Here is a quick video review I just made for the "ES 190 Relay Buddy".

This tool tests & confirms that a relay is or isnt working properly. The only things you will need are a relay, the ES 190, and a power source. The ES 190 will cycle the relay on/off 10 times, and if there are no problems you get "green light", if there are problems you get a "red light".

It is an extremely easy tool to use & saves a lot of time.

Here is the video link ---> Tool Review : ES 190 Relay Buddy - YouTube

Here is the product link ---> Electronic Specialties 190 Relay Buddy Automotive Relay Tester : Amazon.com