Pinpoint Test C: DTCs C1742 - Rear Sounder Circuit Failure and C1743 - Rear Sounder Circuit Short To Vbatt

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Parking Aid for schematic and connector information.

Normal Operation 

With the ignition switch in the RUN position, and the gear selector in REVERSE (R), the parking aid system calculates the distance to an object by the use of a radar sensor. A variable-rate warning tone is generated by the parking aid speaker. The speaker increases its warning tone rate as the vehicle gets closer to an obstacle. When an object is detected within 45.7 cm (18 in) of the vehicle, the warning tone becomes continuous. Voltage is supplied from the parking aid module (PAM) to the parking aid speaker through circuit 1437 (BK/PK). The parking aid speaker is grounded through circuit 676 (PK/OG). The parking aid speaker is part of the high mounted stoplamp.

• DTC C1742 (Rear Sounder Circuit Failure) - is a continuous and on-demand DTC that sets if the PAM detects a short to ground on the parking aid speaker circuit 1437 (BK/PK) when the vehicle is in REVERSE (R).
• DTC C1743 (Rear Sounder Circuit Short to Vbatt) - is a continuous and on-demand DTC that sets if the PAM detects a short to voltage on the parking aid speaker circuit 1437 (BK/PK) when the vehicle is not in REVERSE (R).

This pinpoint test is intended to diagnose the following:

• Wiring, terminals or connectors
• Parking aid system inline harness
• Parking aid speaker (part of high mounted stoplamp)
• PAM

PINPOINT TEST C: DTCs C1742 - REAR SOUNDER CIRCUIT FAILURE AND C1743 - REAR SOUNDER CIRCUIT SHORT TO VBATT 

1. C1 CHECK THE RECORDED DTCs FROM BOTH THE CONTINUOUS AND ON-DEMAND PAM SELF-TESTS 
   • Check the recorded DTCs from the PAM self-test.
   • Are any DTCs recorded? 
   1. YES  : For DTC C1742 or C1743, go to  C2.

      For all other DTCs, REFER to DTC Index .

   2. NO  : Go to Pinpoint Test A .
2. C2 RETRIEVE THE RECORDED DTCs FROM BOTH THE CONTINUOUS AND ON-DEMAND PAM SELF-TESTS 
   • Key in OFF position.
   • Disconnect: High Mounted Stoplamp C904
   • Key in ON position.
   • Retrieve the recorded PAM DTCs from the on-demand self-test.
   • Are any DTCs recorded? 
   1. YES  : For DTC C1742, go to  C3.

      For DTC C1743, go to  C4.

      For all other DTCs, REFER to DTC Index .

   2. NO  : INSTALL a new high mounted stoplamp. REFER to EXTERIOR LIGHTING article. CLEAR the DTCs. REPEAT the self-test.
3. C3 CHECK CIRCUIT 1437 (BK/PK) FOR A SHORT TO GROUND 
   • Key in OFF position.
   • Disconnect: Parking Aid System Inline Harness C406
   Fig 1: Checking Circuit For Short To Ground
   Courtesy of FORD MOTOR CO.
   • Measure the resistance between the parking aid system inline harness C406-7, circuit 1437 (BK/PK), body harness side and ground.
   • Is the resistance less than 5 ohms? 
   1. YES  : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
   2. NO  : Go to  C5.
4. C4 CHECK CIRCUIT 1437 (BK/PK) FOR A SHORT TO VOLTAGE 
   • Key in OFF position.
   • Disconnect: Parking Aid System Inline Harness C406
   • Key in ON position.
   Fig 2: Checking Circuit For Short To Voltage
   Courtesy of FORD MOTOR CO.
   • Measure the voltage between the parking aid system inline harness C406-7, circuit 1437 (BK/PK), body harness side and ground.
   • Is there any voltage indicated? 
   1. YES  : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
   2. NO  : Go to  C5.
5. C5 CHECK THE PARKING AID SYSTEM INLINE HARNESS 
   • Inspect the parking aid system inline harness for an open, short to voltage, or short to ground.
   • Is the parking aid system inline harness OK? 
   1. YES  : Go to  C6.
   2. NO  : INSTALL a new or REPAIR the parking aid system inline harness. CLEAR the DTCs. REPEAT the self-test.
6. C6 CHECK FOR CORRECT PAM OPERATION 
   • Disconnect the PAM connector.
   • Check for:
     • corrosion
     • damaged pins
     • pushed-out pins
   • Connect the PAM connector and make sure it seats correctly.
   • Operate the system and determine if the concern is still present.
   • Is the concern still present? 
   1. YES  : INSTALL a new PAM. REFER to Parking Aid Module (PAM) . TEST the system for normal operation.
   2. 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.