Defogger Relay Test
- Disconnect defogger relay located in the interior relay panel. Measure resistance between relay terminal No. 86 and all other terminals. See Fig 1
. All resistances should be less than 5 ohms. If all resistances are as specified, go to next step. If any resistance is greater 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 be present. If battery voltage is present, leave battery positive connected and go to next step. If battery voltage is not present, 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 be present. If battery voltage is present relay, is functioning properly. If battery voltage is not present, replace relay.
Courtesy of FORD MOTOR CO.