I have a 87 àw11 and recent problem is driving me crazy!! battery charge light and fan light in dash stay on during when engine is cold. Reaches operating temp and lighs switch off for about 1 hour of driving then lights switch off and battery not charging..
replaced the altenator with a reco one problem remained and battery was shot.
Replaced the battery and cleaned the plug too the altenator problem still there battery not charging.
Now the lights stay on even when engine gets warm.
If anyone has had the same or similar problem please speak out.

Have you confirmed that your reco alternator is actually charging?  It's a simple test if you have a multimeter.  Start the car, connect a voltmeter across the battery terminals and raise the revs from idle to approx. 2000rpm.  If the alternator is playing the game you should see a voltage of about 13.5 rising to 14.5 (ish)
 
I'm presuming that you have checked the [ENGINE], [CHARGE] and [AM2] fuses and they are OK.  Also, given that you've not reported any cranking or starting issues I'm passing over battery lead problems.
 
 

the alternator is not charging. checked the battery with a volt meter and its at 11.5v and dropping,
I've had starting problems since i bought the car, only when its cold it gives me a bit of trouble in the mornings but after a few cranks it fires up. ill go check the fuses now

checked the fuses, they were all good but replaced them anyway with new ones. battery still not charging, put a multimeter from battery lead on the alternator to the negative terminal on the batery and still showing the same reading as before even with the revs up.
i think the alternator that i bought could be a dud. i spoke to a mechanic friend of mine and he said that the regulator in the alternator could be stuffed so im gonna pull the alternator off and chuck a new reg on it next if no one has any other suggestions to what it might be

Before you open the alternator up, check out your warranty on it.  You should have some sort of come-back on it, unless it's been too long . . .

Its a 30 day warranty and its been nearly 10 days only thing is the place where I got it from is about an hours drive, so doesnt bother me too much if I take it apart

All fixed turns out the alternator they gave me was a dud. Reconditioned it as well as I coukd without a layth replaced all the components that could be replaced voltage reg, bushes ect battery is charging and all lights in dash are off :) thanks Dennis for the help and suggestions.