Rover 420 diesel battery keeps going flat

your 3rd post, and still no year,told,country or what engine is there.
Guess UK are you?
d4 IS A/T BOX, GEAR 4 FAILURE?(lost the users guide,non here USA)

it is just warning lamp. and does not make A/t fail. if DRIVE works.
the cluster service is in the service manual , buy one
the manual shows, cluster service.
air bags defeated first, for sure and done by the same book, how.
okay.>
last year made 1999 and is Honda ACCORD CLONE.
WITH THESE ENGINES (1 OF)

I'D IGNORE THE D4 AND FIX THE ALTERNATOR.
FIRST;

petrol:
1.8 L Honda F18A I4
2.0 L Honda F20Z1 I4
2.0 L T-series turbo I4
2.3 L Honda H23A3 I4
diesel:
2.0 L L-series turbo I4

you can get guide from many sites.. i know few
like reliable-store
error codes/ fault codes, wiring diagrams, schematic diagrams, torque specs, engine info, switches functioning, assemble, disassembly, complete refurbish, repair, installation every single thing is covered
within seconds u can get the access and it's totally illustrative complete

Check that altinator belt is tight enough, it should be able to move 1/2" up and down on the side with greatest distance between pulleys, if the belt is tight enough the alternator may be damaged or faulty. Hope this helps

You need to get the alternator checked as it keeps the battery charged. If you have a multimeter, then connect it to the battery with the engine running. It should show around 13 to 14 volts. If it shows 12 or so, then the alternator is not working.

have the system checked for a draw as this will cause the battery to go flat. you don`t say but have you had the charging system checked.

Check the lines of the alternator sometimes it gets corrosives
Check the tension on the drive belt, bearings, brushes...
Take the current alternator and test it with the new one and check the voltage in the store where you purchased.
check for shorts.
check that gets enough ground.
Also, just because its new does not mean its good special if it's refurbished that I don't know where you purchase it.

I remember a time that I replaced my refurbish steering power pump 6 times. pump was defected took me 6 times. it could be the Alternator regulator to be faulty.

how you can tell if your alternator is faulty. the lights on inside your car will blink go off, when you change station on your radio go off and on, dim, fuses blowing, head lights bulb blowing... check it out.
Test the alternator both the one you have now and a new one,
get second opinion to another place.

If is refurbished and keeps dying try to get the genuine for your car.

Good luck

The alternator is going BaD . While car is running remove the negative cable and if the car stops running then the alternator is bad .

Could be your alternator is bad,belt is loose,Autozone will test for free,also check the fusible link at positive battery cable,could be burnt or melted.,

I believe the problem is the origion of the vehicle.

hi, it may be that either your battery is faulty, have it drop tested, or if that is ok your starter motor may be faulty drawing to much current, ie, it needs a recon, hope this helps