Nissan Repair: Infiniti G3 dashboard electrical problem, 2003 infiniti g35, climate control system

Question
QUESTION: Hello,

I know my 2003 Infiniti G35 is not a Nissan but am hoping that you might have an idea re- my problem.  
Just recently, while everything is fine when the car is first driven, after a while, both the air conditioning and radio LED displays go blank and none of their controls on the dashboard work.  The radio and air conditioning continue to work (at their last settings) but none of the settings can be changed.  
Interestingly, all of the radio/CD/tape functions can be changed from the controls on the steering wheel even though you can't see what mode/station you're listening to.  Re- the climate control system, you're stuck with the last setting.
Thanks for any ideas. Mitch

ANSWER: Mitch,

You either have have an issue with the ignition, and ignition relay.  Email me back and let me know if you turn the car off and restart it if the condition goes ways.  Also, does this happen if you hit a bump or does it just do it after a time.  You say when it is first driven it works and then it screws up?  Does the car have an aftermarket alarm on it?  Email me back and we'll go from there.

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

QUESTION: Hello Von,

The first few times this happened, after turning the car off and letting it sit a while, the problem fixed itself.  However now, even when the car is started from cold, the problem exists. The radio and AC displays (even the and LEDs buttons to indicate if the AC is on etc) do not illuminate.  It is obviously getting worse.  The problem started about 2 weeks ago.
Re-hitting a bump, it doesn't seem to have anything to do with it however, 3 years ago we hit a large rock w/the right front wheel that required an alignment.
Re- an alarm, the car has the stock security system.

Thanks again/Mitch

Answer
Mitch,

Ok,  There are a couple of problems here that will have to be addressed.  The body control module is the most probable cause of the problem.  That is, the illumination is a seperate function from the headlights.  The G35 and 350Z have the same basic system. When the car is turned on there is power that is fed to the headunit and airconditioner and as a result it feeds through the computer that grounds a relay.  I would first check the relay for illumination as it also provides power for the unit to change stations and CDs and the airconditioning when on.  If the relay is good then you need to back-trace the ground from the relay and it will probably be the body control module.  This is seperate from the computer that runs the car.  It is located under the dash, drivers side.  If you could get someone with a Consult II scantool it would make the diagnosis much easier.  Otherwise, it is going to be a test light and a lot of taking things off to get access to the harness.