Pinpoint Test E: DTC B1681 - Passive Anti-Theft System (Pats) Transceiver Signal Is Not Received

WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Use the correct probe adaptor(s) when making measurements. Failure to use the correct probe adaptor(s) may damage the connector.

E1 RETRIEVE THE DIAGNOSTIC TROUBLE CODES (DTCs)
- Enter the following diagnostic mode on the diagnostic tool: Clear PCM Continuous DTCs.
- Key in OFF position.
- Key in ON position.
- Enter the following diagnostic mode on the diagnostic tool: Retrieve the PCM DTCs.
- Is DTC B1681 retrieved?
Yes : GO to E2.

No : The system is OK.
E2 CHECK THE TRANSCEIVER CIRCUIT 1266 (RD/YE) FOR VOLTAGE
- Key in OFF position.
- Disconnect: PATS Transceiver C2007.
- Key in ON position.
- Measure the voltage between the PATS transceiver C2007-1, circuit 1266 (RD/YE), harness side and ground.
  
  Fig 1: Measuring Voltage Between PATS Transceiver C2007-1 And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes : GO to E3.

No : VERIFY the CJB fuse 24 (10A) is OK. If OK, REPAIR the circuit. CLEAR the DTCs. TEST the system for normal operation.
E3 CHECK THE PATS TRANSCEIVER GROUND CIRCUIT 676 (PK/OG) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the PATS transceiver C2007-2, circuit 676 (PK/OG), harness side and ground.
  
  Fig 2: Measuring Resistance Between PATS Transceiver C2007-2 And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to E4.

No : REPAIR the circuit. CLEAR the DTCs. TEST the system for normal operation.
E4 CHECK THE PATS RECEIVER CIRCUIT 1216 (GY/OG) FOR VOLTAGE
- Connect: PATS Transceiver C2007.
- Key in ON position.
- Measure the voltage by backprobing between the PATS transceiver C2007-4, circuit 1216 (GY/OG), harness side and ground.
  
  Fig 3: Measuring Voltage Between PATS Transceiver C2007-4 And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 9 volts?
Yes : GO to E6.

No : GO to E5.
E5 HECK THE PATS RECEIVER CIRCUIT 1216 (GY/OG) FOR A SHORT TO GROUND
- Key in OFF position.
- Disconnect: PATS Transceiver C2007.
- Measure the resistance between PATS transceiver C2007-4, circuit 1216 (GY/OG), harness side and ground.
  
  Fig 4: Measuring Resistance Between PATS Transceiver C2007-4 And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes : GO to E6.

No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. If the system fails again, GO to E13.
E6 CHECK THE PATS RECEIVER CIRCUIT 1216 (GY/OG) FOR AN OPEN
- Key in OFF position.
- Disconnect: PATS Transceiver C2007.
- Disconnect: PCM C175b.
- Measure the resistance between the PATS transceiver C2007-4, circuit 1216 (GY/OG), harness side and the PCM C175b-42, circuit 1216 (GY/OG), harness side.
  
  Fig 5: Checking The PATS Receiver Circuit 1216 (GY/OG) For An Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to E7.

No : REPAIR the circuit. CLEAR the DTCs. TEST the system for normal operation.
E7 CHECK THE PATS TRANSMIT CIRCUIT 1215 (WH/LG) FOR VOLTAGE
- Key in OFF position.
- Connect: PATS Transceiver C2007.
- Connect: PCM C175b.
- Key in ON position.
- Measure the voltage by backprobing between the PATS transceiver C2007-3, circuit 1215 (WH/LG), harness side and ground.
  
  Fig 6: Measuring Voltage Between PATS Transceiver C2007-3 And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 9 volts?
Yes : GO to E11.

No : GO to E8.
E8 CHECK THE PATS TRANSMIT CIRCUIT 1215 (WH/LG) FOR A SHORT TO GROUND WITH THE TRANSCEIVER CONNECTED
- Key in OFF position.
- Disconnect: PCM C175b.
- Measure the resistance between the PCM C175b-22, circuit 1215 (WH/LG), harness side and ground.
  
  Fig 7: Measuring Resistance Between PCM C175b-22 Circuit 1215 Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes : GO to E10.

No : GO to E9.
E9 CHECK THE PATS TRANSMIT CIRCUIT 1215 (WH/LG) FOR A SHORT TO GROUND WITH THE TRANSCEIVER DISCONNECTED
- Disconnect: PATS Transceiver C2007.
- Measure the resistance between PATS transceiver C2007-3, circuit 1215 (WH/LG), harness side and ground.
  
  Fig 8: Measuring Resistance Between PATS Transceiver C2007-3 And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes : INSTALL a new PATS transceiver. REFER to PASSIVE ANTI-THEFT SYSTEM (PATS) TRANSCEIVER . CLEAR the DTCs. REPEAT the self-test.

No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
E10 CHECK THE PATS TRANSMIT CIRCUIT 1215 (WH/LG) FOR AN OPEN
- Disconnect: PATS Transceiver C2007.
- Measure the resistance between the PATS transceiver C2007-3, circuit 1215 (WH/LG), harness side and the PCM C175b-22, circuit 1215 (WH/LG), harness side.
  
  Fig 9: Measuring Resistance Between PATS Transceiver C2007-3 Circuit 1215 Harness Side And PCM C175b-22
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to E13.

No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
E11 CHECK THE TRANSCEIVER TRANSMIT CIRCUIT 1215 (WH/LG) FOR VOLTAGE
- Key in ON position.
- Enter the following diagnostic mode on the diagnostic tool: PCM ACTIVE COMMAND.
- Select the TRANSMIT SIGNAL command.
- Trigger RF to ON.
- Measure the voltage by backprobing between the PATS transceiver C2007-3, circuit 1215 (WH/LG), harness side and ground.
  
  Fig 10: Measuring Voltage Between PATS Transceiver C2007-3 And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage less than 5 volts?
Yes : INSTALL a new PATS transceiver. REFER to PASSIVE ANTI-THEFT SYSTEM (PATS) TRANSCEIVER . CLEAR the DTCs. REPEAT the self-test.

No : GO to E12.
E12 CHECK THE PATS TRANSCEIVER TRANSMIT CIRCUIT 1215 (WH/LG) FOR A SHORT TO BATTERY
- Key in OFF position.
- Disconnect: PCM C175b.
- Disconnect: PATS Transceiver C2007.
- Key in ON position.
- Measure the voltage between the PATS transceiver C2007-3, circuit 1215 (WH/LG), harness side and ground.
  
  Fig 11: Measuring Voltage Between PATS C2007-3 Circuit 1215 Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is voltage present?
Yes : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.

No : GO to E13.
E13 CHECK FOR CORRECT PCM OPERATION
NOTE: When a new PCM is installed, the encoded ignition keys must be programmed.
- Disconnect all the PCM connectors.
- Check for:
  - corrosion
  - pushed-out pins
- Connect all the PCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes : INSTALL a new PCM. REFER to ELECTRONIC ENGINE CONTROLS .

PROGRAM the encoded ignition keys. REFER to KEY PROGRAMMING USING DIAGNOSTIC EQUIPMENT . 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.