Code
B1558
HUMMER
B — Body
BCM EPROM Checksum Error
AI status
Completed
Completed
100%
Causes
- Corrupted BCM EPROM/EEPROM contents (program/data corruption)
- Interrupted programming or failed reflash
- Low or erratic battery/charging voltage (voltage spike or brownout)
- Water intrusion or physical damage to BCM or connector
- Poor ground or power supply to the BCM
- Aftermarket device installation (alarms, remote start) interfering with BCM memory
Symptoms
- One or more body systems (locks, lights, wipers, interior features) operate intermittently or erratically
- Multiple body control related DTCs or communication DTCs present
- Warning lights on dash related to body modules or message center notifications
- Vehicle may go into limited functionality or limp mode for affected systems
- Failure to program/reprogram BCM or repeated reoccurrence of the same code after clear
What to check
- Read all DTCs and freeze frame data with a capable scan tool; note related U- or B- codes
- Check battery state-of-charge and charging system (measure VBAT at BCM with engine off and running)
- Inspect BCM connectors for corrosion, bent pins, water entry, or physical damage
- Verify solid battery negative and chassis grounds at BCM and engine
- Scan CAN bus for communication faults and verify module presence on network
- Review vehicle service history for recent programming, battery disconnect, or aftermarket installs
Signal parameters
- Battery voltage (VBAT) at the BCM
- BCM supply/ignition voltages (IGN 1/IGN 2)
- CAN bus message activity and error counters
- Module Alive/Present status on scanner
- Stored checksum value vs calculated checksum (if available on scan tool)
- Number and type of memory/fault counters reported by BCM
Diagnostic algorithm
- Verify and record DTCs and freeze frame data. Check for related communication codes (U-codes) and other body module codes.
- Ensure battery is fully charged and connections are clean/tight. Test charging system to rule out supply issues.
- Visually inspect BCM and harness: look for water intrusion, corrosion, damaged pins, or signs of overheating.
- Verify grounds: measure resistance between BCM ground and battery negative; repair any high-resistance connections.
- Check CAN bus for proper termination and activity; repair wiring or short/open faults found.
- If hardware and wiring are good, attempt to clear code and reflash/program BCM with the latest OEM calibration following factory procedure. Use an OEM-capable scanner/programmer and ensure stable power during update (battery charger where specified).
- After reflash, confirm the checksum/code cleared and exercise vehicle functions. Re-scan for reoccurrence.
- If reprogramming fails or the checksum error returns, consider BCM replacement. When replacing, follow OEM procedures for cloning or programming VIN, immobilizer, and body configuration data; restore any stored settings as required.
- After repair or replacement, perform a full system scan and road test to confirm normal operation and no return of the DTC.
Likely causes
- Battery disconnected or voltage drop during a BCM reflash or update
- Failed or partially erased EEPROM inside the BCM
- CAN bus errors preventing proper checksum verification
- Electrical surge or transient event damaged module memory
- Loose or corroded BCM power/ground connector
Fault status
Status
BCM detected an EPROM/EEPROM checksum error — module configuration or calibration data is corrupted or unreadable.
Repair difficulty: Medium
Diagnostic time: 1.5-3.0 hours
Similar codes
Repair manuals
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138
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