Possible Causes

Code 53 will set if there is a partial drop in voltage in front impact sensor circuits due to resistance to ground in sensor circuits. Code 53 will also set if there is an internal diagnostic monitor self-test failure.

1. Verify Condition  - Turn ignition on. Check for fault codes. If Code 53 is flashing, go to step 2). If Code 53 is not flashing, check connectors, wiring and crimps for intermittent problem. DO NOT  proceed with diagnostic test until code is flashing. Failure to do so will result in needless replacement of diagnostic monitor.
2. Deactivate System  - Deactivate air bag system. See COMPLETE SYSTEM DEACTIVATION  under DISABLING & ACTIVATING AIR BAG SYSTEM. Leave positive battery cable disconnected. Disconnect diagnostic monitor. On Continental, diagnostic monitor is behind knee bolster, left of steering column. On Sable and Taurus, diagnostic monitor is behind glove box. Remove plastic locking wedge from diagnostic monitor Gray connector. Set ohmmeter to AUTO or 200-k/ohm scale. Measure resistance between terminal No. 3 (Black wire) and terminals No. 2 (Yellow/White wire), No. 6 (Yellow/Light Green wire), No. 17 (Pink/Orange wire) and No. 18 (Pink/White wire) of diagnostic monitor connector. If all readings are infinite (open), replace diagnostic monitor. If any reading is not infinite, go to step 3).
3. Check Impact Sensor  - Disconnect front impact sensor whose resistance was not infinite in step 2). Measure resistance between ground and Pink/Orange wire or Pink/White wire of sensor connector. If resistance is infinite (open), locate and repair short to ground in wiring harness. If resistance is not infinite, replace impact sensor.