Engine Control Fuse - HELP!!

Brax Sisco xenex@chpl.net
Thu, 7 Mar 2002 18:42:54 -0600


Well, guys, I got a major problem.  A week or so ago, I was driving
along, shift from 1st to 2nd, and suddenly hear this bzzzzt sound (which
I now believe is the ECU relay).  Car dies, won't start, I couldn't
figure it out, guessed the distributer had died.  I took it to Nissan,
they found it was the "ECCS fuse" it's in the box next to the battery,
third one down on the right, a 7.5 amp fuse labeled engine control.  Car
was OK for the rest of the week.

Well, today I have had to replace the fuse three times so far.  I had
just done the fog light mod before all this started, so I thought maybe
I had created a short.  I completely went over all that, it is fine.  No
shorts, all wires heat shrink covered, etc...  So it's something else.

I can just about make the fuse blow on command.  It happens when
shifting 1st to 2nd, and only when accelerating a certain way.  I can't
exactly describe how, but I can make it do it.  Everytime, I hear a
bzzzzzzzt which is quite loud, and I'm just about certain is the relay
that sits on the ECU.  That seems like where the sound comes from.  Then
it's pull over, open the hood, change the blown fuse, and up and
running.  Until I do that certain 1st to 2nd shift.

I have the JWT ECU.  Could it have gone bad?  The car runs fine
otherwise.  I guess I could replace that relay.  I'm not at all sure
what it does.  I'm looking in the Haynes book electrical diagram right
now, page 12-20 and I believe the fuse in the upper left of the diagram
is the one.  It seems to go to the ECU and to the relay.  The relay
seems to connect to the MAF, and back into the ECU?  I am going to check
MAF ground next.  Haven't done that yet.

It looks like it also goes to the camshaft pos. sensor.  I just recently
set my timing at 15*.  But everybody does this, surely that couldn't
have anything to do with it?  I can't even guess what is causing a
vlotage surge that makes this fuse blow.  Anyone have any ideas???

Thanks,

  Brax

Flaked-out '97 200sx SE-R