Does the air bag light flash out a code?
For the odometer, it most likely needs the gears repaired. You can get them here and read the instrucions there too. Odometer Gears - Mercury - Grand Marquis 90-97
The wiper motor park: Parking Test
The ignition switch must be in RUN for all tests. Verify proper operation of wiper system in LOW. With system operating in LOW, turn wiper system switch to OFF when wiper blades are in vertical (straight-up) position. Wipers should complete cycle and depress park (below windshield). If the wiper blades do not park, refer to appropriate bulleted condition of system below and test and service as indicated.
Motor stops when wiper switch is turned to OFF. (Does not complete cycle.)
1. Remove motor park switch connector and check for battery voltage on Circuit 65 (dark green). If battery voltage is not present, service circuit as required. If voltage is present, go to Step 2.
2. Check ground wiring at switch connector for ground. Service as required. If ground is OK, go to Step 3.
3. With both wiper motor connectors disconnected, use an ohmmeter to verify continuity (less than one ohm) between Circuits 28 and 56 in the wiring harness. If continuity is not present, trace and service as required. If continuity is OK, leave connectors disconnected and go to Step 4.
4. Check for continuity to ground terminal on gear cover at circuit terminal 28 on wiper motor. If open, replace motor. If ground is present, leave connectors disconnected and go to Step 5.
5. Verify continuity (less than one ohm resistance) between Circuits 61 and 63 in the wiring harness. If continuity is not present, trace and service as required. If lack of continuity is traced to interval governor, check wiper switch for continuity between terminals P and G. Replace switch if continuity is not present between terminals P and G. If continuity is present between terminals P and G on wiper switch, and lack of continuity has been traced to interval governor, replace governor. If continuity between Circuits 61 and 63 is OK, leave connectors disconnected and go to Step 6.
6. Check for continuity between circuit terminals 63 and 65 on wiper motor. If open, replace motor.