In general, auto electrical diagnosis and repairs will start with a physical inspection. The goal here is to spot any obvious signs of damage to the vehicle’s auto electrical system. A collision repair expert — who may also be an expert auto electrician or panel beater — should know which suspected or damaged areas to inspect.
There will be cases when some electrical or electronic components need to be removed or pulled apart. The same is true with some wirings. A capable auto electrician should know when this is necessary. This is done in order to conduct a deeper investigation of the damage. In instances where the damage is merely a disconnected wire, the auto technician only needs to plug it back in. You can actually do this yourself if you know which wire goes where. Otherwise, it is best to leave this task to a knowledgeable technician.