B0611

Code

Generic B — Body

Body Control Module CAN Message Timeout

Brand: Generic

Type: B — Body

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Page language: EN

Open, shorted or corroded CAN wiring or connectors between BCM and other module(s)
Faulty CAN transceiver or BCM internal circuitry
Faulty or unpowered sending module (downstream module not sending messages)
Missing or incorrect bus termination (open or shorted 120 Ω resistors)
Poor battery power, poor ground or intermittent supply to BCM or sending module
High bus error rate or bus-off condition caused by another node

Loss or intermittent operation of BCM-controlled features (lights, locks, windows, convenience features)
Warning or indicator lamps on dash related to body electronics
Multiple communication-related DTCs stored in BCM or other modules
Delayed or no response to switch inputs for functions tied to the missing message
Possible no-crank or immobilizer-related symptoms if security messages are missing

Read and record all stored DTCs and freeze frame data from BCM and other modules
Verify battery voltage and main power/ground at BCM and suspected sender module
Visually inspect CAN connectors, pinned terminals, and harness for damage or corrosion
Scan tool: monitor CAN messages and verify the expected message IDs and periodicity
Measure CAN_H and CAN_L voltages with key on engine off (KOEO) and observe idle voltages
Check CAN bus termination resistance across CAN_H and CAN_L (~60 Ω total) with power off

CAN_H idle ≈ 2.5 V, CAN_L idle ≈ 2.5 V; differential ~0 V when recessive
Dominant state: CAN_H rises (~3.5 V) and CAN_L falls (~1.5 V); differential ~2 V
Total bus termination ≈ 60 Ω across CAN_H and CAN_L (two 120 Ω in parallel)
Common bus speeds: 125 kbps, 250 kbps, 500 kbps (verify vehicle-specific rate with scan tool)
Typical message periods vary by signal (10–1000 ms); timeout is usually several message periods (vehicle-specific)

Connect a professional scan tool and record all current and pending DTCs and freeze frame data from BCM and other modules.
Confirm the BCM is receiving power and ground; verify battery voltage at BCM connector with key on.
Monitor the CAN bus with the scan tool — check for the specific message(s) that timed out and note their expected IDs and frequency.
With the tool monitoring messages, perform a visual/wiggle test of wiring and connectors for the BCM and the suspected sender module while watching for dropped messages or errors.
Measure CAN_H and CAN_L idle voltages and observe differential with a scope if available; verify termination resistance (~60 Ω) with power off.
If bus errors are present (error counters, bus-off), isolate by disconnecting non-essential nodes one at a time to find the faulty node or short.
If a specific sending module is not transmitting, verify its supply and ground, check its inputs/sensors, and perform module-level diagnostics; replace or reprogram if confirmed faulty.
Repair any wiring/connectors found damaged or corroded. Replace faulty CAN transceiver or BCM if bench-tested and confirmed defective.
After repairs, clear DTCs and perform a function and road test while monitoring the bus to ensure no recurrence.
If no hardware fault is found, check for available software updates or reflash procedures from manufacturer and perform as directed.