I installed a LC-1 wideband on my G coupe and wired it to power with a add-a-line to the fuse box by the battery. During the installation a led is wired to the controller as well. I was wondering if there is always output to those fuses? I ask because no matter what fuse i hook the power up to the led never goes off even the the car off! Please help!!

 

First, if the "add-a-line" device clips around the fuse blade get rid of it immediately - they will "stretch" out the prongs in the fuse holder which will lead to intermittent issues in the future.

You need to check the voltage supply with a volt meter. If the O2 sensor is being powered with the car off you can damage the O2 sensor. They don't like to have the O2 heater on with no exhaust running over the sensor.

You should be able to tap in to an ignition wire under the dash or at the BCM.

 

It doesnt go around the original fuse, it relocates it above. I dont have a voltmeter with me at the moment but I dont understand how fuses for the stereo and seat heaters, which dont work with the key out, have power going to them at all times. Also the controller is on the passenger side so it would be nice if I could use something on that side of the car.

 

OK, those are better.

The stereo has two fuses - a constant power fuse (for memory) and a switched power fuse (to turn it on and off). I'm not sure about the seat heaters - they may or may not have a constant power source that is fed through a switched ignition. The only way to know for sure is to use a volt meter to verify.

You could also look at the service manual for your year/make/model and use that as reference (of course you will have to hope there are no mistakes in it as you don't have a volt meter to verify).