OK, all's now clear. That unit is a hire car model running custom firmware. The pin is not the normal Garmin Lock which is why you're unable to find it in the settings menu.

To locate the HWID [and it won't be 1187 i'll bet], either do one or both of these: (i) As said above by Caty; or (ii) From the main screen 'Where To?/Map', press and hold the battery symbol [top RH crn] for several seconds to enter a hidden menu, then press Next>Start Test>More to show Inventory page. The HWID will be displayed in the first three entries as BXXXX-xx after Boot BLK, X-Loader and System. Press 'Back' and note the number in the 2nd line following PCB P/N. It'll be 105-xxxxx-xx format.

Please browse the unit in MSM to see if there is a gupdate.gcd file in .System. If so, please don't delete it, make a backup of it and remove it from the unit. Upload it to a host site as a .rar or zip file, post the link here and tell us the HWID and PCB P/N, then we'll proceed from there. I'm fairly sure we can fix this unit so that it's usable without it 'self-locking' periodically.