What is the LIN line voltage?

[JoyAnn]

The LIN line voltage is 12 volts. The control units controlled by the LIN bus are generally distributed in relatively close proximity, and data transmission is carried out via a single wire, with the data line capable of reaching up to 40 meters in length. LIN is a low-cost serial communication network used to implement distributed electronic system control in automobiles. The LIN bus is a serial communication network defined for automotive distributed electronic systems, serving as a complement to other automotive multiplex networks such as the Controller Area Network (CAN). It is suitable for applications where there are no excessive requirements for network bandwidth, performance, or fault tolerance. The LIN bus is based on the SCI UART data format and operates in a single-master controller and multiple-slave device mode, representing a special case of UART.

[DeHarley]

When I work on cars, I often deal with LIN bus lines, whose voltage fluctuates between 0 and 12 volts. Normally, it stays around 12 volts when no data is being transmitted, but when information needs to be sent, it instantly drops to 0 volts before rising again. This change is invisible to the naked eye and requires an oscilloscope to capture the full waveform. If measured with a multimeter, you can only see the average voltage, which typically falls between 8 to 10 volts and is considered normal. The LIN bus is connected to devices like power windows and mirror adjustments—voltage instability can cause them to malfunction. Last time, a car had erratic wiper movement due to excessive LIN bus voltage fluctuations. During inspection, first check if the battery voltage is normal, then examine the LIN wiring for any shorts or damaged insulation.

[Tina]

I've tested the LIN bus voltage on hundreds of vehicles, and its voltage fluctuations are quite fascinating. When idle, the voltage stays at 12 volts, but during data transmission, it rapidly drops to 0.4 volts before bouncing back - this entire sequence completes within milliseconds. Standard multimeters can't keep up with this speed, making their readings unreliable, so an oscilloscope is the best tool for observation. Vehicle secondary functions like climate control and seat heating rely on this communication protocol. Detecting voltage anomalies is straightforward: after starting the vehicle, repeatedly operate a LIN-enabled device while monitoring whether the voltage fluctuates rhythmically. Consistently low static voltage may indicate a short circuit, while a steady 12 volts suggests the module is in sleep mode.

[JeremiahLynn]

I've verified the LIN bus voltage multiple times. After the vehicle is started, the LIN voltage remains stable at battery voltage (~12V) during non-communication periods, but plummets to around 0.35V when communication begins. Repair shops commonly use multimeters - healthy average voltage readings should be between 9-11V. Minor voltage fluctuations during electrical operations like lights or wipers are normal. Clear fault symptoms include: mirrors not folding when locking or window regulators getting stuck. When abnormalities are found, first check fuses, then perform sectional wire testing. I've seen cases where rodent-damaged wiring caused persistent low voltage - replacing the wiring harness fixed it.