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Home >> Mercury >> 1998 >> Grand Marquis V8-281 4.6L SFI >> Repair and Diagnosis >> Accessories and Optional Equipment >> Antitheft and Alarm Systems >> Testing and Inspection >> Diagnostic Trouble Code Tests and Associated Procedures >> B Code Charts >> B1681: PATS Transceiver Signal Is Not Received

B1681: PATS Transceiver Signal Is Not Received

B1681-1 Retrieve The DTCs
- Key OFF.
- Connect NGS to DLC.
- Retrieve and document continuous DTCs.
- Clear continuous DTCs.
- Perform PATS on-demand self-test.
Is DTC B1681 retrieved?
Yes
Go to B1681-2.
No
System is OK.

B1681-2 Check The PATS Transceiver For Voltage - Circuit 1266 (R/Y)
- Key OFF.
- Disconnect PATS transceiver C204.
- Key ON.
- Measure the voltage between PATS transceiver C204, circuit 1266 (R/Y), and ground.
Is the voltage greater than 10 volts?
Yes
Go to B1681-3.
No
- REPAIR circuit 1266 (R/Y).
- CLEAR the DTCs.
- Test the system for normal operation.

B1681-3 Check The PATS Transceiver Ground - Circuit 1267 (BK/Y)
- Key OFF.
- Measure the resistance between PATS transceiver C204, circuit 1267 (BK/Y), and ground.
Is the resistance less than 5 ohms?
Yes
Go to B1681-4.
No
- REPAIR circuit 1267 (BK/Y).
- CLEAR the DTCs.
- TEST the system for normal operation.

B1681-4 Check The PATS Transceiver Receive Circuit For Voltage - Circuit 1216 (GY/O)
- Reconnect PATS transceiver C204.
- Key ON.
- Measure the voltage by back probing between PATS transceiver C204, circuit 1216 (GY/O), and ground.
Is the voltage greater than 9 volts?
Yes
Go to B1681-6.
No
Go to B1681-5.

B1681-5 Check The PATS Transceiver Receive Circuit For Short - Circuit 1216 (GY/O)
- Key OFF.
- Disconnect PATS transceiver C204.
- Measure the resistance between PATS transceiver C204, circuit 1216 (GY/O), and ground.
Is the resistance greater than 100 ohms?
Yes
Go to B1681-6.
No
- CHECK circuit 1216 (GY/O) for short to ground.
If OK:
- REPLACE the Passive Anti-Theft System (PATS) Control Module. Service and Repair
- CYCLE the ignition to RUN using two encoded ignition keys.
- Go to Pinpoint Test B2139. B2139: PCM ID Does Not Match Between PATS and PCM
- CLEAR the DTCs.
- TEST the system for normal operation.
If the circuit is not OK,
- REPAIR circuit 1216 (GY/O).
- CLEAR the DTCs.
- TEST the system for normal operation.

B1681-6 Check Circuit For Open
- Measure the resistance between PATS transceiver C241, circuit 168 (R/BK), and PATS module C242, circuit 168 (R/BK).
Is the resistance less than 5 ohms?
Yes
Go to B1681-7.
No
- REPAIR circuit 168 (R/BK).
- CLEAR the DTCs.
- TEST the system for normal operation.

B1681-7 Check The PATS Transceiver Transmit Circuit For Voltage - Circuit 1215 (W/LG)
- Key OFF.
- Reconnect PATS transceiver C204.
- Key ON.
- Measure the voltage by back probing between PATS transceiver C204, circuit 1215 (W/LG), and ground.
Is the voltage greater than 9 volts?
Yes
Go to B1681-9.
No
Go to B1681-8.

B1681-8 Check The PATS Transceiver Transmit Circuit For Open - Circuit 1215 (W/LG)
- Key OFF.
- Disconnect PATS transceiver C204.
- Measure the resistance between PATS transceiver C204, circuit 1215 (W/LG), and ground.
Is the resistance greater than 100 ohms?
Yes
Go to B1681-9.
No
- CHECK circuit 1215 (W/LG) for short to ground.
If OK:
- REPLACE the Passive Anti-Theft System (PATS) Control Module. Service and Repair
- CYCLE the ignition to RUN using two encoded ignition keys.
- Go to Pinpoint Test B2139. B2139: PCM ID Does Not Match Between PATS and PCM
- CLEAR the DTCs.
- TEST the system for normal operation.
If the circuit is not OK:
- REPAIR circuit 1215 (W/LG).
- CLEAR the DTCs.
- TEST the system for normal operation.

B1681-9 Check The PATS Transmit Circuit For Proper Operation - Circuit 1216 (GY/O)
- Reconnect PATS transceiver C204.
- Key ON.
- Trigger the PATS active command TRANSMIT SIGNAL COMMAND to ON. PATS Active Command Index
- Measure the voltage by back probing between PATS transceiver C204, circuit 1216 (GY/O), and ground.
Does the voltage drop from greater than 9 volts to less than 1 volt when the active command is triggered ON?
Yes
Go to B1681-10.
No
- CHECK circuit 1216 (GY/O) for continuity to PATS module C229.
If OK:
- REPLACE the Passive Anti-Theft System (PATS) Control Module. Service and Repair
- CYCLE the ignition to RUN using two encoded ignition keys.
- Go to Pinpoint Test B2139. B2139: PCM ID Does Not Match Between PATS and PCM
- CLEAR the DTCs.
- TEST the system for normal operation.
If the circuit is not OK:
- REPAIR circuit 1216 (GY/O).
- CLEAR the DTCs.
- TEST the system for normal operation.

B1681-10 Check The PATS System With New PATS Transceiver
- Key OFF.
- Replace the PATS transceiver. Service and Repair
- Key ON.
- Perform the PATS on-demand self-test.
Is DTC B1681 retrieved?
Yes
Go to B1681-11.
No
System is OK.

B1681-11 Check The PATS System With New PATS Module
- Key OFF.
- Replace the Passive Anti-Theft System (PATS) Control Module. Service and Repair
- Cycle the ignition to RUN using two encoded ignition keys.
- Go to Pinpoint Test B2139. B2139: PCM ID Does Not Match Between PATS and PCM
- Clear the DTC(s).
Test the system for normal operation.
- Key ON.
- Perform the PATS on-demand self-test.
Is DTC B1681 retrieved?
Yes
- REPAIR circuit 1266 (R/Y), 1267 (BK/Y), 1215 (W/LG), and 1216 (GY/O).
- CLEAR the DTCs.
- TEST the system for normal operation.
No
- If no DTCs are retrieved, the system is OK.
- If other DTCs are retrieved, REFER to PATS Diagnostic Trouble Code (DTC) Index. PATS Diagnostic Trouble Code (DTC) Index
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