the point it should is there a pronlem with the motor as its not stopping at the closed point it carries on to open again !!!

worrall1959 said:

Hi TCubed thanks for advice battery on charge at moment so will try your advice when its back on the car, if the sunroof is not closing at the point it should is there a pronlem with the motor as its not stopping at the closed point it carries on to open again !!!

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Does the message centre shout about the sun roof not being set? (It should do this, along with all the windows following a battery disconnection).
You need to move them through their full travel - the sunroof can be a bit confusing as to what that is. If this doesn't work, then it could be a problem with the motor, but I don't see why it would fail half way... :/

TCubed said:

Ideally you want the biggest battery that will fit for the P38 *DATATEK insert model # here*

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People on here seem to recommend Battery Mega Store and the Alphaline 1000CCA battery they have.

Alphaline Heavy Duty Car Battery / Alphaline Commercial / Battery

Hi TCubed, the message was sunroof open !!!when you lets say open the sunroof to the tilted position and try and close it it will not stop and then goes onto slide back motion with the roof fully opened up !!!! just disconnected that blue wire in the RF receiver ready to refit the battery in the morning !!!

worrall1959 said:

Hi TCubed, the message was sunroof open !!!when you lets say open the sunroof to the tilted position and try and close it it will not stop and then goes onto slide back motion with the roof fully opened up !!!! just disconnected that blue wire in the RF receiver ready to refit the battery in the morning !!!

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It sounds as though it's not registering that it's got to a stopping point. Either that's because it's not set properly and so genuinely doesn't know, or it's not getting the information from a sensor. I'm afraid I don't know how the sunroof mechanism actually works :/ although there may be something helpful in RAVE.
Did it work before the battery woes?

Hi jacckk, the battery i bought and fitted was from europarts Bosch T3O31 90AH, cost around £125.00

Hi TCubed, no same as it is now, fault showing sunroof open when it appears shut !!!

2 things first is the sunroof set as in open and closed fully in a continuous motion . 2nd have you inspected the fuse box under the bonnet these fry themselves after about 8 yrs roughly this is of course as well as the RF receiver not instead of . Lots of odd faults thrown up by bad battery just a case of working through the process afraid.

I also have the battery drain and the doors constantly lock and unlock on their own!! Could this be the same RF receiver issue??
Where is the RF receiver physically located as I'll try disconnecting the "blue wire" this evening.

Rf receicer is under the trim beneath the rear quarter glass driver side in the boot. Little black box. 5 min job

Driver door actuator mechanism probably on the way out and may also contribute to battery drain if it keeps trying to lock itself. Only way to be sure is hook up an ammeter next to the battery and monitor to find out.

westfieldp38 said:

I also have the battery drain and the doors constantly lock and unlock on their own!! Could this be the same RF receiver issue??
Where is the RF receiver physically located as I'll try disconnecting the "blue wire" this evening.

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If you dont sort it soon you will be buying new door locks for the front as the motors will burn out

Hi sandyt, have already had to replace the n/s lock as this was causing the battery drain last time car thought it was locked and then woke up etc have disconnected the blue wire from the R/F receiver and to date (2 days) car has started !!! I know its a quick fix but there is nothing worse than trying to start it and get to work and its flat as a pancake !!!

worrall1959 said:

Hi sandyt, have already had to replace the n/s lock as this was causing the battery drain last time car thought it was locked and then woke up etc have disconnected the blue wire from the R/F receiver and to date (2 days) car has started !!! I know its a quick fix but there is nothing worse than trying to start it and get to work and its flat as a pancake !!!

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Yes there is: recharging and getting locked out

I had all these problems with mine , I've since changed RF receiver both front door locks and put on the alpha line battery and I've not had problem with battery drain since or any lock out or fob problems, cars only used on short runs but about once a fortnight / month I take it for a longer run to charge battery up especially in winter

scotchgit said:

I had all these problems with mine , I've since changed RF receiver both front door locks and put on the alpha line battery and I've not had problem with battery drain since or any lock out or fob problems, cars only used on short runs but about once a fortnight / month I take it for a longer run to charge battery up especially in winter

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+1 I did the same it is the only real fix