2006 Grand Cherokee Laredo ABS Fault: U0121 OBD2 Code Explained
My 2006 Grand Cherokee Laredo has a Check Engine light, ABS light, and parking light illuminated. The diagnostic trouble code displayed is U0121. This indicates a communication failure between the ABS module and the Body Control Module (BCM) via the Bus system. I'm looking for guidance on how to diagnose and resolve this issue. Any insights or troubleshooting steps would be greatly appreciated.
No other error codes or symptoms reported? Has there been any recent modifications, such as an aftermarket remote start system? This could prevent the ABS module from receiving proper power and thus fail to communicate. Also verify that fuses #4 and #21 under the hood (PDC) are intact and functioning. If the issue persists, a professional scanner and wiring diagrams should be used—consider checking for a Technical Service Bulletin (TSB) related to U0120/U0121 in 2006 Grand Cherokee models. A qualified technician is typically required for accurate diagnosis and repair.