Possible Causes

WARNING: This page is about a different car, the 2005 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.

Circuit 1441 (WH/LG) short to voltage
Circuit 1442 (DG/WH) short to voltage
Circuit 1443 (WH/LB) short to voltage
Circuit 1444 (DB/YE) short to voltage
Parking aid sensor
Parking aid bumper harness
Parking aid module

D1 CHECK THE RECORDED DTCS FROM BOTH THE CONTINUOUS AND ON-DEMAND PARKING AID MODULE SELF-TESTS
- Check the recorded parking aid module DTCs from the continuous and on-demand self-tests.
- Are any DTCs recorded?
- Yes : If multiple DTCs are recorded, GO to D2.
  For DTCs, C1699, C1702, C1705 and C1708, GO to D3.
  
  All others, REFER to the PARKING AID MODULE DIAGNOSTIC TROUBLE CODE (DTC) INDEX .
- No : GO to PINPOINT TEST B .
D2 CHECK THE BUMPER WIRING HARNESS
- Inspect the bumper wiring harness for opens, shorts, grounds, or corrosion.
- Is the bumper harness OK?
- Yes : GO to D3.
- No : REPAIR or INSTALL a new bumper wiring harness. REPEAT the self-test.

D3 CHECK THE SENSOR CIRCUITRY FOR SHORTS TO VOLTAGE

Key in OFF position.
Disconnect: Suspect Parking Aid Sensor.
Disconnect: Parking Aid Module C2023.
Key in ON position.

Measure the voltage between the suspect parking aid sensor pin 2, harness side and ground as follows:

Fig 1: Checking Sensor Circuitry For Shorts To Voltage

Courtesy of FORD MOTOR CO.

REAR SENSORS, CONNECTOR PINS & CIRCUIT

DTC	Sensor	Sensor Connector - Pin	Circuit
C1699	LH Outer	C4009-2	1441 (WH/LG)
C1702	RH Outer	C4011-2	1444 (DB/YE)
C1705	LH Inner	C4010-2	1442 (DG/WH)
C1708	RH Inner	C4012-2	1443 (WH/LB)

Is any voltage present?

Yes : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
No : GO to D4.

D4 CHECK THE PARKING AID SENSORS
- Install a known good parking aid sensor(s) for each of the suspect parking aid sensor(s).
- Clear all the DTCs.
- Test the system for normal operation.
- Is the concern still present?
- Yes : GO to D5.
- No : INSTALL a new parking aid sensor. REFER to PARKING AID SENSOR . CLEAR the DTCs. REPEAT the self-test.
D5 CHECK FOR CORRECT PARKING AID MODULE OPERATION
- Disconnect the parking aid module connector.
- Check for:
  - Corrosion
  - Pushed-out pins
- Connect the parking aid module connector and make sure it seats correctly.
- Operate the system and determine if the concern is still present.
- Is the concern still present?
- Yes : INSTALL a new parking aid module. REFER to PARKING AID MODULE . CLEAR the DTCs. REPEAT the self-test.
- No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.