B1004
Keep Alive Memory (KAM) Error / ECU Internal Fault
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Code B1004 indicates a Keep Alive Memory (KAM) error in the vehicle's Body Control Module or ECU. Keep Alive Memory is a small amount of power that the vehicle's computer draws from the battery even when the car is off, allowing it to retain learned driving parameters, radio presets, seat positions, and other stored settings. When this memory is interrupted or corrupted, B1004 is set.
This is one of the less alarming body codes. It very commonly appears after a battery has been replaced, disconnected, or has drained completely. In these cases, the code often sets once and may not return after a few normal drive cycles as the system relearns its parameters. However, if the code keeps returning, it may indicate an underlying electrical issue such as a parasitic drain, corroded connections, or a failing BCM.
Start by checking your battery's health—a simple voltage test or load test at any auto parts store (usually free) can confirm whether the battery is the culprit. Clean the terminals and ensure the ground straps are tight. If the battery recently died or was replaced, clear the code and monitor. If it persists, have the BCM inspected professionally. Repairs range from free (clearing a one-time code) to $500 if the BCM needs replacement.
Severity
Symptoms
- •Check engine or service light illuminated
- •Vehicle may lose stored radio presets or seat memory positions
- •Climate control settings may reset to defaults after each start
- •Slight hesitation on startup as ECU relearns parameters
- •Idle may be slightly rough until adaptive values are relearned
- •No major drivability symptoms in most cases
Likely Causes
The Keep Alive Memory requires a constant low-current power supply from the battery. A dead, weak, or disconnected battery causes the KAM to lose its stored data, triggering this code.
Corroded battery terminals, loose ground straps, or damaged connectors at the Body Control Module can interrupt the constant power feed needed to maintain KAM data.
Internal failures in the BCM's memory circuitry can prevent it from retaining learned values and stored calibrations when the ignition is off, setting this code.
Disconnecting the battery for repairs or jump-starting the vehicle can erase KAM data. The code may set once and clear on its own after a few drive cycles as the system relearns.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Test the battery and replace if weak or failing
- Clean and tighten battery terminals and ground connections
- Clear the code and drive several cycles to see if it returns
- Inspect BCM connector for damage or corrosion
- Replace the BCM if the code persists after battery and wiring checks