Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
The car's computer that helps control how power is sent to the wheels has a memory problem. It's like when your video game console can't save your progress because something is wrong with the memory card.
The Transfer Case Control Module (TCCM) uses an EEPROM to store important data. If there's an error, it means the module can't read or write data properly.
The C12A0 code indicates that the Transfer Case Control Module has detected an error in its EEPROM (Electrically Erasable Programmable Read-Only Memory). This memory is used to store configuration and calibration data that the module needs to operate correctly. An error here could mean data corruption or a failure in the memory chip itself.
• 4WD system not functioning properly
• Warning light on the dashboard
• Inability to switch between drive modes
• Corrupted EEPROM data
• Faulty Transfer Case Control Module
• Electrical issues such as poor connections or damaged wiring
EEPROM: A type of memory used in computers and other devices to store small amounts of data that must be saved when power is removed.
TCCM: Transfer Case Control Module, a component that manages the vehicle's 4WD system.
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connections to the TCCM.
• Check for any other related codes that might indicate a broader issue.
• Reprogram or reset the TCCM.
• Replace the TCCM if it is faulty.
• Repair or replace any damaged wiring or connectors.
• OBD-II scanner
• Multimeter
• Screwdriver set
$200 - $800
Moderate
• Chevrolet Silverado
• GMC Sierra
• Dodge Ram
• Regular maintenance checks
• Avoiding harsh driving conditions
• Keeping the vehicle's software updated
Control Module Error
• Have the vehicle inspected by a professional if the 4WD system isn't working.
• Avoid using 4WD until the issue is resolved to prevent further damage.
Check with the vehicle manufacturer for warranty coverage on control modules.
This code has been more prevalent in vehicles with electronic 4WD systems introduced in the early 2000s.
Moderate – It should be addressed soon to ensure proper vehicle operation, especially if 4WD is needed.
Driving with a malfunctioning 4WD system can affect vehicle handling and safety.
• Vehicle in park
• Ignition in the 'on' position
The Transfer Case Control Module is typically located under the dashboard or near the transfer case itself.
Q: Can I drive my vehicle with this code?
A: You can drive, but it's best to avoid using 4WD until the issue is fixed.
Q: Will this code clear itself?
A: No, the issue needs to be diagnosed and repaired for the code to clear.
Pro · Four-system diagnostics
A handheld scanner aimed at engine, transmission, ABS, and airbag diagnostic work.
Chassis and ABS faults usually need a scanner that can read brake-system data directly.
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Useful when reassembly torque matters for wheel, suspension, and under-hood fasteners.
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