During the winter, I have been refurbishing my e30 325i. I have just completed the task, however I had to disengage a significant portion of the wiring inside and around the passenger footwell in order to address a little amount of corrosion. I reconnected the wires, resulting in the malfunctioning of the rev counter and onboard computer. The computer unit's monitor illuminates, but, no numerical values are shown. I have seen a little yellow wire with a connector dangling from the rear of the device. Is there any connection to this? I have successfully disengaged and reestablished all the electrical connections in order to verify that no errors have been overlooked. Any anyone who can provide light on this matter will be highly regarded. Thank you.