Location: under the instrument panel on the relay box.
1. Check relay circuits.
A) Measure the resistance between pins 1 and 3, making sure there is continuity between them (resistance should be small, i.e. circuit must be closed).
b) Measure the resistance between pins 2 and 4, making sure there is no continuity between them (resistance should tend to infinity, i.e. circuit must be open).
If these conditions are not met, replace the relay.
2. Check relay operation.
Connect the positive battery terminal to terminal 1 and the negative terminal to terminal 3. Check for continuity between terminals 2 and 4 (resistance should be small, i.e. circuit must be closed).
If this condition is not met, then replace the relay.