Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSDODGE AND RAM2006MAGNUM V6-2.7L VIN TREPAIR AND DIAGNOSISA L L DIAGNOSTIC TROUBLE CODES ( DTC )TESTING AND INSPECTIONU CODE CHARTSU0121POWERTRAIN
2006 Dodge and Ram Magnum V6-2.7L VIN T
Powertrain
2006 Dodge and Ram Magnum V6-2.7L VIN TSECTION Powertrain
U0121-LOST COMMUNICATION WITH ANTI-LOCK BRAKE MODULE
WHEN MONITORED
Ignition run time is greater than 1 second. Battery voltage between 9 and 16 volts. Engine run time greater than 3 seconds.
SET CONDITION
The PCM doesn't receive an ABS message over the CAN C circuit for 7 consecutive seconds. The circuit is continuously monitored.
POSSIBLE CAUSES
- CAN C BUS failure open or shorted condition
- ABS module
- PCM
Refer to Body Control Systems for diagnostic procedures and for further possible causes.
Diagnostic Test
1. ACTIVE DTC
Ignition on, engine not running.
With a scan tool, read PCM DTCs.
Q: Is the DTC active at this time?
YES: Refer to Body Control Systems for diagnostic procedures and for further possible causes.
NO: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
U0121-Lost Communication With Anti-lock Brake Module:
WHEN MONITORED
Ignition run time is greater than 1 second. Battery voltage between 9 and 16 volts. Engine run time greater than 3 seconds.
SET CONDITION
The PCM doesn't receive an ABS message over the CAN C circuit for 7 consecutive seconds. The circuit is continuously monitored.
POSSIBLE CAUSES
- CAN C BUS failure open or shorted condition
- ABS module
- PCM
Refer to Body Control Systems for diagnostic procedures and for further possible causes.
Diagnostic Test
1. ACTIVE DTC
Ignition on, engine not running.
With a scan tool, read PCM DTCs.
Q: Is the DTC active at this time?
YES: Refer to Body Control Systems for diagnostic procedures and for further possible causes.
NO: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.