Checking the front heater relay
1. Check for continuous continuity between terminals 1 and 3.
2. Check for continuous continuity between terminals 2 and 4 of the relay.
3. Check for continuity between relay terminals 4 and 5 only with battery voltage present at terminals 1 and 3.
4. If the conductivity between the relay terminals does not match the specified, then replace the relay.
Checking the rear heater relay
1. Check for continuous continuity between terminals 1 and 3 of the relay.
2. Check for continuity between relay terminals 2 and 4 only with battery voltage at terminals 1 and 3.
3. If the conductivity between the relay terminals does not match the specified, then replace the relay.