Change in voltage

In fact it gets worse............

Another annoying story from the old days. "Some time in the 70's--80's" a customer came into the parts store he has about a 62ish Ford pickup. Bought some lamp enclosures and some 4537 100W landing lights. Got them all wired up with a continuous duty solenoid and THEY WILL NOT WORK. Had them mounted and grounded to the bumper on his Ford pu. The bumper was rusty under the bolts TO THE FRAME and the bumper was not grounding. Simple.