U0134 indicates a loss of communication between the vehicle's main control module (PCM/ECM) and the rear power steering control module over the CAN bus. This code is typically set when the module does not receive a valid message for a specified time, often due to wiring issues, power/ground faults, or module failure.
Open, short, or corroded wires in the CAN bus circuit between the PCM and the rear steering module are the most common cause. Check for damage, loose pins, or moisture.
Internal failure of the module itself can prevent communication. This is less common than wiring issues but still plausible.
Insufficient voltage or a poor ground connection to the rear steering module can cause it to not respond on the network.
Issues like missing termination resistors, high resistance, or a short in the bus wiring can disrupt communication between modules.
A weak battery or failing alternator can cause intermittent communication loss, especially during startup.
Rare, but a failed main control module can stop sending or receiving messages. This should only be considered after all other causes are ruled out.
It depends. If the rear steering system is inoperative, the vehicle may still be drivable but with reduced stability. Some systems may limit speed or disable other features. It is safest to have it diagnosed and repaired promptly.
No. In most cases, the cause is a wiring or connector issue, or a power/ground problem. Module failure is possible but less common. The PCM itself is rarely at fault.
It is an electronic module that controls the electric power steering assist for the rear wheels, typically found on vehicles with four-wheel steering or active rear steering systems.
Almost never. The PCM is usually the module reporting the loss of communication, not the cause. Focus on the wiring, power supply, and the rear steering module itself before considering PCM replacement.