P38 battery problems

[unclebill1]

Hi guys, any clever ideas, P38, new battery, alternator checked by Lucas and pronounced OK, with everything stopped I managed to borrow a DC tong tester from work and its showing about a 3.5 to 4 amp drain on the battery, I've tested the main lead to the fuse panel under the drivers seat and nothing, the drain is on the main lead into the engine bay fuse box. pulled all the fuses one by one and also the relays and no change, the only fuses I haven't pulled are the large bank on the right of the box, the handbook says not to pull these.

Any clever ideas before I have to book it in for a diagnostic.

Cheers Bill

Oh, everything is working fine except the cruise control and I've never bothered with that anyway.

[steve_d]

Does the handbook give any reason for not pulling the fuses?

Seems to me they have to be pulled to eliminate all the options.

Steve

[David Sparkes]

Because a lot of items are powered via the BECM this is a difficult car to check by the traditional pulling fuses method.

It becomes essential you have the wiring diagram.

Have you checked if the BECM is going to sleep?

Automatic or Manual gearbox, and if Automatic, do you always leave it in Park (as you should do)?

Just as background, have you had the car long, and how long has it been doing this battery discharge?

Cheers

PS, there is nothing desperate about pulling all the MFs, except that you may have to reset the Windows, Sunroof, and Radio. If you carry on like this make sure you NEVER leave the key in the car unless the window is also left open, so you can retrieve the key if the car locks itself.

On the safety side, do you have a second key?

Does it work, both as an ordinary key and as a remote?

Does you have the EKA?

Is there any other known problem with the car?

[unclebill1]

Because a lot of items are powered via the BECM this is a difficult car to check by the traditional pulling fuses method.

It becomes essential you have the wiring diagram.

Have you checked if the BECM is going to sleep?

Automatic or Manual gearbox, and if Automatic, do you always leave it in Park (as you should do)?

Just as background, have you had the car long, and how long has it been doing this battery discharge?

Cheers

PS, there is nothing desperate about pulling all the MFs, except that you may have to reset the Windows, Sunroof, and Radio. If you carry on like this make sure you NEVER leave the key in the car unless the window is also left open, so you can retrieve the key if the car locks itself.

On the safety side, do you have a second key?

Does it work, both as an ordinary key and as a remote?

Does you have the EKA?

Is there any other known problem with the car?

Cheers for the info,

Yes I have the Rave cd discs so I have the wiring diagrams, what is the BECM, auto, yes its left in park, had it about two three years now, no problems except the cruise control as I said before, yes I have a second key, yes it works, one bad bit of design, when the batteries flat and you have a spare battery and jump leads in the boot, you cant open it because the central locking doesn't work, I suspect the the problem is in the air suspension unit, I've had a few problems in the area so I'm going to pull that fuse, other than that its been an excelent vehicle, sssh shouldn't say that.

Other than that chichester 4x4 here I come, its been a good vehicle so I don't begrudge it.

Bill

[David Sparkes]

Sorry, I didn't respond immediately, then forgot.

You asked about the BECM; this is a big gray box taking, with it's connectors and cables, all the space beneath the RH front seat. The fuse box is part of the BECM (Body Electronic Control Module, or something like that). All the ECUs in the car are connected to it, so it monitors what is going on. There is no 'Security' ECU, it's part of the BECM. The best place to find out the details is in the Electrical Section of the WORKSHOP Manual.

IIRC this will mention the Sleep test.

When awake the BECM draws AMPS, when sleeping it draws Milliamps.

With an auto gearbox I understand there is a red light near the gear change lever; the light is dark when the BECM is sleeping. My car has a manual gearbox, so I'm relying on what I recall of other people's tales.

If the problem is the BECM being awake, the most common cause is that the separate Receiver is responding to incorrect radio frequency signals. A search in this forum may reveal more, or check out the Rangerovers.net site and 38A forum, where searches will definately reveal all the details.

Good Luck.

[unclebill1]

Sorry, I didn't respond immediately, then forgot.

You asked about the BECM; this is a big gray box taking, with it's connectors and cables, all the space beneath the RH front seat. The fuse box is part of the BECM (Body Electronic Control Module, or something like that). All the ECUs in the car are connected to it, so it monitors what is going on. There is no 'Security' ECU, it's part of the BECM. The best place to find out the details is in the Electrical Section of the WORKSHOP Manual.

IIRC this will mention the Sleep test.

When awake the BECM draws AMPS, when sleeping it draws Milliamps.

With an auto gearbox I understand there is a red light near the gear change lever; the light is dark when the BECM is sleeping. My car has a manual gearbox, so I'm relying on what I recall of other people's tales.

If the problem is the BECM being awake, the most common cause is that the separate Receiver is responding to incorrect radio frequency signals. A search in this forum may reveal more, or check out the Rangerovers.net site and 38A forum, where searches will definately reveal all the details.

Good Luck.

Cheers very much for that info, I did actually tong test the main feed to the fuse box under the RH front seat and the power was milliamps, I will check your sugestion about the red light next to the gear selector, I just assumed it was part of the alarm system, problem is that there is no Haines book of lies for the P38, I'm going to pull the main fuse to the air suspension as I've had a small problem in the area, if no joy I'll get a diagnostic on it when I get time from work, in the mean time I can recommend the Black and Decker jump start pack from Halfords, had the battery die on me at work on Saturday and it spun it over no problem.

Cheers again for the input

Bill

[MogLite]

If the problem is the BECM being awake, the most common cause is that the separate Receiver is responding to incorrect radio frequency signals. A search in this forum may reveal more, or check out the Rangerovers.net site and 38A forum, where searches will definately reveal all the details.

We had the BECM kept awake by my wireless router at home.

Now my wife and I have swapped parking spaces, so her car is further away from the house, and all is fine.

Before the battery would last 36hrs, so if we used the car every day it was fine

I've got a Rovacom with the BECM package if you think it might help.

[Dave W]

A friend of mine got one of these wireless weather stations as a christmas present and installed it on the front of his garage.

His P38 suddenly started flattening it's battery overnight because the BECM was reacting to the output from the weather station and never going to sleep. It took weeks to figure out the connection of course, by which time he'd bought a new battery and had it to the dealers umpteen times for diagnostic checks.

Didn't know about the shift indicator light, that's a useful tip !