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|Chevy Impala 8th Gen Discussion W-Body 2006-2013 (2014+ Limited). Discuss all Chevy Impala 8th Generation Performance and Technical Discussion here.|
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Page 1 shows the 10A BCM fuse. It feeds the BCM, the ignition switch, _and_ the theft deterrent module.
Page 2 shows several fuses feeding into the BCM.
Page 3 shows BCM X3-18 going to interior lights dimming circuit on page 8.
Pages 4-7 show the many signals connected to the BCM.
Page 8 - see page 3 above.
Page 9 shows several lights connected to BCM.
Page 10 shows the theft deterrent connections for the BCM.
Things to fiddle with.What I think should also be done is to get an ammeter in series with the 10A BCM fuse in order to get a more accurate reading, then monitor that as you perform various tests.
1. Fuses in underhood fuse box (page 2) feeding BCM. Appears to be 6. Not sure what effect these will have. Frankly, pulling one should cause some sort of alarm condition in the BCM - ie, if it affects the BCM current, I'd expect it to go up, not down.
So what I'd do is pull each one and ohm it out to be sure they're all good and hence feeding proper voltage to their respective BCM pins.
2. On page 3 in the upper right corner, the BCM goes to the "interior lights dimming circuits". I'd fiddle with the dimmer knob while monitoring the BCM fuse to see if the current changes any. My half-baked thought is that maybe something's wonky in the dimmer causing extra current to be drawn. That said, it's not clear if the BCM watches this pin, X3-18, or only pulls it low when it closes the switch.
3. Following that same wire, it goes thru the 2A STRG WHL fuse in the underhood fuse block to the steering wheel. Again, it's not clear how or if this path affects the BCM, but I'd pull that 2A fuse (as mentioned previously), and see if the current in the 10A BCM fuse changes.
4. Page 4, pwr_and_gnd, is mostly a rehash of page 2, but notice that the ignition switch taps the 10A BCM fuse in three places. One of those is the key detector circuit. So I wonder if that little doololly in the side of the lock cylinder could be contributing to the current draw. (I think it's a Hall effect sensor that detects the presence of the metal key, but not positive.)
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