Rear Window Defogger Relay
- Remove rear window defogger relay from central junction box. Measure resistance between rear window defogger relay terminal No. 85 and terminals No. 30, 86, 87, and 87A. See Fig 1
. If all resistances are 5 ohms or more, go to next step. If any resistance is less than 5 ohms, replace rear window defogger relay.
- Connect a jumper wire between positive battery terminal and rear window defogger relay terminal No. 30. Using a self-powered test lamp, check voltage at rear window defogger relay terminal No. 87A. If voltage exists, go to next step. If voltage does not exist, replace rear window defogger relay.
- Using 3 jumper wires, connect one jumper wire between positive battery terminal and rear window defogger relay terminal No. 30. Connect another jumper wire between positive battery terminal and rear window defogger relay terminal No. 86. Connect last jumper wire between negative battery terminal and rear window defogger relay terminal No. 85. Using a test light, check voltage at rear window defogger relay terminal No. 87. If battery voltage does not exist, replace rear window defogger relay. If battery voltage exists, rear window defogger relay is okay. Check voltage and ground supplies to rear window defogger relay.
Courtesy of FORD MOTOR CO.