As title states, I've connected a Pioneer GEX-P5750TVP tv tuner to an AVIC-HD3 headunit using the AV-BUS and IP-BUS cables (IP-BUS goes through a CD-IB100II ipod adaptor). When I select tv on the headunit I get sound, but no picture - just a blank screen. In the manual it says you will get a blank screen if the handbrake is not on. I've tried connecting the green handbrake lockout wires to both the handbrake and directly to earth with no success.

I didn't have an installation manual for the tv tuner and therefore connected up all the wires - including the red power wire. I later found out that the red wire should only be connected if the tv tuner is being used as a stand-alone unit. Could this have done it any damage?

Otherwise, maybe I have dislodged the AV-BUS cable from the headunit while installing it - would this cause the picture to be lost but leave the sound intact?

Any help greatly appreciated.

Does the screen work when the unit is playing without using the tuner? If it works when the unit is playing a cd but once tv is selected then it seems something on the tv tuner isn't properly connected up.

Yes, the screen works for all other functions, including playing video from the inbuilt dvd. Will check the AV-BUS cable tomorrow and make sure it hasn't come loose.