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Home >> Mercury >> 2011 >> Grand Marquis V8-4.6L >> Repair and Diagnosis >> Accessories and Optional Equipment >> Antitheft and Alarm Systems >> Testing and Inspection >> Pinpoint Tests >> Pinpoint Test E: DTC B1681

Pinpoint Test E: DTC B1681




Anti-Theft

Pinpoint Tests

Pinpoint Test E: DTC B1681

Refer to Wiring Diagram Set 112, Passive Anti-Theft System for schematic and connector information. Diagrams By Number

Normal Operation

The Passive Anti-Theft System (PATS) transceiver receives voltage from the Central Junction Box (CJB) fuse 24 (10A). The PATS transceiver and the PCM communicate on the transmit (TX) and receive (RX) circuits. The PCM compares the key code stored in memory and enables the starter if the key code is correct.

- DTC B1681 (PATS Transceiver Module Signal Is Not Received) - sets when the PATS transceiver signal is not received by the PCM. This DTC can be caused by circuits to the PATS transceiver, circuits between the PATS transceiver and the PCM, the PATS transceiver or the PCM.

This pinpoint test is intended to diagnose the following:

- Fuse
- PATS key
- PATS transceiver
- Wiring, terminals or connectors
- PCM

PINPOINT TEST E: DTC B1681

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

NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery, Mounting and Cables Battery Disconnect.

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E1 CHECK THE PATS TRANSCEIVER POWER CIRCUIT FOR VOLTAGE


- Ignition OFF.
- Disconnect: PATS Transceiver C2007.
- Ignition ON.
- Measure the voltage between the PATS transceiver C2007-1, circuit 1266 (RD/YE), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
GO to E2.

No
VERIFY the CJB fuse 24 (10A) is OK. If OK, REPAIR the circuit. CLEAR the DTCs. CYCLE the ignition. REPEAT the self-test. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number

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E2 CHECK THE PATS TRANSCEIVER GROUND CIRCUIT FOR AN OPEN


- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the PATS transceiver C2007-2, circuit 676 (PK/OG), harness side and ground.




- Is the resistance less than 5 ohms?

Yes
CONNECT the negative battery cable. GO to E3.

No
REPAIR the circuit. CONNECT the negative battery cable. CLEAR the DTCs. CYCLE the ignition. REPEAT the self-test.

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E3 CHECK THE PATS TRANSCEIVER RECEIVE CIRCUIT FOR VOLTAGE


NOTICE: This pinpoint test step directs testing circuits using a back-probe method. Use the special back-probe tool specified in the tool list. Do not force test leads or other probes into connectors. Adequate care must be exercised to avoid connector terminal damage while ensuring that good electrical contact is made with the circuit or terminal. Failure to follow these instructions may cause damage to wiring, terminals, or connectors and subsequent electrical faults.

- Connect: PATS Transceiver C2007.
- Ignition ON.
- Measure the voltage by backprobing between the PATS transceiver C2007-4, circuit 1216 (GY/OG), harness side and ground.




- Is the voltage greater than 8 volts?

Yes
GO to E7.

No
GO to E4.

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E4 CHECK THE PATS TRANSCEIVER RECEIVE CIRCUIT FOR A SHORT TO GROUND


- Ignition OFF.
- Disconnect: PCM C175b.
- Disconnect: PATS Transceiver C2007.
- Measure the resistance between the PATS transceiver C2007-4, circuit 1216 (GY/OG), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to E5.

No
REPAIR the circuit. CLEAR the DTCs. CYCLE the ignition. REPEAT the self-test. If DTC B1681 is retrieved again, GO to E13.

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E5 CHECK THE PATS TRANSCEIVER RECEIVE CIRCUIT FOR AN OPEN


- Measure the resistance between the PCM C175b-42, circuit 1216 (GY/OG), harness side, and the PATS transceiver C2007-4, circuit 1216 (GY/OG), harness side.




- Is the resistance less than 5 ohms?

Yes
GO to E6.

No
REPAIR the circuit. CLEAR the DTCs. CYCLE the ignition. REPEAT the self-test.

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E6 CHECK THE PATS TRANSCEIVER RECEIVE CIRCUIT FOR A SHORT TO GROUND WITH THE PATS TRANSCEIVER CONNECTED


NOTE: Replacement of the PATS transceiver does not require the PATS keys to be programmed into the PCM again.

- Connect: PATS Transceiver C2007.
- Measure the resistance between the PCM C175b-42, circuit 1216 (GY/OG), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to E13.

No
INSTALL a new PATS transceiver. REFER to Passive Anti-Theft System (PATS) Transceiver Service and Repair. CLEAR the DTCs. CYCLE the ignition. REPEAT the self-test.

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E7 CHECK THE PATS TRANSCEIVER TRANSMIT CIRCUIT FOR VOLTAGE


NOTICE: This pinpoint test step directs testing circuits using a back-probe method. Use the special back-probe tool specified in the tool list. Do not force test leads or other probes into connectors. Adequate care must be exercised to avoid connector terminal damage while ensuring that good electrical contact is made with the circuit or terminal. Failure to follow these instructions may cause damage to wiring, terminals, or connectors and subsequent electrical faults.

NOTE: Replacement of the PATS transceiver does not require the PATS keys to be programmed into the PCM again.

- Measure the voltage by backprobing between the PATS transceiver C2007-3, circuit 1215 (WH/LG), harness side and ground.




- Is the voltage greater than 8 volts?

Yes
INSTALL a new PATS transceiver. REFER to Passive Anti-Theft System (PATS) Transceiver Service and Repair. CLEAR the DTCs. CYCLE the ignition. REPEAT the self-test.

If DTC B1681 is retrieved again, GO to E13.

No
GO to E8.

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E8 CHECK THE PATS TRANSCEIVER TRANSMIT CIRCUIT FOR A SHORT TO GROUND WITH THE PATS TRANSCEIVER CONNECTED


- Ignition OFF.
- Disconnect: PCM C175b.
- Measure the resistance between the PCM C175b-31, circuit 1215 (WH/LG), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to E10.

No
GO to E9.

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E9 CHECK THE PATS TRANSCEIVER TRANSMIT CIRCUIT FOR A SHORT TO GROUND WITH THE PATS TRANSCEIVER DISCONNECTED


NOTE: Replacement of the PATS transceiver does not require the PATS keys to be programmed into the PCM again.

- Disconnect: PATS Transceiver C2007.
- Measure the resistance between the PCM C175b-31, circuit 1215 (WH/LG), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
INSTALL a new PATS transceiver. REFER to Passive Anti-Theft System (PATS) Transceiver Service and Repair. CLEAR the DTCs. CYCLE the ignition. REPEAT the self-test.

No
REPAIR the circuit. CLEAR the DTCs. CYCLE the ignition. REPEAT the self-test.

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E10 CHECK THE PATS TRANSCEIVER TRANSMIT CIRCUIT FOR AN OPEN


- Disconnect: PATS Transceiver C2007.
- Measure the resistance between the PCM C175b-31, circuit 1215 (WH/LG), harness side and the PATS transceiver C2007-3, circuit 1215 (WH/LG), harness side.




- Is the resistance less than 5 ohms?

Yes
GO to E11.

No
REPAIR the circuit. CLEAR the DTCs. CYCLE the ignition. REPEAT the self-test.

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E11 CHECK THE PATS TRANSCEIVER TRANSMIT CIRCUIT FOR VOLTAGE


NOTICE: This pinpoint test step directs testing circuits using a back-probe method. Use the special back-probe tool specified in the tool list. Do not force test leads or other probes into connectors. Adequate care must be exercised to avoid connector terminal damage while ensuring that good electrical contact is made with the circuit or terminal. Failure to follow these instructions may cause damage to wiring, terminals, or connectors and subsequent electrical faults.

NOTE: Replacement of the PATS transceiver does not require the PATS keys to be programmed into the PCM again.

- Connect: PATS Transceiver C2007.
- Connect: PCM C175b.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Trigger the active command TRANSMIT to ON.
- Measure the voltage by backprobing between the PATS transceiver C2007-3, circuit 1215 (WH/LG), harness side and ground.




- Is the voltage less than 5 volts?

Yes
INSTALL a new PATS transceiver. REFER to Passive Anti-Theft System (PATS) Transceiver Service and Repair. CLEAR the DTCs. CYCLE the ignition. REPEAT the self-test.

No
GO to E12.

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E12 CHECK THE PATS TRANSCEIVER TRANSMIT CIRCUIT FOR A SHORT TO VOLTAGE


- Ignition OFF.
- Disconnect: PCM C175b.
- Disconnect: PATS Transceiver C2007.
- Ignition ON.
- Measure the voltage between the PATS transceiver C2007-3, circuit 1215 (WH/LG), harness side and ground.




- Is any voltage indicated?

Yes
REPAIR the circuit. CLEAR the DTCs. CYCLE the ignition. REPEAT the self-test.

No
GO to E13.

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E13 CHECK FOR CORRECT PCM OPERATION


- Disconnect all the PCM connectors.
- Check for:
- corrosion
- damaged pins
- 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 Service and Repair. PROGRAM the PATS keys into the PCM. REFER to Key Programming Using Diagnostic Equipment Key Programming Using Diagnostic Equipment. 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.

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