You will not have 12v there with the fuel pump running in normal operation, the relay closes the leg the other way and isolates the open test lead. Providing 12v to the test lead with the relay de-energized will provide 12v directly to the pump.well the verdict is.... I dont Fn know.... I dont get a measurement of voltage whatsoever so I dont buy that it has anything to do with the FP. but I'm not very knowledgable with all the electrical options on these trucks. I am logical though and cant make any sense of it.
Al
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