Particularly those strong in the car audio category.

I recently got a 1999 A4 1.8TQM. anyway the previous owner had hooked up a aftermarket head unit. looked very professionally done. So i had to get emmisions tested and the OBD port would not respond. After much fiddling i removed the radio and the port was responsive again but hen i hooked the radio up it once again became non-responsive. The radio is a Sony CDX- m9900 the wiring is fairly simple just ignition, and battery wires running to the corresponding inputs and the speakers and the ground grounded to some metal behind the radio. Not expecting too much out of this but i figured id ask.

And hi to everyone on the forums. Will post some pics of my car after i remove the disgusting front bumper and fiberglass hood the previous owner had put on[:@]. makes me want to lose my lunch.

 

Thats strange about the OBD Port. You should rig some sort of kill switch for the radio when you need to use your OBD port. Welcome to the forums.
Love your screen name btw!

 

let me get this straight.. he ran the power wire from the ignition.. not sure if I follow.. i would change that if thats the way he ran it.. that kill switch is a great idea.. other then that i would just try re-running the constant power and rerunning the intermitant power and the ground..

 

thanks i thought it was creative. i guess that is the best way to do it i have had an electrical nightmare so far. Dont get me started on the snafu of wiring my amplifier(I still havent finished)[X(] and the real problem is i have a misfire on cylinder 2 also so im guessing coil pack or spark plug needs replacing. I SEARCHED and already know how to check the coil packs please keep the newbie flaming to a minimum altho for the hell of it have a little initiation fun at my expense!

 

there was already an aftermarket radio in there so i ran the power wire from the radio to the one that was giving a steady 12v and i ran the ignition wire to the one that juiced 12v when i turned it on. Hopefully that clarifies a bit. But yeah i am gonna have to take it apart and rewire everything. Hopefully it works because i love the way the head unit looks and it was kinda pricey!

 

thats very odd.. what year is your car?

 

1999 pre facelift.

 

interesting.. i have the same car, and i have an aftermarket radio.. but i have no problem.. interesting.. check all the wires that lead to your OBD port make sure non one then have been messed with.. i wounder if when he took the stock radio out his radio locked up and asked for a code.. maybe that could have messed something up.. i dought it but anything is posible these cars have some odd electrical problems sometimes..

 

Use the search!! Just cuz you're newer than me...