It would be good to have the boot log from a working scope to compare.
It looks like either corrupt firmware, or basic hardware fault.
Extract from the VxWorks BSP developer's guide:
2.2.4 Detailed Boot Sequence
The following is a step-by-step description of a generic boot sequence.
Step 1: Execute romInit( )
At power-up (cold start), the processor begins execution at the romInit( ) entry
point, located in romInit.s. For resets (warm starts), the processor begins execution
at romInit( ) plus a small offset (see sysToMonitor( ) in target/config/sysLib.c).
The romInit( ) routine must be written in assembly language.
The purpose of this routine is to initialize the CPU and some portion of memory. It
does the absolute minimum amount of initialization—that is, the initialization of
essential hardware only—before jumping to romStart( ). If romInit( ) is working
correctly, the memory from LOCAL_MEM_LOCAL_ADRS through
(LOCAL_MEM_LOCAL_ADRS + LOCAL_MEM_SIZE) should be readable and
writable. If this is not the case, romInit( ) is not working properly.
In addition to initializing memory as described above, the romInit( ) routine must
also disable interrupts and clear caches. romInit( ) then configures the boot type
(cold or warm) to be a subroutine argument and branches to romStart( ) in
bootInit.c. For more information on configuring the boot type, see 2.3.7 Hardware
Considerations, p.42.
romInit( ) must do only as much device setup as is required to start executing C
code. Hardware initialization is the responsibility of the sysHwInit( ) routine in
target/config/sysLib.c, which is called later during the boot sequence.
________
Extract from VxWorks architecture supplement (WRT PPC/MPC processors):
In a standard VxWorks image, excVecInit( ) and excInit( ) install the default
exception and interrupt handlers, along with the stub for the entry and exit code,
by calling the connect routines described previously.
_________
An interesting detail from:
https://www.ee.ryerson.ca/~courses/ee8205/Data-Sheets/Tornado-VxWorks/vxworks/ref/excLib.html"Exceptions or uninitialized interrupts that occur after the vectors have been initialized by excVecInit( ), but before excInit( ) is called, cause a trap to the ROM monitor."