Chevrolet Repair: ECM/IGN Fuse, silverado 4x4, chevrolet silverado

Question
QUESTION: I Have a 91 Chevrolet Silverado 4x4 with a 350.. It keeps blowin my ecm/ign fuse and when I replace the fuse my alternator stops charging... Do I replace the ECM or The Ignition?

ANSWER: Hey Patrick,

 The question is a bit confusing.  Are you saying that the alternator charges fine when the ECM fuse IS blown?  The vehicle shouldnt even run without an ECM fuse in it.
 The CS alternators in those years do not receive field commands from the PCM.  Charge rate is internally regulated depending on the battery sense circuit.

Wayne


---------- FOLLOW-UP ----------

QUESTION: You are right it doesnt do any thing when the fuse is blown. But when I replace the fuse the alt.. wont charge anymore...  I guess my question is how does my alt. tie in to the ECM/IGN fuse?

Answer
Hey

  I have to admit it is strange that putting the fuse in would cause the alternator to QUIT charging.  The alternator gets its main power source right from the battery and the battery load sense is through the indicator lamp on the cluster.  If there is 12v on both wires you are good to go. Unless you have a different year.
 Are you indicating actual battery voltage with an external meter or are you watching the gauge on the dash?


Wayne