Engine/Transmission (1994 - 1998) '95 w/ charging problems

[MichaelMiller]

I have a 1995 ram 2500, 5spd, no frills ranch truck that is having charging system problems. I just replaced the alternator with a 136amp one from the dealer, checked all fuses, looked for a drain, and put band new batteries in it. Someone has obviously had problems before with this truck since the alternator was a 120 amp Napa one and the batteries were only a year old but would not hold a charge over night. I am wondering what else I am missing or should I try a pcm. I also have no tack reading on the instrument cluster and am wondering if that has anything to do with it. thanks.

 

[hsmith]

Check the crank sensor at the balancer. It has a connector near the oil fill tube that may have come loose. Also, it should have . 050 air gap at the balancer. Since you also have no tach signal the sensor is the problem. The PCM has to see a signal from the sensor before it will excite the alternator.

 

[Woodenhead]

hsmith has likely identified your problem. I had a similar issue with mine and the gap for the crank position sensor was OK but I pulled the connector off and cleaned it with some electrical contact cleaner. That was 7+ years ago and I haven't had a problem since, except for when the alternator actually did fry.



For the record...

The voltage on these trucks is regulated by the PCM which is why as mentioned above it needs the CPS signal. This also means if the voltage regulating part of the computer fries then you either need a new computer which is big bucks or you do some searching around here get some info on wiring in an external voltage regulator. Although it doesn't look like this is your problem since your tach isn't working either.



Mike

 

[Missouri Mule]

Your problem is your Engine Speed Sensor ( crank speed sensor) not only does it send a signal to th e computer for the Tach it activates the ASD relay (automatic shut down relay) which sends line voltage to the EVR in the PCM which helps the EVR decide aternator output ( The Battery Temp sensor located under the Driver's side battery tray also sends data to the EVR so the EVR can decide what the alternator output is going to be). EVR needs both signals to regulate the output of the alternator.

 

[MichaelMiller]

thanks guys, I will check out the crank sensor and let you know what I find