1. Checking the main heater relay.
A) Check for continuity between terminals "1" And "3".
b) Check for continuity between terminals "2" And "4".
V) Check for continuity between terminals "4" And "5".
G) When battery voltage is applied to the terminals "1" And "3" check for continuity between terminals "4" And "5" and lack of conduction between the terminals "2" And "4" relay.