ECU is not getting any power. I have a Megasquirt MS3X and the stock ECU and neither will get any power. The CEL never comes on in the dash when the key is turned on. I just replaced the main relay in the fuse box (the big green one that sends power to the ecu) and that was not the problem. I checked with a volt meter where the ECU relay plugs into and its receiving power. Did I buy a bad relay? I cant hear or feel it click on when inserted with the key on. No fuses are broken in both fuse boxes.

The problem started when I swapped ECUs from the stock to the MS3. I ran the engine for 10 seconds or so on the MS3 to move the car and turned it off. I disconnected the stock upstream o2 sensor to plug in the new wideband o2 (Innovate LC2) and went to put the key in the on position and suddenly no power to the ecu. All the lights and radio works. Battery light and airbag light show up on the dash. Any tips would be greatly appreciated.

*UPDATE: There was a blown fuse. In fact the 15A fuse under the dash pops every time the lc2 is plugged into the oem o2 sensor wiring harness. Now I gotta find a way to make this work.

 

Where did you pull power for the wideband from? Factory plug?

Get out a voltmeter and a wiring diagram and start checking. Check power at the fuse, relay, etc, just because the fuse and relay are good, doesn't mean they are getting power.

 

Yes power is from the factory plug. It was installed on another nb1 so I know it works.

 

you should see 12v at two of the pins for the main relay. one from the injector fuse and the other from the engine fuse.

The engine fuse is in the fuse panel behind the left side of the dash. 15amp fuse. check it for damage if you do not have voltage in two spots on the relay.

 

So there was a blown fuse... the LC2 keeps popping the 15A engine fuse under the dash. Its wired into the stock O2 sensor plug and I would like to keep it that way...

 

it should not be blowing that fuse. check your wiring for shorts and make sure it is ok. the lc2 should be pulling any major load on the system.