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Home >> Mercury >> 2009 >> Milan AWD L4-2.3L >> Repair and Diagnosis >> Accessories and Optional Equipment >> Antitheft and Alarm Systems >> Testing and Inspection >> Pinpoint Tests >> Anti-Theft - Passive Anti-Theft System (PATS) >> 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 Smart Junction Box (SJB) on circuit CBP18 (GY/OG) and is grounded on circuit GD116 (BK/VT). The PATS transceiver and the Instrument Cluster (IC) communicate on the TX and RX circuits VRT23 (VT/GY) and VRT24 (YE/OG). The IC compares the key code stored in memory and sends a message to the PCM to enable the starter and fuel injectors 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 IC. This DTC can be caused by circuits between the PATS transceiver and the IC, or circuits to the PATS transceiver. This can also be caused by using the incorrect PATS transceiver part number.

This pinpoint test is intended to diagnose the following:

- Fuse
- Wiring, terminals or connectors
- PATS transceiver
- IC



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.

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E1 CHECK THE PATS TRANSCEIVER POWER CIRCUIT CBP18 (GY/OG) FOR VOLTAGE


- Ignition OFF.
- Disconnect: PATS Transceiver C252.
- Ignition ON.
- Measure the voltage between the PATS transceiver C252-1, circuit CBP18 (GY/OG), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
GO to E2.

No
VERIFY the SJB fuse 26 (7.5A) 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.

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E2 CHECK THE PATS TRANSCEIVER GROUND CIRCUIT GD116 (BK/VT) FOR AN OPEN


- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the PATS transceiver C252-2, circuit GD116 (BK/VT), harness side and ground.




- Is the resistance less than 5 ohms?

Yes
GO to E3.

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

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E3 CHECK THE PATS TRANSCEIVER RECEIVE CIRCUIT VRT24 (YE/OG) FOR VOLTAGE


- Connect: PATS Transceiver C252.
- Connect: Negative Battery Cable.
- Ignition ON.
- Measure the voltage by backprobing between the PATS transceiver C252-3, circuit VRT24 (YE/OG), harness side and ground.




- Is the voltage greater than 8 volts?

Yes
GO to E6.

No
GO to E4.

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E4 CHECK THE PATS TRANSCEIVER RECEIVE CIRCUIT VRT24 (YE/OG) FOR A SHORT TO GROUND


- Ignition OFF.
- Disconnect: IC C220.
- Disconnect: PATS Transceiver C252.
- Measure the resistance between the PATS transceiver C252-3, circuit VRT24 (YE/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 E12.

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E5 CHECK THE PATS TRANSCEIVER RECEIVE CIRCUIT VRT24 (YE/OG) FOR AN OPEN


- Measure the resistance between the IC C220-4, circuit VRT24 (YE/OG), harness side and the PATS transceiver C252-3, circuit VRT24 (YE/OG), harness side.




- Is the resistance less than 5 ohms?

Yes
GO to E12.

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

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E6 CHECK THE PATS TRANSCEIVER TRANSMIT CIRCUIT VRT23 (VT/GY) FOR VOLTAGE


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

- Measure the voltage by backprobing between the PATS transceiver C252-4, circuit VRT23 (VT/GY), 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 E12.

No
GO to E7.

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E7 CHECK THE PATS TRANSCEIVER TRANSMIT CIRCUIT VRT23 (VT/GY) FOR A SHORT TO GROUND WITH THE PATS TRANSCEIVER CONNECTED


- Ignition OFF.
- Disconnect: IC C220.
- Measure the resistance between the IC C220-3, circuit VRT23 (VT/GY), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to E9.

No
GO to E8.

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E8 CHECK THE PATS TRANSCEIVER TRANSMIT CIRCUIT VRT23 (VT/GY) 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 IC again.

- Disconnect: PATS Transceiver C252.
- Measure the resistance between the IC C220-3, circuit VRT23 (VT/GY), 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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E9 CHECK THE PATS TRANSCEIVER TRANSMIT CIRCUIT VRT23 (VT/GY) FOR AN OPEN


- Disconnect: PATS Transceiver C252.
- Measure the resistance between the IC C220-3, circuit VRT23 (VT/GY), harness side and the PATS transceiver C252-4, circuit VRT23 (VT/GY), harness side.




- Is the resistance less than 5 ohms?

Yes
GO to E10.

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 VRT23 (VT/GY) FOR VOLTAGE


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

- Connect: PATS Transceiver C252.
- Connect: IC C220.
- Connect the scan tool.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger.
- Trigger the IC active command "Transmit" to on.
- NOTE: The IC may only supply the signal voltage momentarily. It is important to monitor the meter while triggering the active command on.
- Measure the voltage by backprobing between the PATS transceiver C252-4, circuit VRT23 (VT/GY), harness side and ground.




- Does the voltage drop momentarily, then come back to normal?

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 E11.

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E11 CHECK THE PATS TRANSCEIVER TRANSMIT CIRCUIT VRT23 (VT/GY) FOR A SHORT TO VOLTAGE


- Ignition OFF.
- Disconnect: IC C220.
- Disconnect: PATS Transceiver C252.
- Ignition ON.
- Measure the voltage between the PATS transceiver C252-4, circuit VRT23 (VT/GY), 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 E12.

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E12 CHECK FOR CORRECT IC OPERATION


- Disconnect the IC connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the IC connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new IC. REFER to Instrument Panel, Gauges and Warning Indicators. RESET the parameters in both the IC and the PCM. REFER to Passive Anti-Theft System (PATS) Parameter Reset Passive Anti-Theft System (PATS). PROGRAM the PATS keys into the new IC. REFER to Integrated Keyhead Transmitter (IKT) Key Programming Using Diagnostic Equipment 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. CLEAR the DTCs. CYCLE the ignition. REPEAT the self-test.

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