On a 1987 Ford F-150 standard shift truck the clutch interlock switch is apparently used to simply close the circuit for the starter switch when the clutch is fully depressed - in order to prevent starting without depressing the clutch.

When it no longer works - i.e. : the starter will not work when the clutch is fully depressed -
It's time to replace it... right?

Is there a way to bypass it conveniently by simply installing a jumper from one connector to another to check out the function of the rest of the circuit?

A. Charlie

I would remove and check the continuity of the switch. The switch may also be out of adjustment. Try spraying the switch with WD-40, first.

The switch is likely worn or broken and is in need of replacment.

Yes, the switch can be by-passed temporarily for diagnostic purposes only.

But the by-pass needs to be removed as soon as the remainder of the starting circuit has been verified as functional.