Abstract: The present document describes a system for offline testing of an installed wiring harness, comprising: at least a first and a second testing module, having: a communication module for receiving test specifications and for sending test measurements; testing equipment for generating the test measurements from the test specifications; each of the first and second testing modules being adapted for connection at a connection point in the wiring harness; a central network management module, having: a communication module for providing the test specifications to the testing modules and for receiving the test measurements; and a test management module for controlling the testing modules.