Nissan Repair: 97 J30 burn ignation fuse while start enging, electric seat, seat motor

Question
QUESTION: Hi Von,

I have 97 J30 which burn the ignition fuse (20A) while engine started about few seconds. There are couple items won't work after fuse burn such as radio, window, instruments panel light and turn light. It's all work with new fuse if do not start the engine.
The car is working fine before has this problem.

Would you please advice me what's going wrong with my J30?

Thanks,

Bobby

ANSWER: Bobby,

It sounds like the alternator is over charging and blowing fuses.  That would be my first guess since that might overload the circuits.  If you go to Autozone or Checker and they will check the charge system for free.  Other causes could be that the dimmer for the interior (instrument) lights is shorted and blowing the circuit.  But, it makes no sense since the lights work until you start the engine.  I am still going to say alternator...

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

QUESTION: Hi Von,

Thank you for answer my question.
The alternator is good after Autozone checking. The dimmer switch be able to adjust light, looks like it's good too.

There are some sound came out from engine or transmission, which sounds like ignite sparking somewhere inside. The fuse   does not burn if you won't start engine. Hopefully, the new information could give you some more sense.

Thank you for your time.

Brett

Answer
Bobby,

Sounds like you have a dead short.  Are other fuses blowing when the 20 amp master blows?  If this is the case leave the other fuses out.  Other sources for the problem could be that the radio has a short to ground but that would mean that the car would blow the fuse with the key on.  Strange that it blows when the engine runs and the charge system checked out ok.  So, lets look to see if there is something that is shorting on the engine.  If the compressor is shorted to ground that should blow the AC fuse too.  Now, I had a 240SZ where the converter had melted the electric seat motor harness to the floor pan and it popped the fuse you have going out.  I have to say I am stumped and if it were me I would remove fuses to see what is overloading the circuit when the engine is started.  I can't imagine the starter cable shorting or the starter overloading the 20 amp fuse.  But, there is a possibility...