Opus and BMW (e46)

**captain_jim1** · 05-13-2004, 01:02 PM

I'm waiting on my Opus ... but I started planning the wiring... now I need to tap into a ignition source to let the Opus no when to turn off/on, right?

Unfortunatley, all of the ignition sources in the e46 (the current 3 series) turn off while cranking... this is a problem isn't for the Opus .. Part of the appeal of an Opus is that it survives cranking .. say I'm parked somewhere with the carputer on, decided to start the car, the ignition source will turn off when I crank, the Opus will signal the shutdown, then the car will statrt, ignition back on .. will the Opus then signal a startup? What will happen?

Anyone know the best place to wire an Opus in an e46?

Very confused--
-Brad

**rando** · 05-13-2004, 02:17 PM

It should work fine. There is a programmable delay between the time when your ignition lines goes low and the Opus signals the motherboard. As long as the ignition line goes high again, the Opus will never send the shutdown signal.

**captain_jim1** · 05-13-2004, 04:24 PM

Sweet!!

Now, does anyone the best place to tap into the ignition line on an e46? I want to locate the computer in the trunk where the battery is....

-Brad

**lgbr** · 05-13-2004, 06:26 PM

Take it from behind the radio/head unit.

**migrane** · 07-19-2004, 11:35 PM

Look for something called "Add-a-circuit" at your local car stereo shop and use that to wire your opus on the same fuse that goes to your radio. Here is a link to what you need to look for.
http://www.sportys.com/shoptool/info...se_Holder.html

migrane

**jedi7001** · 07-20-2004, 12:13 AM

Very cool product. I may try this. only $10 and no need to cut into my 2004 bmw. Thanks. I am assuming I have to use the fuse in a "ACC on" fuse for the ignition to turn on the accessory. i am also assuming this will handle the opus power

**philstuf** · 07-20-2004, 01:55 AM

Originally Posted by jedi7001

Very cool product. I may try this. only $10 and no need to cut into my 2004 bmw. Thanks. I am assuming I have to use the fuse in a "ACC on" fuse for the ignition to turn on the accessory. i am also assuming this will handle the opus power

Grabbing the Acc from the fuse panel is fine, just be sure to grab the protected side of the fuse so your Acc lead is protected from shorts too. Don't want to run a screw through the lead and smoke something further up the line.

Opus (and many forum members, including myself) do not reccomned taping the fuse panel for the main power lead of the Opus. The Opus documentation recommends main power be taken directly off the battery. One of those "Best Practice" things.

Oh, yeah, don't forget to fuse the main power lead CLOSE to the battery. 6 inches or less is a good rule of thumb. (10 amp for the Opus 90, 15 for the 150).

-Phil

**jedi7001** · 07-20-2004, 10:52 AM

thanks Phil. I see what you are saying about the power lin from the opus to the battery. i will be running the power to the battery through a distribution box with an inline fuse right next to the battery. I was going to run the ACC or ignition ON cable to the fuse box. Does this make sense?

One other question along these lines. My battery for the car is in the trunk (lucky me) and I have pretty short runs to my car audio and PC setup in the trunk i was wondering about my grounding options. I know most people say ground as close as you can. I was curious if I could run all of my ground to s distribution box and ground the box to my car battery. Is this safe? i would say the total length would be a few feet. Thoughts?

**srcstc** · 07-20-2004, 11:54 AM

If the PC is gonna be in the trunk just get the ACC in the trunk. You can get it from the harness to the factory amp on the driver's side of the trunk.

Here's a wiring diagram: http://www.projectbimmer.com/BmwWiring.htm