What happens to the output if ADJ pin of a linear regulator is grounded?
This is a typical application diagram of the LT3014:

The regulator regulates the output voltage by regulating its pass transistor (between IN and OUT) such that at the ADJ pin there's a voltage of 1.22 V (&quot;ADJ pin voltage&quot; in table on page 3 in the datasheet). The output voltage gets to the ADJ pin through a voltage divider (the 3.92M and 1.27M resistors).
If you ground the ADJ pin then the regulator will &quot;think&quot; that the output voltage is very low. The regulator will then fully open its pass transistor in an attempt to increase the output voltage. So the output voltage will be only slightly lower than the input voltage. Also no voltage regulation will occur, the regulator will behave more or less like a resistor between IN and OUT.
So grounding the ADJ output isn't very useful as the result will be very similar to just leaving out the regulator.