P38A Flat Battery

RRob · Nov 2, 2015

Hi All,
I have noticed that if I leave my P38 diesel for more than say 10 days the battery is nearly flat and needs to be charged.
The problem isn’t an old battery as I’ve had it checked.
The issue may be due to the various bits of the electrical / electronic systems which continue to draw current when the ignition is switched off.
I normally have the interior lights switched off so not to draw current when the doors are left open.
Has anybody got any thoughts about what would drain the battery and how to rectify the problem.
Whilst the weather is still reasonably mild is the time for me to sort it out rather than when it is very cold and wet.
I would be happy to install a battery on/off switch, if this is the only way to stop the drain from the battery - but I guess I’d lose all the security codes.

Saint.V8 · Nov 2, 2015

Chief drain is the RF Receiver fro the Central Locking...this stupid little box picks up all sorts of stray RF signals and wakes the cars BeCM up to check to see if it is the right code....then if it isn't it goes to sleep again until the next signal is received....

There was a later (version 3) RF box that is a little more clever and eliminated this constant waking and sleeping of the BeCM

tarphenry · Nov 2, 2015

This has been covered many times ,use search " flat battery" and you will find pages of problems and cures

wammers · Nov 2, 2015

If you have a flat battery that is a problem they are supposed to be tall oblong things.

tomcat59alan · Nov 2, 2015

If you are leaving your motor for a while, fir a maintenance charger. The are on sale in Aldi this week £12.99.

Falk · Nov 2, 2015

tomcat59alan said:
If you are leaving your motor for a while, fir a maintenance charger. The are on sale in Aldi this week £12.99.

Agreed. I removed the antenna from my RF, still got a little drain - just put on a solar charger (I'm yet to house mine in a garage

) and let it do its business. To be fair, 10 days is not to bad!

RRob i wouldn't install an isolator as i wouldn't want to leave the BECM "dead" every time i got out the car. As saint said, YWY500170 is the updated receiver, looking at over £200. All been covered before

ukadamwest · Nov 2, 2015

could be your voltage regulator on the alternator check the output.

ukadamwest · Nov 2, 2015

tomcat59alan said:
The are on sale in Aldi this week £12.99.

You on commission from Aldi or something TCA ?

brianp38dse · Nov 2, 2015

This may help and its cheeper than new receiver,http://www.landyzone.co.uk/lz/f10/rf-reciever-work-round-258096.html

Falk · Nov 2, 2015

brianp38dse said:
This may help and its cheeper than new receiver,http://www.landyzone.co.uk/lz/f10/rf-reciever-work-round-258096.html

Thanks Brian - i may do this to mine! So just remotely switching the live to the rf off? If that relay went down, can the car still be opened (by key) and start up, or does the rf receiver cause a lockout if not active?

Originally i created a mesh cage for shielding, same effect as having the aerial off!

Zorro587 · Nov 2, 2015

Did the remote relay work around myself last week, been good thus far. I soldered the power connections to the same for the RF receiver but I've put crimp-on male/female bullet connectors on the orange wire (and relay connections) so that should the relay go down for whatever reason I can unplug from the relay and plug back together as stock install.

tomcat59alan · Nov 3, 2015

ukadamwest said:
You on commission from Aldi or something TCA ?

I own Aldi.

tomcat59alan · Nov 3, 2015

Falk said:
Thanks Brian - i may do this to mine! So just remotely switching the live to the rf off? If that relay went down, can the car still be opened (by key) and start up, or does the rf receiver cause a lockout if not active?

Originally i created a mesh cage for shielding, same effect as having the aerial off!

The extra remote makes/breaks the connection from the r/f receiver to the BECM. The receiver is always receiving signals but until the extra remote is activated the it cannot send them to the BECM

Falk · Nov 3, 2015

Ye. But if that relay goes down will it lock out the system - I.e if the receiver is not communicating with the becm will it be imobolized ?

Saint.V8 · Nov 3, 2015

Falk said:
Ye. But if that relay goes down will it lock out the system - I.e if the receiver is not communicating with the becm will it be imobolized ?

But using the mechanical key you can get in and sort the relay and re-mobilise the car

Falk · Nov 3, 2015

Still a pita....might remote it out for easier access.

tomcat59alan · Nov 3, 2015

Falk said:
Still a pita....might remote it out for easier access.

Quite right Ant, in the few years since I did the mod as posted by Brian it has never let me down. You soon get used to using 2 remotes, make sure you get a "jog" type switch so you cannot forget to switch it off. My mod cost me less than £3, better than £240+ for the newest r/f receiver.

Falk · Nov 15, 2015

Update from me on this - i looked into the relay and decided, for my usage, that removing Fuse 15 (for rf receiver), if i leave the car for a few days, is the best solution to meet my needs!

tomcat59alan · Nov 16, 2015

Falk said:
Update from me on this - i looked into the relay and decided, for my usage, that removing Fuse 15 (for rf receiver), if i leave the car for a few days, is the best solution to meet my needs!

My problem was that the battery did not last a couple of days, the rf receiver was waking the alarm up every 10 seconds thinking it was being stolen, relocking the doors till the locks burnt out. Second remote jog switch (£2.99) sorted it out but after mega bucks to sort the BECM I settled for the maintenance charger.

Falk · Nov 16, 2015

tomcat59alan said:
My problem was that the battery did not last a couple of days, the rf receiver was waking the alarm up every 10 seconds thinking it was being stolen, relocking the doors till the locks burnt out. Second remote jog switch (£2.99) sorted it out but after mega bucks to sort the BECM I settled for the maintenance charger.

Like I said - it suits me best and may work for others as it isolates the rf

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