k this trucks is a 1993 ic and all of a sudden the thing quits charging the battery so we replace the the alternator and it still wont charge the thing. we took all the tape off the wires to see if that was the problem and there fine my buddy thinks it is the computer but im not sure wat do you guys think?

 

its either going to be a computer or a voltage regulator. get a cummins voltage regulator not one from a auto parts store. use the search button this topic is brought up weekly ot seems like

 

o well we bought one for a 94 and there wasnt even any power going to the wires so its probably the computer then huh?

 

yup, if the computer isnt working it wont relay the charge to the battery

 

ok well i will try it and see wat happens appreciate it

 

Could also be the engine speed sensor on the harmonic dampener. 93 shouldn't have an external voltage regulator unless someone added it because the computer quit telling the alternator to charge.

 

Yep, 99% of the time this will be the correct answer: Crank Sensor.

 

Let me jump in on this,,,,, so first off, 93s dont have voltage regulators? That mean its internal, in the alternator? And youre saying that the CPS can make the alternator not charge? Dang Im confused. Mine wont charge, my tach quit working um and Im getting ticked offfffff.

 

No they DO have VR's, but they integrated into the PCM (computer).
If the PCM (CPS) doesn't get a signal from the crank sensor telling it the engine is running it will not let the integrated VR tell the alternator to charge. So basically, yes.

PCM failure in these trucks is very rare. Now a dozen people will log on and tell me I'm wrong because theirs failed. They often get replaced unnecessarily in the practice of throwing parts at something without proper troubleshooting.

 

Sooo, I did a check on the Crank sensor as was showed by another guy on here Philip I believe,,and I am pretty sure it failed the test. Also my tach quit working and its plugged into factory plug. So I may go buy a Crank sensor.....