duthehustle93
Well-Known Member
- duthehustle93 Well-Known Member
Cmon, it's only been 6 years!!
-
We've upgraded and reskinned the forum. Notice something off? Email us at [email protected] and we'll fix it.
V1 Ignition switch "kill" wiring (5V reference and 12V woes)
duthehustle93
Well-Known Member
- duthehustle93 Well-Known Member
Alright, I think I can wrap this up. I switched 1390 (white) with the same results. I found another diagram that implies that 5199 yellow has a direct run to the run/crank relay, so I switched that and got the same results.
For those that are curious why: I dug through the manual and eventually found this. Apparently there is redundancy built into the system. They use a combination of the 5V reference and the 12V switch to communicate switch position to run features like RAP. If there is a fault with either of those lines, the BCM will default to a power mode that it reasonably assumed (ie: "calculated"). In addition, if the engine is already running and something goes wrong, the "fail safe" will retain it in run mode until the engine run flag is false. I can't fully wrap my head around it, but this is enough information to explain why this is so painful.
If someone else in the future wants to wire a kill switch, I have a few solutions:
For those that are curious why: I dug through the manual and eventually found this. Apparently there is redundancy built into the system. They use a combination of the 5V reference and the 12V switch to communicate switch position to run features like RAP. If there is a fault with either of those lines, the BCM will default to a power mode that it reasonably assumed (ie: "calculated"). In addition, if the engine is already running and something goes wrong, the "fail safe" will retain it in run mode until the engine run flag is false. I can't fully wrap my head around it, but this is enough information to explain why this is so painful.
If someone else in the future wants to wire a kill switch, I have a few solutions:
- 6 pole kill (whiteboard diagram):
- don't use the ignition switch like you might be used to... I recommend tapping into an ignition, engine, or ECU fuse for kill.
- Or, if you waited until after everything is buttoned up to do this and need to work with the ignition switch... you can put pin 2 (red/white) and a 4 or 5 pin relay (coil terminals) on the Z/2 post, and put pin 6 (white/black) on the switched contacts. So, you will open both the 12V and 5V at the same time to kill ignition.
- 4 pole w/ 5V 5-pin relay (paper diagram)... I also have a 4 pole on hand and wanted to see if there's a better option with a 4 pole. I wouldn't say it's better, but it's an option if you have a 4 pole on hand.
Attachments
Last edited:
ah.b.normal
Goblin Guru
- ah.b.normal Goblin Guru
I've read this post through and I did not notice this addressed: The fused feed that runs straight from the Batt+ to the BCM. My thinking is it should be cut as well when the big switch cuts off power? My concern is that Electricity finds it's way around, always. I've no dog in this fight beyond my curiosity finding out which way this point goes.
duthehustle93
Well-Known Member
- duthehustle93 Well-Known Member
Hello, maybe I'm missing something, but the post above with the wiring diagrams addresses this.
duthehustle93
Well-Known Member
- duthehustle93 Well-Known Member
Hi All,
To fully close this out... if anyone is referencing this in the future and wants to wire a kill switch, IMO this is the best route. Get a 6 pole (although I was recently correct that it's technically 'post' but you'll want to google 6 pole to order one) and wire it as shown. The OG racing ones ($50) I've used in the past were great quality, but the last one I got was extremely cheap feeling and likely a white label $20 amazon switch. So, I'd probably recommend getting an OMP switch (~$80).
To fully close this out... if anyone is referencing this in the future and wants to wire a kill switch, IMO this is the best route. Get a 6 pole (although I was recently correct that it's technically 'post' but you'll want to google 6 pole to order one) and wire it as shown. The OG racing ones ($50) I've used in the past were great quality, but the last one I got was extremely cheap feeling and likely a white label $20 amazon switch. So, I'd probably recommend getting an OMP switch (~$80).
- Large battery cable + BCM on one large post, battery to the other post.
- W or 1: one end will have a resistor to ground, the other will be jumped to the battery/BCM side of the large post
- Z or 2: have this interrupt BCM X3 D4. This is the best kill circuit I could find at the front of the vehicle, where you will be likely installing your kill switch. It's ECM power and this circuit is also downstream of a fuse, so your run to your kill switch will also be fused. The fuse is a 10A (#25 for the LNF, #1 on other diagrams I've seen) and it's the one at the very top right. It's barely out of frame, but you can see that I have the fuse puller currently installed on it. You can pull this fuse while the car is running, and check continuity between this fuse and the wire that my screwdriver is pointing at, to verify before you start trusting me and cutting wires.
