Defogger Relay Test
- Remove defogger relay from relay box. Relay box is located behind left instrument panel. Measure resistance between relay terminals No. 85 and 86. See Fig 1. Measure resistance between relay terminals No. 30 and 87A. Each resistance should be less than 5 ohms. If resistance is as specified, go to next step. If either resistance is more than 5 ohms, replace relay.
- Using jumper wires, apply battery positive to relay terminals No. 30 and 86. Measure voltage between battery negative and relay terminal No. 87a. Battery voltage should exist. If battery voltage exists, leave battery positive connected and go to next step. If battery voltage does not exist, replace relay.
- Using jumper wire, apply battery negative to relay terminal No. 85. Measure voltage between battery negative and relay terminal No. 87. Battery voltage should exist. If battery voltage exists, relay is functioning properly. If battery voltage does not exist, replace relay.
Courtesy of FORD MOTOR CO.