xc90 2003 locked in park
 

Have read lots of posts related to not being able to get out of park and brake lights not working. I have checked the brake switch and even replaced with a new one. Switched the REM RM15 relay with RM16. I have 12v going to the brake switch. Have not tried swopping the REM shunt RSH6, not sure what this component does ? My fault is intermitent - sometimes it allowes me to select Park sometimes not. Can anyone help me where to go next. Wondering if there is a fault on the ECM. IF so where do I look for brake related issues. I do get 'ECM-940A brake pedal sensor' fault showing on diagnostics, but get this when working ok and not working.
Just hope it is not a wiring loom fault. Thanks Steve