What causes the stereo to louse power when put in a gear only.

Not wired wrong. Factory unit,factory wired.Never had any electronic problems with unit or car .100,000.Started yesterday.

Does it loose all power to the radio when in gear or just the speakers drop out. The audio system can give diagnostic codes to help figure out which direction to go with it.

Yes all power.Gear shift acts like an on off switch.

Hope this helps getting a useful code. > Is there any chance that soda or something else spilled in the console or on the shifter if its a console shift? > > Audio Unit Self-Diagnostic Mode The audio unit self-diagnostic mode tests can only be entered while in the speaker walk-around test. The audio unit self-diagnostic mode has five tests available: Preset button 1 = Audio internal/external SELF TEST. This test is an on-demand self-test. If SELF FAIL is displayed, press TUNE > to scroll view the DTCs stored. Refer to the Diagnostic Trouble Code (DTC) Index. If the system is OK, SELF PASS will be displayed. NOTE: Always DOCUMENT, CLEAR and CARRY OUT the CDX6 On-Demand Self-Test again. Preset button 2 = View/Clear continuous DTCs. NO DTCS is displayed if no DTCs are retrieved. If DTCS FOUND is displayed, press TUNE > to view the DTCs retrieved. Refer to the Diagnostic Trouble Code (DTC) Index. To clear all DTCs, press the EJECT button. DTCS CLEAR will be displayed. Preset button 3 = SIGNAL TEST. This test measures the average strength at the current tuner setting. Preset button 4 = Software configuration level. This test queries each audio system controller for its software configuration level. SOFT LEVELS will be displayed upon completion of the query. Press TUNE > to scroll view the software configuration version level. Preset button 5 = DISPLAY TEST. This test will light all the audio unit display segments for five seconds. When the test is complete, DISPLAY TEST is displayed on the bezel. To enter these tests, depress the desired preset button while in the speaker walk-around test or while in the audio unit self-diagnostic mode. To exit the audio unit self-diagnostic mode, turn the ignition switch or the audio unit off. If the concern remains and the fault is not detected, proceed to the Symptom Chart to continue diagnostics.

Speaker Walk-Around Test NOTE: To enter the speaker walk-around test or audio unit self-diagnostic mode, the audio unit must be turned on and in radio tuner mode (AM/FM). The audio unit self-diagnostic mode tests can only be entered while in the speaker walk-around test. To enter the speaker walk-around test, press preset buttons 3 and 6 simultaneously, hold for approximately three seconds and then release. The speaker walk-around test stops at each speaker and applies tone to each speaker for approximately 1-2 seconds. Each speaker is tested and shown on the display in the following sequence: RF, LF, LR, RR, SUBWOOFER I, and SUBWOOFER II. The speaker walk-around test automatically continues and tests Subwoofer I and Subwoofer II for speaker short and audio compact disc/disc jockey. If a speaker short exists, SPKR SHORT will be displayed. If the vehicle is not equipped with audio compact disc/disc jockey or if the audio compact disc/disc jockey is not responding, NO CDDJ or NO DJ will be displayed.

Thanks for all the help.the problem went away last night unit working perfect again.I'll run the test and see what comes up.If has been raining and moisture could be a factor.

Check transmission range sensor, could be bad