Hi folks,

I'm new to this forum but have been around others and am fairly familiar with vehicles in general. I'm 64 years old and live in Oklahoma.

I have a 2000 Audi A4 1.8L turbo Quattro, manual 5 spd. transmission.

For quite some time the back-up light have not worked and I decided to investigate finally. Found the F31 fuse blown. Changed the fuse and immediately on turning the switch on it blows again. I pulled the connector off of the back-up light switch. Fuse still blows. My Haynes Manual shows the fuse also provides power to the Mass Air Flow Sensor so I pulled that connector as well. Fuse still blows immediately when switch is turned on. Multimeter checks show a short to ground on the output side of the fuse so to me it appears I have a wiring problem. My Manual is not as comprehensive as I would wish to further troubleshoot so I;m looking for alternatives or a wiring manual source that shows a complete system to further isolate.

I do get a check engine light and it indicates secondary air pump low flow (code 144). Car runs fine and all other options work.

Thank you all in advance for redirection or info.

Whitey Cook