alternator trouble from crank sensor?
 

Hello all

I have been having the gen light come on a few times the last couple weeks. Read in a recent post that it could be the alternator (going to have it checked). Also read to check the crank sensor as it may cause charging problems? What tests can be done on the sensor, how to check it?

thanks

Eric

If it IS the crank position sensor causing your alternator to not charge, you'll also see the effect on the tachometer, A/C and cruise control.
No tach and no charge is a good indication the computer is not seeing the crank position sensor signal.
The Crankshaft Position Sensor signal is the only way the PCM has to determine if your mechanically injected 12V engine is "running" or not.
The PCM disables the Alternator field circuit, A/C compressor clutch and I think the Cruise Control until it knows for sure that the engine is turning.
The PCM also provides the engine RPM signal to the tach gauge which is derived from those +5volt pulses from the Crank Position Sensor mounted .050" above the harmonic balancer rim.

So, If you DO still have a good tach signal and never lose it even while the ALT is trying to play hookey, it's not likely the crank sensor is to blame for the alternator problems.



K.

Mine was acting like that, sometimes when I started the truck in the AM the alternator wouldn't start charging and the light would come on. It would usually start charging after a few minutes but the light would stay on even though the volt meter showed that the alternator had begun to work. It got worse for a while and a couple of times I had to pull over, shut the truck off, and restart it to get the alt. to start charging. It wasn't the crank sensor since everything else still worked so I was guessing either the alternator or the regulator was bad (inside the PCM, great idea Dodge [duhhh]). Then one of the batteries pooped out so I replaced them both and I've yet to have a problem since then.

John

Thanks, looks like I will start with a alt/battery load test and go from there.

Eric

off topic but i just bought my 2nd alt within a 1 year period, kinda ridiculous concidering their $130

alex, what symptoms did you have? Truck will get bat/alt test this weekend.

Eric