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I would get out my multimeter and test the connectors at the sensors. Im not really sure how they operate, im guessing closing the hood closes the circuit. There should be two wires coming from the connector. The ignition may need to be turned to on to test.
Check for power. If no power check each ground wire for continuity.
I looked up the wiring diagrams. Its for my 2010 but should be similar or the same for 2012. Brown wire is the ground, each sensor has different ground locations. I believe the right sensor + goes to the front SAM (N10/1) or to the front Prefuse (F32), the left sensor + goes to the rear SAM (N10/2).
I've got a good earth connection from the earth side of the connector to ground on both connectors.
With the ignition on, measuring the voltage on the input side of each connector, I get 5.2 volts on the passenger side and 1.8 volts on the drivers side (right hand drive). Seems a bit strange.
I've checked both switches with the latches in the closed position, and both are working properly with zero resistance between the terminals of the connector plug.. I even put a jumper wire between the plug terminals to simulate the bonnet closed situation, but still got the waring message.
It appears that the problem might be something other than the latches and sensors.
The drivers side/right side seems low, though I have no idea what it should be reading. I would guess it would be 5-6v like the left side.
Did you try checking voltage of the + wire on that connector against the cars battery? Connect your + on the multimeter to the BNBU wire then your - on the multimeter to the + battery post. Curious if its higher than the 1.8v. Rule out a bad ground.
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