what should i do my truck is driving me crazy, well first the alternator was makin a bearing noise when driving so i wouldnt deal with the noise i went out n bought a new one. after putting the new one in the noise was gone but i didnt check inside with my gauges. the next day i went to work the GEN light came on which i though was wierd with a new alternator on. so i took it back to the parts store and they gave me a new one but same deal the GEN light comes on after a while and it seems the alternator is not putting out anything more than the battery itself. They even gave me my old alternator and same thing low voltage was still there.....help this is driving me crazy

PS the starter battery and alternator are all new

 

Either a bad connection somewhere, or, the voltage regulator (which, unfortunately, is part of the PCM....) has gone belly up.

 

thanks i already checked everysingle wire goin to n from the battery i was thinkin da same thing that it was the trucks computer..... a guy at a salvage yard told me most of the 700s n 800s would fit my 887 how true is that?? n how would me swaping the alternator damaged the computer???

 

Which alternator did you buy? I put one in this weekend and it is rated at 136Amps. My factory load is 117Amps. They offered me a 90Amp, which maybe would give you a low voltage code. That could theoretically be your problem.

 

The original alternator may not have been bad.... coulda been the PCM all along. Being a typical electronic part.... they fail at the least convenient times......

I have no idea about interchange.

Going to a lower amperage than stock, won't set a code.

 

If it's the regulator there's no need to swap the PCM. Just engineer an old two wire Chrysler external voltage regulator into the system. A web search will turn up howtos galore.

Before resorting to that, though, you should spend $21 on the Diagnostic Manual and pinpoint the problem accurately.

 

well we compared my old one with the new one n they r the same size which am assuming is 90 amps n i was doing just fine with it just the noise was getting a little annoyin....n after the swap is when everything started to go down hill. i even tried putting my old alternator n the same thing happen. and the new alternator is not putting out any voltage but is not chargin da battery either. oh n the other option was to put a 120 amp alternator which had a 8 ribbed pulley

 

If you put the old one back in and it gave you the same problem I'm starting to believe it is the voltage regulator. Do what Unregistered said instead of swapping the PCM. Unless you can find one cheap.

 

but isnt the alternator is externally regulated by the pcm?

 

The alternator is regulated by the PCM internally. By making an external regulator you are no longer allowing the PCM to control the alternator. Here is a link to one you can buy.

http://store.alternatorparts.com/hd-...rsion-kit.aspx

I'm sure you could make your own for pretty cheap though.