I have a 1990 dodge w150 4x4. put new alt & battery in it. still not charging wright. pull positive cable and motor dies. already went through 4 alt. could it be the black box that connects at the alt.

so you replaced it with wrong alt. how fun that.?
but what is wrong I bet is thjis
not doing step1.
S1: remove battery neg lug first.
s1a if not dont the you blew up the huge alternator main fuse
connected to the huge alternator stud wire. boom its blow up
and 100000 new alternators fail and there are more fuses too.
check them all ,skip none, that means too FUSEABLE LINKS
and do not let clerks tell you what to do. they are NOT TECHS.
find out what the truck needs first
even here is clear

sadly the SM tells this,. yup used 4 types of ALT here.

1. Rear Terminal, External Regulator, External Fan Alternator
2. Side Terminal, Internal Regulator, External Fan Alternator
3. Leece-Neville 165 Ampere Alternator
4. Integral Rear Mount Regulator, Internal Fan Alternator

lost the old OEM working (before) alternator I hope not. did you?
this is one schem./

Link "J) blow if battery lug not pulled first NEG lug.
has internal regulator here. no ECU override on 5.0


hard to find truth here, the books do not cover all 4 ways.
some ALTs are born dead with charge lamp burned out.
so make sure it is not. (called self excitation path)

You have something drawing on your battery. disconnect the nevagative cable. hook a test light between the negative cable and negative battery post and pull fuses till the test light goes out. when the test light goes out you've found the circuit that's drawing down your battery. trace the circuit and look for a short to ground or if something on that circuit is staying on.

Battery light on ! alternator isn't charging . Test the alternator electrical circuits .Main cable on the back of the alt. should have B+ voltage .Pin # 3 at the connector on the alt. should have B + voltage - fuse F10 10amp under hood fuse box supply's B+ to pin #3 . Pin's 1 & 2 at the connector go to the PCM - engine computer . This is a computer controlled charging system .
Ford PCM controlled alternator testing

Have you checked whether is the new battery faulty? Happens.

on new cars never pull the cables off while its running, it can fry your computer, charge the battery (i've gotten both bad batteries and alternators from parts stores) have the battery LOAD checked, if one cell is dead,, its never going to charge correctly, and any parts store can do this for you,, once its charged, start the car,, you should have a reading o f `13.5 to 14.5 on the battery posts, if not the alt isn't working, Make sure every single connection is clean, even where the battery grounds against the motor and car body itself,

You need to pull fuses to see,but it can still be the alternator,with a bad diode allowing the drain,remove the negative battery cable from the battery,then buy a test light,they are cheap,clip one end to the negative battery cable,and touch the tip of the test light to the battery post,and the test light will light up,cause there is a draw on the system,make sure the doors are shut,and the lights are off.Then unplug the connector on the alternator,if the test light light goes off,the alternator is the problem,if not,remove the dome light fuse,and start pulling fuses one,at a time,and putting them back in,as you go,if you pull a fuse,and the test light light goes out,that is the circuit that is drawing the voltage from the battery,leave it out,and hook cable back up,and see what does not work with the fuse still out,and that will be the problem,please rate if this was at all helpful,thank you.

Common battery drain would be 1. the light under the hood staying on when the hood is closed. 2. The vanity light over the drivers sun shade if there is anything up there that is keeping the vanity shades from closing all the way. 3. pull the fuse to the rear wiper motor, common for the wiper motor to lose it's position and tries to close even when it's already closed. 4 there is a short in your 4wd encoder motor on the transfer case.
Start with the simple and check them all one by one till you have determined where your voltage drain is coming from.
Thank you for using fixya and good luck

Clean the battery post's & give it a jump start, check that the alt is putting out 13.5 to 14 volts. If it's putting out less that 13 volts check the condition of the drive belt, good contact is a must for the alt to do it's job.If Belt is good & less than 13 volts alt is weak & cannot keep up with the load.

Have the alternator tested if it dies when positive cable removed, the car is running from battery only

Check the battery's charge condition and the Charging System itself. If the battery is more than 4 years old replace it..