F - Auto. Dimming Outside/Inside Mirror Doesn't Switch
Pinpoint Test F: Automatic Dimming Outside/Inside Mirror Does Not Switch AutomaticallyF1 - Check Supply To Mirror
- Turn ignition switch to the RUN position.
- Gain access to mirror wiring connector as outlined.
- Using a test lamp connected to a known good ground, check circuit 298 (P/O) Crown Victoria, Grand Marquis, 640 (R/Y) Town Car for voltage.
Pin Number/Circuit Circuit Function
1 140 (BKIPK) Backup Lamps
2 57 (BK) Ground
3 298 (P/O)(Crown Victoria, Grand Marquis) Fused 12 Volt Feed
640 (R/Y) (Town Car)
Did test lamp illuminate?
YES GO to F2.
NO SERVICE circuit 298 (P/O) Crown Victoria, Grand Marquis, 640 (R/Y) Town Car for open circuit. RESTORE vehicle. RETEST system.
F2 - Check Mirror Ground Circuit
- Using an ohmmeter connected to a known good ground connect second lead to circuit 57 (BK) at mirror connector. Measure resistance.
Is resistance 5 ohms or less?
YES GO to F3.
NO SERVICE circuit 57 (BK) for open. RESTORE vehicle. RETEST system.
F3 - Check Automatic Dimming Mirror
- Gearshift lever must be in PARK for the following tests.
- Cover photocell at backside of mirror case with a cloth.
- Using a flashlight, shine light on photocell at window in upper right corner of inside rear view mirror
Did inside rear view mirror cycle to non-glare?
YES System is OK. RESTORE vehicle. RETEST system.
NO GO to F4.
F4 - Check Circuit 140 (BK/PK)
- Using test lamp, check circuit 140 (BK/PK) for voltage.
Did test lamp illuminate?
YES SERVICE transmission range sensor.
vehicle. RETEST system.