Pinpoint Test

1. Ignition ON.
2. Move the selector lever through the entire range.

Do the reversing lamps illuminate only in REVERSE? 

• Yes: GO to 2  .
• No: REFER to SYMPTOM CHART: REVERSING LAMPS .

1. Verify the forward and rearward facing sensors are not blocked. Sources of blockage can include:
   • stickers, window decals or tags.
   • fold-down screens for TVs or DVD players.
   • non- OEM window tinting.

Were either of the sensors blocked? 

• Yes: If possible, REMOVE the blockage. If the blockage cannot be removed, ADVISE the customer that the blockage will effect the correct operation of the interior auto-dimming mirror.
• No: GO to 3  .

1. Ignition ON.
2. Use a bright lamp to illuminate the forward facing sensor. The mirror should adjust to a high reflectance mode (mirror will be clear).
   Fig 1: Checking Operation Of Interior Auto-Dimming Mirror -- Daylight Conditions

   Courtesy of FORD MOTOR CO.

Does the mirror adjust to the high reflectance (clear) mode? 

• Yes: GO to 4  .
• No: INSTALL a new interior auto-dimming mirror. REFER to Interior Rear View Mirror - Auto-Dimming .

1. Ignition ON.
2. NOTE: Covering the sensor with a finger or hand is not adequate.

   Simulate nighttime conditions with glare:

   • Cover the forward sensor with black electrical tape or other dark material.
   • Illuminate the rearward facing sensor. The mirror should darken to a lower reflectance mode.
   Fig 2: Checking Operation Of Interior Auto-Dimming Mirror - Nighttime Conditions With Glare

   Courtesy of FORD MOTOR CO.

Did the mirror darken to a lower reflectance (darker) mode? 

• Yes: GO to 5  .
• No: GO to  7.

1. Ignition ON.
2. NOTE: Covering the sensor with a finger or hand is not adequate.

   Simulate nighttime conditions without glare by covering the rearward facing sensor. The mirror should adjust to the high reflectance mode.

   Fig 3: Checking Operation Of Interior Auto-Dimming Mirror -- Nighttime Conditions Without Glare

   Courtesy of FORD MOTOR CO.

Did the mirror adjust to the high reflectance (clear) mode? 

• Yes: GO to 6  .
• No: GO to  7.

1. Ignition ON.
2. NOTE: Covering the sensor with a finger or hand is not adequate.

   Simulate nighttime conditions with glare:

   • Cover the forward sensor with black electrical tape or other dark material.
   • Illuminate the rearward facing sensor (mirror should darken at this time).
   Fig 4: Checking Operation Of Interior Auto-Dimming Mirror - Nighttime Conditions With Glare

   Courtesy of FORD MOTOR CO.
3. Select REVERSE.

Did the mirror adjust to a high reflectance (clear) mode? 

• Yes: The system is operating normally at this time. ADVISE the customer of the correct operation of the interior auto-dimming mirror.
• No: GO to 7  .

1. Ignition OFF.
2. Disconnect: Interior Auto-Dimming Mirror.
3. Ignition ON.
4. Measure:

   Interior Auto-Dimming Mirror			Ground
   C911			Ground
   Pin	Circuit	Measurement / Action	Pin	Circuit
   1	CBP38 (GY/BU)		-	Ground

Is the voltage greater than 11 volts? 

• Yes: GO to 8  .
• No: VERIFY that BCM fuse 38 (10A) is OK. If OK, REPAIR the circuit for an open. If not OK, REFER to OEM FUSE AND RELAY INFORMATION and OEM WIRING DIAGRAMS .

1. Ignition OFF.
2. Measure:

   Interior Auto-Dimming Mirror			Ground
   C911			Ground
   Pin	Circuit	Measurement / Action	Pin	Circuit
   4	GD233 (BK)		-	Ground

Is the resistance less than 3 ohms? 

• Yes: GO to 9  .
• No: REPAIR the circuit.

1. Ignition ON.
2. Select REVERSE.
3. Measure:

   Interior Auto-Dimming Mirror			Ground
   C911			Ground
   Pin	Circuit	Measurement / Action	Pin	Circuit
   9	CLS28 (BU/WH)		-	Ground

Is the voltage greater than 11 volts? 

• Yes: INSTALL a new interior auto-dimming mirror. REFER to Interior Rear View Mirror - Auto-Dimming .
• No: REPAIR the circuit.