Expert: Ernesto R - 1/20/2011

Question
QUESTION: Hi Ernesto. I currently had a Pioneer DVD/Nav unit installed in my pickup. The first thing I noticed after picking the vehicle up from the installer is that I could not dim the illumination on the new head unit (pioneer AVHP3200BT). The second thing I noticed is that the unit would not allow me to play DVD's because it had no park brake input. I took the truck back to have these issues rectified, but the installer is telling me that there is no illumination wire on the OEM side for the radio. He also said that he couldn't get the park brake input to work and simply wired in a toggle switch instead.  
My question is this, does the 06 GMC have an actual illumination wire and if not how did the OEM radio dim if it didn't. Any help would be greatly appreciated.
Thanks:
Steve

ANSWER: ohh yes there are 2 wires for illumination on the factory harness, he just need to test them with a volt meter, there is a constant on off and one that will go from 0 volts to 12 volts using the control on the lights switch

also there is a way to use the parking break switch  they  need to use a relay because the pioneer works on ground and your brake is positive

good luck


---------- FOLLOW-UP ----------

QUESTION: Thanks Ernesto.
Do you know where I might be able to obtain a accurate wiring diagram for my truck?

Answer
when they did the radio installation they add a harness or vehicle interface to keep the warnings working  the harness looks like this unit

http://www.oemautosound.com/pc-218-132-pac-c2r-gm24.aspx


you need to use one of the 2 oranage wires, test them with a volt meter no test lights or it will damage the circuit

good luck