240sx - strangest electrical problem known to mankind

[SloS13]

The problem: ECU Always has power, even when car is turned off (The red ECU light is always on) and the ECU relay is always warm.

If I remove the ECU relay or fuse and replace, the 12v to the ECU will turn off and stay off.

If I disconnect and reconnect the battery, the 12v to the ecu will turn off and stay off.

If I disconnect and reconnect the ECU Harness, the 12v to the ecu will turn off and stay off.

What I have replaced:The main harness (including the 2 underhood relay boxes)Engine HarnessTransmission, main positive harnessesEngine w/all sensorsTried different ECU's

I have tried unplugging ALL connectors in the car, including those at the driver side kick-panel fuse boxes and assiociated relays, the two boxes in the passenger footwell, all relays and connectors having to do with A/C, fuel pump, stereo, the box under the center console.

I've also tried unplugging the big box of wires thats held in by the 10mm bolt in the driver side footwell and it has no effect.

Right now I have only the necessities plugged in. i.e. engine sensors, ECU, fuse boxes, relay boxes.

Unplugged are headlights, all misc. buttons and knobs for interior lighting, headlight motors, hazards, turn signals, etc.

I've spent a lot of time and money trying to figure this out. The only thing I havent yet replaced is the under-dash harness and the main interior harness(es).

The only electrical modifications on the car right now is a battery relocation. Ground is perfect, i'm using 0 gauge wire for positive and it's connected directly to starter. There are no frays in the + wire. It's high quality wire.

HEELLPPPP!!!

[180fan]

I'd check the 12v constant that's always running under the dash for damage or something tapping into it. There could be something that rubs against a harness like a pedal or some support under the dash that's biting into the harness. There isn't too much from the cluster, so it may be easier to start probing with the instrument cluster out rather than pulling the entire dash.