I am having issues with my 2005 Mazda 3i, Manual transmission.

Summary:

I’m having a 140 mA parasitic draw that's being pulled by the BCM.

I pulled DTC codes and got: U0140, U0155, & U2516. All three point at a shorted wire or failed board

Any ideas on possible issues before I try replacing the BCM?
Extended:

The issue started with a parasitic draw draining my battery, I replaced the battery but the draw continues draining the battery within 24 hours. I measured the current when the car’s off and I’ve narrowed it down to a 140 mA draw. When I turn the car off the draw is 230 mA, then it drops down to 140 mA about 10 seconds after I lock the car doors.

I went to work pulling fuses and I’ve further narrowed things down to Fuse F50 & F51 on the interior fuse box, these are the input fuses to the BCM: F50 is CPU POWER and F51 is HAZARD, see image. What’s weird is both F50 and F51 generate the 140 mA draw when only one is plugged in, but both being plugged in doesn’t appear to increase draw. I also pulled every other fuse on the interior box and confirmed no other fuse has an affect on the current draw. I literally only had F50 and F51 connected and all other fuses removed and still pulled 140 mA, and I tried the reverse of connecting all but F50 & F51 and this results in 0A draw.

I have tried disconnecting different connectors on the fusebox, the Front-1 connector (J01) drops the current to zero which makes sense as that connector carries the upstream power to the BCM.
Beyond that I can’t get the current to drop to zero by disconnecting any other connectors, and the results vary depending on the sequence I disconnect. The only thing that I have confirmed is disconnecting Cockpit 1 & 2 (J02 & J03) and Floor-2 (J05) cause the current draw to jump and start oscillating between 1 and 1.3A. I’m also fairly certain Floor-1 (J05) and Front-2 (J06) have no affect on the current draw. e results. Also, disconnecting Floor-2 on it's own makes the current jump up to 270 mA, then when I reconnect it the current drops to 170 mA.

I’ve checked the car over and all the lights and instruments appear to be working fine. My hunch is the BCM has gone bad and needs to be replaced but I’d like to confirm that before I go buy one.

Any ideas what else I should check?

Thank you

 

A relay control side coil stuck closed would be a good fit for that amount of draw. So if you haven't already done so, pull the relays that receive control side ground from the BCM, and check the draw as they get pulled. It would be the 3 to the left of the BCM, and any others which are not included in that diagram page.