I want to make sure I am getting the right voltage (or ANY voltage) at the wiring going to the CTS (the one in the front of the head). Can I just turn the key on, engine off, unplug the CTS connector, and put my voltmeter probes into the connector terminals? Does it matter which probe goes where ? Could I damage anything if I hook up the probes backwards ( pos / neg)?

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88 GTA 5.7 TPI Charcoal Grey Bone Stock except for loose muffler which makes it a bit louder than normal.