Fault Identification & Testing Guidance for 12V Car Part

I have a small 12-volt car part that needs testing to identify both electrical and mechanical faults. I have some tools, but I will need further recommendations for both tests and tools.

Ideal skills and experience:
- Proficient in automotive electronics and mechanics
- Experience with fault diagnosis and testing procedures
- Able to recommend tools and equipment
- Capable of providing clear, understandable guidance