A neat diagnostic trick:

The Main Relay will click three times during the starting process. When problems arise, one of those clicks (usually the third) is missing, making those clicks a handy diagnostics tool. If you consistently hear/feel all three clicks, the Relay is fine. DO NOT REPLACE IT.


Turn ignition to ON (but not to START): Click 1
Check Engine light goes off: Click 2
You now turn the key to START: Click 3