fuse for brake lights keeps blowing (Nissan Sentra)

[ahardb0dy]

Hello all, Found out today I have no brake lights in my 90 Sentra, pulled over and found the fuse for the brake lights was blown, the minute I put a new one in it blows, tried unplugging both rear light assemblies and put a fuse part of the way in (just touching the contacts) and it starts to spark, Tried unplugging the connector to the stop light switch at the brake pedal, same thing sparks from fuse area, found a box in the trunk on the drivers side ( brake light sensor I think), unplugged that, tried a fuse sparks again.

 

I looked at the FSM and it appears to be a pretty simple circuit other than tracing all the wires anyone have any other suggestions on what to check??

 

 

Thanks.

Edited August 24, 2011 by ahardb0dy

[ahardb0dy]

Anyone? HELP!! Pulled the stop/tail light sensor out of the trunk today after work, one of the pins looks like it got real hot as it melted the plastic that is around it and I can see what looks like a heat mark on the circuit board. Also pulled the lower dash down and unbolted the fuse box so I could check the back side of it nothing looks bad so far.

[Slartibartfast]

I'd be inclined to poke around with a multimeter where it's heat damaged.

[ahardb0dy]

Had an idea this morning, If I cut the wire coming out of the fuse box (the stop light fuse), than put a fuse in and it doesn't blow than the problem has to be between the fuse box and the brake switch. So When I got home tonight I cut that wire, put the fuse in, it didn't blow, so I cut the wire going to the brake switch and ran a jumper wire between the fuse box wire and the brake switch and the brake lights work !! So the problem has to be in the harness between the fuse box and the brake switch. Now all I have to do is connect the wire properly and try to remember how everything goes back together!!.

[ahardb0dy]

I guess the wire I cut out of the "loop" was really shorting out to ground, as before I connected the new wire I stuck my test light tip into a plug with constant power and touched the ground clip to both ends of the wire I cut and the light came on. No idea where it may be touching a ground. I taped both ends and put everything back together.