Code
B1171
HUMMER
B — Body
Body Control Module Communication Fault
Views:
UK: 8
EN: 12
RU: 8
AI status
Completed
Completed
100%
Causes
- Low or intermittent battery voltage or poor battery connection
- Blown fuse or faulty power/relay feeding the BCM
- Poor or corroded ground at the BCM or chassis
- Damaged, chafed, or disconnected communication wiring (CAN/LIN) or connectors
- Water intrusion or corrosion at the BCM connector or harness
- Faulty BCM (internal electronics)
Symptoms
- Instrument panel or DIC (Driver Information Center) shows communication or module warnings
- Some BCM-controlled functions inoperative (locks, lighting, wipers, HVAC, remote keyless)
- Intermittent or permanent electrical gremlins that come and go with vehicle vibration or temperature
- Multiple modules reporting communication-related DTCs
- No response from BCM to a scan tool or intermittent scan tool communication failures
- Vehicle may enter reduced functionality or limp modes for systems relying on BCM messages
What to check
- Connect a capable scan tool and record all DTCs and freeze frame data; note time and conditions of failure
- Confirm battery state of charge and test battery terminals for corrosion and tightness
- Verify fuses and relays for BCM power and accessory supplies are present and good
- Visually inspect BCM and surrounding harness for water damage, corrosion, pinch points, or repairs
- Inspect and wiggle CAN/LIN connectors and harnesses with ignition on while monitoring network for errors (use scope or scan tool bus data)
- Measure BCM supply voltage and ground(s) with a DVOM with ignition ON and key OFF; check for consistent voltage under load
Signal parameters
- Battery voltage at BCM: nominal 12 V (expected 11–14.5 V during normal operation)
- BCM power supply pin(s) present and stable at ignition ON/ACC (within battery range)
- Ground resistance: BCM chassis ground < 0.1–0.2 ohm ideally; continuity to chassis metal good
- CAN bus idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (each referenced to chassis), differential ≈ 0 V at recessive state
- CAN bus dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2.0 V) when messages are driven
- Bus termination resistance between CAN_H and CAN_L ≈ 60 ohms (two 120-ohm terminators in parallel)
Diagnostic algorithm
- Safety first: battery support or stable battery condition recommended when performing extended diagnostics; note anti-theft requirements before disconnecting modules.
- Step 1 — Retrieve codes: Use manufacturer-capable scan tool, record B1171 and any related U/B codes plus freeze frame data and module present/absent lists.
- Step 2 — Verify basics: Check battery state, main power distribution fuses and BCM supply/ignition fuses; repair/replace as needed.
- Step 3 — Inspect connectors/harness: Visually inspect BCM connectors for bent/corroded pins, water intrusion, or heat damage. Repair corrosion or damaged terminals.
- Step 4 — Check grounds and supply: Measure supply voltage and ground continuity at BCM; repair high resistance or intermittent grounds.
- Step 5 — Monitor network: With scan tool and/or oscilloscope monitor CAN_H/CAN_L while operating or while re-creating failure. Look for missing messages, dominant bus-off, voltage shorts, or excessive noise.
- Step 6 — Isolate faults: Disconnect suspect modules or segments to determine if another device is holding the bus dominant or flooding messages. Repair or isolate the offending circuit.
- Step 7 — Repair wiring: If open/short/high-resistance wiring is found, repair with proper connectors and sealing. Replace damaged pigtails or harness sections; solder/heat-shrink or use approved crimp joints.
- Step 8 — Clear codes and retest: After repairs, clear DTCs and verify the fault does not return under the same conditions and that all modules communicate normally.
- Step 9 — BCM replacement/programming: Only replace the BCM after verifying wiring and network health. Install a new or reconditioned BCM and program/configure with manufacturer software per procedure. Verify security/anti-theft relearn steps if required.
- Step 10 — Final verification: Road test to ensure intermittent symptoms are resolved and no further network faults appear; re-scan all modules.
Likely causes
- Corroded BCM connector or pins allowing intermittent contact
- Open or high-resistance ground to BCM
- Shorted or open CANH/CANL wires near BCM or junction points
- Blown fuse or relay supplying BCM memory/power circuits
- Aftermarket accessory tied into body circuits without proper termination causing bus errors
- BCM internal failure following water intrusion or electrical surge
Fault status
Status
BCM detected loss or corruption of communication on the vehicle network. The module has logged a communication fault (B1171) and may report other related network codes. Fault may be intermittent or persistent.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
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Code
B1171
LAND ROVER
B — Body
Handle driver's door internal
Views:
UK: 8
EN: 14
RU: 8
AI status
Completed
Completed
100%
Causes
- Low or intermittent battery voltage or poor battery connection
- Blown fuse or faulty power/relay feeding the BCM
- Poor or corroded ground at the BCM or chassis
- Damaged, chafed, or disconnected communication wiring (CAN/LIN) or connectors
- Water intrusion or corrosion at the BCM connector or harness
- Faulty BCM (internal electronics)
Symptoms
- Instrument panel or DIC (Driver Information Center) shows communication or module warnings
- Some BCM-controlled functions inoperative (locks, lighting, wipers, HVAC, remote keyless)
- Intermittent or permanent electrical gremlins that come and go with vehicle vibration or temperature
- Multiple modules reporting communication-related DTCs
- No response from BCM to a scan tool or intermittent scan tool communication failures
- Vehicle may enter reduced functionality or limp modes for systems relying on BCM messages
What to check
- Connect a capable scan tool and record all DTCs and freeze frame data; note time and conditions of failure
- Confirm battery state of charge and test battery terminals for corrosion and tightness
- Verify fuses and relays for BCM power and accessory supplies are present and good
- Visually inspect BCM and surrounding harness for water damage, corrosion, pinch points, or repairs
- Inspect and wiggle CAN/LIN connectors and harnesses with ignition on while monitoring network for errors (use scope or scan tool bus data)
- Measure BCM supply voltage and ground(s) with a DVOM with ignition ON and key OFF; check for consistent voltage under load
Signal parameters
- Battery voltage at BCM: nominal 12 V (expected 11–14.5 V during normal operation)
- BCM power supply pin(s) present and stable at ignition ON/ACC (within battery range)
- Ground resistance: BCM chassis ground < 0.1–0.2 ohm ideally; continuity to chassis metal good
- CAN bus idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (each referenced to chassis), differential ≈ 0 V at recessive state
- CAN bus dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2.0 V) when messages are driven
- Bus termination resistance between CAN_H and CAN_L ≈ 60 ohms (two 120-ohm terminators in parallel)
Diagnostic algorithm
- Safety first: battery support or stable battery condition recommended when performing extended diagnostics; note anti-theft requirements before disconnecting modules.
- Step 1 — Retrieve codes: Use manufacturer-capable scan tool, record B1171 and any related U/B codes plus freeze frame data and module present/absent lists.
- Step 2 — Verify basics: Check battery state, main power distribution fuses and BCM supply/ignition fuses; repair/replace as needed.
- Step 3 — Inspect connectors/harness: Visually inspect BCM connectors for bent/corroded pins, water intrusion, or heat damage. Repair corrosion or damaged terminals.
- Step 4 — Check grounds and supply: Measure supply voltage and ground continuity at BCM; repair high resistance or intermittent grounds.
- Step 5 — Monitor network: With scan tool and/or oscilloscope monitor CAN_H/CAN_L while operating or while re-creating failure. Look for missing messages, dominant bus-off, voltage shorts, or excessive noise.
- Step 6 — Isolate faults: Disconnect suspect modules or segments to determine if another device is holding the bus dominant or flooding messages. Repair or isolate the offending circuit.
- Step 7 — Repair wiring: If open/short/high-resistance wiring is found, repair with proper connectors and sealing. Replace damaged pigtails or harness sections; solder/heat-shrink or use approved crimp joints.
- Step 8 — Clear codes and retest: After repairs, clear DTCs and verify the fault does not return under the same conditions and that all modules communicate normally.
- Step 9 — BCM replacement/programming: Only replace the BCM after verifying wiring and network health. Install a new or reconditioned BCM and program/configure with manufacturer software per procedure. Verify security/anti-theft relearn steps if required.
- Step 10 — Final verification: Road test to ensure intermittent symptoms are resolved and no further network faults appear; re-scan all modules.
Likely causes
- Corroded BCM connector or pins allowing intermittent contact
- Open or high-resistance ground to BCM
- Shorted or open CANH/CANL wires near BCM or junction points
- Blown fuse or relay supplying BCM memory/power circuits
- Aftermarket accessory tied into body circuits without proper termination causing bus errors
- BCM internal failure following water intrusion or electrical surge
Fault status
Status
BCM detected loss or corruption of communication on the vehicle network. The module has logged a communication fault (B1171) and may report other related network codes. Fault may be intermittent or persistent.
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
Your experience will help others
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