i had the same trouble i end up hiring some one to fix it for me and come to find out it was a bad ground. double check all you wiring that you did.

 

Would a 89 have a fuseable link??? Cause my truck has had brand new alternators and voltage regulators all the time over the last year and a half. Now about a week and a half ago the battery was dead so I jumped the truck and drove it for about fourty five minutes and it started chargin at 15.3 to 15.6 volts and boiled over the brand new battery. But now the battery wont charge and at the back of the alternator its only putting out less than ten volts

 

I'm real glad u guys on here that r so smart can help a guy out when its asked

 

So the ground on these voltage regulators is established where the regulator is bolted to? or do yo have to run a wire for the ground?????

 

Regulator is bad, very bad, it is likely the alternator is out too now.

 

solve your problems and get an alternator with a regulator built in

 

X2, I should have listened to my engineer friend and done this as well.

 

Hook up your external Regulator just like the old mopar cars, and disconnect the 2 wires as you were told running to the PCM. I had to track this down about 2 years ago.
The only weak link on these trucks are the electrical system.
I took all those fusible links outta the system on the drivers side fender, put in 2 heavy duty fuse blocks.
I balanced the electrical load between those 2 fuse blocks, as I'm running a 15,000# Winch, 8 Hi Output lights pointing forward, 6 pointed rearward, low profile Emergency lite bar up top between all those floodlights, battery isolater with 2- 1000 amp Interstates under the flatbed powering a 6000 watt Power Inverter....
The cops hate the flickering lights too....they will give you a ticket for that, or try to.

I Drove from Shreveport, La. to Ca. without my alternator charging, I couldn't turn off my motor cause my battery was dead, I'd just change out one of my fully charger batterys outta the back.
I have my truck now set up so if I loose my charging system, My fuel cutoff solenoid is removed, I now shutdown with a cable, I can flip a cpuple of switches on my dash and my elect. system can run off my rear batterys, if needed.

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Oh, by-the-way, ALWAYS carry a extra regulator on ya....