It depends on the charge of the system, but anywhere from 12.2 to about 13.8 Volts is acceptable.

 

I think your talking main wire?
I'm asking on the 2 small wires going to ecm .

It acted up again but seems only when hot
.
Does the battery temp sensor factor it?
I got one from another truck to try..
it seems to drop to 12.1 an stays there...
Also ,does the bench test fully check diode,?
Thanks

 

Yeah, if the PCM thinks the battery is getting to hot, it's stop charging it.

 

How do you even test that ? Read it while driving with test leads on? I'd rathe be able to test by putting meter on it off car an hold near heat source if that's doable .
An see if it changes .
I'm gonna throw other one on but want to test old one.
What should it read on wire harness ?

 

Have a scanner that can read live data? That would likely be best. I haven't found resistance values for that particular sensor.....

 

That didnt do it..only hitting it jumps it back up ..
I'll bet the brushes or diode and the problem ..
Gonna get it bench tested .

 

Low quality rebuild? Still under warranty? Just replace it.

 

Tested good in 2 different test machines.. irritating when I just had it on truck an 12.1 after I cleaned up all contacts an grounds an replaced temp sensor, [ stayed running on the 12.1 then 12.2 then 12.1 as it sat running . ] ..then I tap the alternator an it jumps to 14.1 .....gonna put one from another dakota in just to see if pcm is doing the same thing.An how it acts after it's hot

If that casing may have touched the copper windings that may have shorted out something . ..

I'd hate to have to put another pcm in ...

 

So on the 2 small wires, you cant measure voltage on them. The PCM pulses them to maintain charging rate, but it is arbitrary, not 1:1.

Odd thought, when the test machine hooks up, do they plug into the 2 port connector? I wonder if it has a bad connection in the factory harness.

 

Good question ..I didnt get a close look as they got connectors out but they did have to get something specific out to hook up depending on vehicle ..The one who tested it diid say there's a external regulator in the test machine . And they said that newer one testa the diode ,but of coarse that's not gonna show the same as if it's been running an its hot ..That seemed to be when it drops voltage an to 12.1 more.
So that's a pulsating signal in the 2 wire connector kind of like injectors? .
I might get another harness too.
What's the chance ,if I were to find a identical model engine accessories,etc that the pcm could get switched out without getting it reprogrammed?
Is there anything else besides the pcm- regulator- an battery temp sensor that can signal to lower the voltage as your driving it?