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Old 02-10-2015, 11:51 PM   #55 (permalink)
spacemanspif
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Join Date: Jul 2013
Location: Dirty Jersey
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The New Focus - '07 Ford Focus ZX5
90 day: 32.44 mpg (US)
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Kill Switch

Today I got a wiring diagram book for the Focus ($20 eBay). And I'm looking at ideas to make a kill switch. Jedi_sol used his crank position sensor for a kill switch and I was considering that method as well but I'm not sure if think CKP would work well because both + and - signals go back to the computer. There is a ground nearby but I'm not sure of it's relation to the CKP. Not 100% sure if interrupting one of the CKP wires would cause the engine to stop and would need to test. Also, the computer controls the ground for the injectors and they share a common power wire, which is also shared with the coils, and am thinking this might be the easier rout to for the kill switch.





Sorry the injector/coil pic is a little hard to read, I had to take a panoramic pic to fit the whole page. I'm not really sure what the "shield" means on the CKP diagram, it could just be a heat shield but I'm not sure. Also the key says that the dotted sideways 8 means "twisted pair" (not exactly sure what that means either and if it matters for what I'm doing).

Since I'm not sure about the CKP sensor, I think that maybe the inj/coil wire would be easiest to make a kill switch; let me know if this makes sense: power wire to 1 side of relay, steal power from the supply line to power the relay (little jumper from 1 pole to the other), Other side of the relay continues to the inj/coils and the ground for the relay runs inside the cabin to the switch and is grounded in the interior nearby.

If CKP would be better/easier please speak up, I'm not very familiar with how these sensors work.

Any and all other ideas are welcome,
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-Mike

2007 Ford Focus ZX5 - 91k - SGII, pending upper and lower grill bocks - auto trans
1987 Monte Carlo SS - 5.3/4L80E swap - 13.67 @ 106
2007 Ford Focus Estate - 230k - 33mpg - Retired 4/2018
1995 Saturn SL2 - 256K miles - 44mpg - Retired 9/2014

Cost to Operate Spreadsheet for "The New Focus"

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