I'm finding something really strange as I dive into this power issue. Holley specifies to use a fuse on the constant power to the ECU, but no fuse is specified for the switched power. Dakota Digital says that BOTH the switched and constant power need to be fused on the Door Lock Controller. They also say the constant power to the Headlight/Dome/RAP controller should be fused, but don't say the switched power should be fused. On the DD Fan Controller they say both switched and constant power should be connected to separate 5A fuses. Vintage Air shows a 30A circuit breaker for the blower, compressor clutch and ECU constant power but no fuse on the switched power to the ECU.
So what's the deal on this requirement for switched and constant power? First of all, why can't everything be switched power in the A/C system? I don't need anything to work with the key off. Same with the fan controller...why wouldn't I want switched and constant power to be on the same switched circuit? Why do they even need both switched and constant power to the CONTROLLER? Same with the door lock controller. The keyless entry and door lock switch can still actuate the door lock relays without the Dakota Digital Door Lock Controller powered up. I asked a DD tech about this and as usual he didn't have a clue.
Why would the VHX module and Cruise Control need two different power inputs? I don't need either one to work with the key off. Even the C950 ECM has two power inputs for some reason I don't understand. It doesn't need power to retain program memory. It must have something to do with the way the logic "wakes up" and resets.
Any ideas?
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