i changed the alternator, and the battery, but it still dont work. when i start it it charges at a weak 12 volts, then after a minute or two it stops charging all together. all the wireing appears to be in order. is there an external regulator or something? i put it through the diagnostic mode and it says " P-1682" then "p-done". anyone have this issue before or any ideas?
THANKS
greg

 

If you are sort of electrically inclined, you can try this. The PCM cycles the alternator on and off almost constantly. If you look at the plug on the back, one wire should be hot (12v) with the engine running. The other wire should cycle ground from the PCM. The only thing is, I'm not sure that the PCM will cycle the ground with the connector unplugged without a DRBIII to actuate it.
You might get lucky and the problem end up being on the hot side.

 

thanks, ill have to go check that. if its not a hot side problem would i be able to bypass the pcm by running the ground side directly to ground, or would that cause more problems? modern cars cornfuse me

 

No. The PCM cycles the alternator on and off in order to maintain charging voltage in the correct range. Grounding out that wire would cause the alternator to go to 18-20v.

 

damn... to the junkyard i go... wish me luck, cause i rarely see dakotas at the local junkyard. any other mopar vehicles you know of use the same computer?

 

In the case of you having a 2000 Dakota, you have to have one from at least 97-00 as the computer changed in 2001, and I can't swear that the PCMs are the same from anything other than a 2000, although they will look the same

 

hmmm. well its not cycling with it unplugged, or at least i cant tell that it is. it seems to have a constant ground. it does however have 12v on the other wire. im wondering if the alternator i bought is bad. not to common, but not unheard of. with the battery cable disconnected from the alt. post the alt is putting out 30v, but once i reconnect the cable it reads 12v. the old one and the new one both. does that sound right?
thanks for all your help ,Im completely lost when it comes to modern engines, and thier electrical systems