HELP!!! Alternator problems.

[alemmons]

Had the alternator checked and tried two differant alternators. I checked the ground and all connections, but I am not charging. For the last few days my voltage was fluctuating from 9 volts up to 15 volts randomly. All of a sudden it droped down to 9 volts and will not start charging. The yellow wire to the alternator shows battery voltage when ignition is on. The tan wire shows nothing. There is good continuity from the terminal on the alternator to the battery. Everything I can find shows the only thing left to ccheck is the alternator, but it tests good. Please help me!

 

[alemmons]

Sorry, I forgot to mention it is a 89 with the 4.0

 

[big cherokee]

have you done a voltage drop from the alternator to the battery i have seen where it will loose almost all the charge from the alternater to the batter threw the wires. also your alternater is charging at how many volts and how many amps? should be around 13.5-14 volts.

 

[alemmons]

The alternator has been tested at 15 volts with a load. On the vehicle there is no output though, at the alternator or the battery. It is acting like there is no voltage to the excitor to tell the alternator to start charging, but the yellow has voltage. Maybe someone could check their cables and see what they get. I have done the upgrade already to some nice 2 guage power cables. Am I correct in thinking that I am supposed to have battery voltage to the yellow wire, and nothing at the tan?

 

[alemmons]

Does the tan wire have any purpose in the charging system? Would it still charge without that wire? Just trying to make sure I am checking every possible solution. Every one says that is for the guages, but I was just curious if it did anything else.