Code U0135 indicates that the vehicle's main control module has lost communication with the Front Differential Control Module. This means the network signals required to manage the front differential are missing or corrupted.
Corroded, frayed, or broken wires in the communication network connecting to the front differential module.
A blown fuse or failed relay preventing the front differential control module from receiving power.
Internal electrical failure within the Front Differential Control Module itself.
Corroded or loose ground connections causing the module to shut down or lose signal integrity.
A failure in the main engine computer's ability to process signals from the differential network.
No, U0135 is a communication code. It indicates an electrical or electronic failure, not necessarily a mechanical failure of the gears or axles.
No. Communication losses with peripheral modules are almost always caused by wiring, power supply, or the peripheral module itself; replacing the PCM is rarely the correct fix.
The vehicle is generally drivable, but the AWD or 4WD system will likely be disabled, which can be dangerous in slippery or snowy conditions.