Code
B1681
LAND ROVER
B — Body
the signal from the transceiver module of the theft system is not received
Views:
UK: 4
EN: 9
RU: 12
AI status
Completed
Completed
100%
Causes
- Blown fuse or poor power/ground to the transceiver/antenna module
- Damaged or disconnected antenna, antenna coax, or wiring harness
- Failed transceiver or receiver module
- Lost or faulty communication on vehicle data bus (CAN/LIN) to security module
- Weak or dead key fob/transponder battery or damaged key
- Interference or incorrect frequency RF reception
Symptoms
- Remote keyless entry or immobilizer not operating
- Vehicle fails to recognize key, no remote unlock or start function
- Security/immobilizer warning lamp illuminated or flashing
- Intermittent or permanent inability to start the engine
- No response from keyfob or inconsistent remote range
What to check
- Read all related DTCs and stored freeze/frame data with a factory-level scan tool
- Check battery voltage (vehicle and keyfob) and verify charging system
- Inspect fuses and relay for the theft/transceiver circuit
- Visually inspect transceiver, antenna, and harness connectors for damage or corrosion
- Check for loss of communication errors (CAN/LIN) on scan tool
- Try spare/known-good key or keyfob to confirm key issue vs vehicle
Signal parameters
- Power supply: 9–16 V typical at transceiver supply pin with ignition on
- Ground: low resistance continuity from transceiver ground to chassis
- RF receive frequency: typical keyfob 315 MHz (NA) or 433/434 MHz (EU); receive level should be within expected sensitivity (module dependent)
- Data bus: CAN/LIN messages present on security module network when scanned (no bus errors)
- Key transponder: immobilizer transponder ID and rolling code data expected on module when key presented
Diagnostic algorithm
- Read and note all DTCs, clear codes and attempt to reproduce B1681. Record when/how it returns.
- Verify vehicle battery voltage >12.0 V (engine off) and check charging system with engine running.
- Inspect and test fuses/relays for the theft/transceiver circuit; replace if blown and retest.
- Check power and ground at the transceiver module connector with a DVOM. Repair wiring or grounds that are out of range.
- Visually inspect the antenna(s), coax and connectors for damage, corrosion, or disconnect; repair or reconnect as needed.
- Use a scan tool to check for module presence and communication on the CAN/LIN bus. Diagnose any bus faults (shorts, opens, high resistance).
- Test with a known-good key/keyfob or swap battery in the fob. Attempt re-learn or re‑program procedure per manufacturer instructions.
- If RF reception suspected, check for local RF interference or use RF test equipment or a dealer-level tool to confirm receiver sensitivity (if available).
- If wiring, power, ground and bus comms are good but fault persists, consider replacing or reprogramming the transceiver module following manufacturer procedures.
- After repairs, clear codes and perform full function test (lock/unlock, immobilizer recognition, start) and road test if applicable.
Likely causes
- Fuse for the theft/transceiver module blown or poor ground at module
- Broken antenna cable or connector at the transceiver/receiver
- Transceiver module internal failure
- Key fob battery dead or key not programmed
- CAN or LIN bus open/short or connector corrosion interrupting module messages
- Vehicle module requiring software update or re-flash
Fault status
Status
No signal received from theft system transceiver module — transceiver communication or RF reception fault detected.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
Workshop Manuals
Repair manuals for LAND ROVER
3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop Manual199,00 UAH
Land Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop Manual199,00 UAH
Land Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop Manual199,00 UAH
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Code
B1681
Other
B — Body
PATS Transceiver Module Signal Is Not Received
Views:
UK: 16
EN: 25
RU: 25
AI status
Completed
Completed
100%
Causes
- Blown fuse or poor power/ground to the transceiver/antenna module
- Damaged or disconnected antenna, antenna coax, or wiring harness
- Failed transceiver or receiver module
- Lost or faulty communication on vehicle data bus (CAN/LIN) to security module
- Weak or dead key fob/transponder battery or damaged key
- Interference or incorrect frequency RF reception
Symptoms
- Remote keyless entry or immobilizer not operating
- Vehicle fails to recognize key, no remote unlock or start function
- Security/immobilizer warning lamp illuminated or flashing
- Intermittent or permanent inability to start the engine
- No response from keyfob or inconsistent remote range
What to check
- Read all related DTCs and stored freeze/frame data with a factory-level scan tool
- Check battery voltage (vehicle and keyfob) and verify charging system
- Inspect fuses and relay for the theft/transceiver circuit
- Visually inspect transceiver, antenna, and harness connectors for damage or corrosion
- Check for loss of communication errors (CAN/LIN) on scan tool
- Try spare/known-good key or keyfob to confirm key issue vs vehicle
Signal parameters
- Power supply: 9–16 V typical at transceiver supply pin with ignition on
- Ground: low resistance continuity from transceiver ground to chassis
- RF receive frequency: typical keyfob 315 MHz (NA) or 433/434 MHz (EU); receive level should be within expected sensitivity (module dependent)
- Data bus: CAN/LIN messages present on security module network when scanned (no bus errors)
- Key transponder: immobilizer transponder ID and rolling code data expected on module when key presented
Diagnostic algorithm
- Read and note all DTCs, clear codes and attempt to reproduce B1681. Record when/how it returns.
- Verify vehicle battery voltage >12.0 V (engine off) and check charging system with engine running.
- Inspect and test fuses/relays for the theft/transceiver circuit; replace if blown and retest.
- Check power and ground at the transceiver module connector with a DVOM. Repair wiring or grounds that are out of range.
- Visually inspect the antenna(s), coax and connectors for damage, corrosion, or disconnect; repair or reconnect as needed.
- Use a scan tool to check for module presence and communication on the CAN/LIN bus. Diagnose any bus faults (shorts, opens, high resistance).
- Test with a known-good key/keyfob or swap battery in the fob. Attempt re-learn or re‑program procedure per manufacturer instructions.
- If RF reception suspected, check for local RF interference or use RF test equipment or a dealer-level tool to confirm receiver sensitivity (if available).
- If wiring, power, ground and bus comms are good but fault persists, consider replacing or reprogramming the transceiver module following manufacturer procedures.
- After repairs, clear codes and perform full function test (lock/unlock, immobilizer recognition, start) and road test if applicable.
Likely causes
- Fuse for the theft/transceiver module blown or poor ground at module
- Broken antenna cable or connector at the transceiver/receiver
- Transceiver module internal failure
- Key fob battery dead or key not programmed
- CAN or LIN bus open/short or connector corrosion interrupting module messages
- Vehicle module requiring software update or re-flash
Fault status
Status
No signal received from theft system transceiver module — transceiver communication or RF reception fault detected.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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LAND ROVER 3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
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