Abstract: The object of the invention is to provide a water immersion detecting circuit, which is free from false detection and is stable and highly sensitive in operation. There is provide a water immersion detecting circuit provided on a printed board 11 of an electronic unit and used for detecting water immersion of the electronic unit based on a change of resistance generated between a pair of sensor electrodes for detecting water immersion P10, p11, wherein the pair of sensor electrodes P10, P11 are positioned opposite to each other on the printed board 11, and a U-shaped slit (opening) 12 is formed between the sensor electrodes P10, P11.

Abstract: A communication network for vehicle control and a method of diagnosing the same in which the self-diagnosis functions attributed to some of control units in the communication network are combined with a manual diagnosis operation, whereby the diagnosis can be carried out by a relatively simple arrangement without sacrificing readiness and correctness, thus ensuring higher cost performance and reliability. The communication network includes control units, each coupled to at least one of auxiliary input and output devices, connected with communication lines to one another for transmitting and receiving unique signals. Each of at least two of the control units includes a transmitter, a receiver, a controller, and an indicating means, and has a diagnosis function.