p38 electric gremlins.. help please :)

i have a 1997 p38 4.0 petrol which ive owned for about a month, yesterday it developed a weird bunch of faults which im guessing are connected, windows and the remote locking only work for around 20 seconds after turning the ignition off. once locked it will not unlock after the 20 seconds is up. so if i turn ignition off and take the keys out it locks fine if it is unlock immediately it unlocks fine. if i turn ignition off take keys out and leave it a minute or two it wont lock. If im inside with ignition on none of the windows work on front or rear buttons but if i turn the ignition off the windows start working till the dash cluster goes off.Also the front and rear wipers seem to stop on the screen wherever they feel like it.
any ideas would be welcome

Had similar issue with mine when it was damp. Most issues were sorted out by cleaning ground connections on the electrical system and fitting a new battery. These vehicle's dont like low voltages and they have a very high drain even when parked up. I have a current issue with the ecu suddenly loosing voltage and stopping it starting im sure this is due to poor connections just a case of finding then.

Do you have the key code for the vehicle to reprogram the key by turning it left right left right etc in the door? If you dont its a good idea to get it, apparently land rover can tell you. I found leaving battery off over night and then reprogramming the key to the locking system solved a few issues too. Also make sure your key fob is in good condition with new batter and check the contacts to the key battery, mine were green and corroded.

In order of preference, I would :
1. Check/replace the battery
2. Check all the earth straps (rave tells you where they are
3. Check the fuse box, they are known to fail.
Report back and if that hasn't fixed it we can move onto more complex things.

thanks for all the suggestions. its had a new battery and alternator, ive checked as many earths as i could see and cleaned the battery terminals but no luck, wasnt sure if their was a specific connector or relay that could cause the problems? i did find a yellow relay with its top hanging off it said land rover sensitive voltage relay on the side (not sure what it does) had a look on google but couldnt seem to find much about it

today i had alternator fault and then had problems starting as it came up with engine disabled press key. Im just wondering if the becm is at fault and seen that their is something called sync mate that might sort the problems out,just wondered if anybody has experience with them and if they are any good?

If you are a new owner I would have to suggest you get a Nanocom . Is a computer thingy dedicated to Land Rover Expensive but the business

Check your battery is fully charged

thanks yeh the battery is fully charged and alternator is charging at 14.4v

nemesis0124 said:

today i had alternator fault and then had problems starting as it came up with engine disabled press key. Im just wondering if the becm is at fault and seen that their is something called sync mate that might sort the problems out,just wondered if anybody has experience with them and if they are any good?

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I would suspect the alternator if ALTERNATOR FAULT is showing with the engine running. Might be current leaking back from duff diodes.

I don't think you have a sync issue so Syncmate won't help.

Seems to be a lot off issues with duff alternators atm. I agree that would be my first port of call. Perhaps there is a bad set of rectifiers in a batch.

I think it's just cold weather causing more load on alternators and weak batteries dying.
As far as the op is concerned, if the earth's and battery are known good (don't assume that the battery is good just because it's new, they can fail early) then I would be checking the fuse box and also having a look around the BECM for any signs of damp and/or corrosion.
The symptoms are classic of low voltages on the various ecu's.
First off, I would try putting the battery on charge overnight then check the voltage in the morning and an hour after you've disconnected the charger. Also, a drop test on the battery.
+1 on the Nanocom, it will do pretty much everything on the p38 and will pay for itself in short order.

nemesis0124 said:

......., ive checked as many earths as i could see ...................

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Also you will need to check earths you cannot see. quite a few are hidden behind trim panels such as the drivers (right hand) kick panel.

My suspicion is fuse box or earths . . . . .but if alternator is suspect then try following:

1. Remove battery and charge fully overnight
2. Refit battery, but disconnect alternator so it cannot have any impact.
3. Try unlock & lock several times, including your 20 second wait periods.
4. Start car as well once or twice.

If the alternator is the issue the fully charged battery should last a while. Then stop the engine, switch off, and lock the car. Now watch the dim red light next to the gear change. It should go off after about two minutes showing BECM is asleep.

I just bought one of these Clamp Meters. . . . reasonable price, and excellent for finding battery drain.