Receiver Loses All Settings After Ignition Turned Off

[Oka]

Electrical Issue. I have a very unique situation, have Googled but can’t find an answer. To date, I have installed six car stereos. Got a Kenwood DPX502BT CD receiver for a 2006 Toyota Sienna. Installed it with a steering wheel control adapter (Crux SWRTY-61S Wiring Interface). Below are the incidences so far.

1. Receiver never keeps any settings after the ignition if turned off and turned on; usually wait about five seconds after turning off.
2. Got a replacement unit (same make and model), this time, the settings stayed on for four days then lost just the date and time settings.
3. Completed the settings again, then lost every settings after the third turn off of the ignition.
4. Repeated all the settings again and they have kept on since the past three days now.
5. Just curious, removed the second receiver and plugged in the first one that had the most issues, all settings stayed on after three ignition turn-offs.
6. Waiting for the unit to keep on losing all settings so I can have a yellow fused line connected directly to the battery,

How could two units do the same thing with a ‘good and healthy’ new battery? The info I found are where the yellow and red wires were connected wrongly. I called Kenwood but they find such situation very unique with not answer. Kenwood asked me to take it to a professional – this I refuse. I did a good work, especially this installation is even simpler with all main connections through the harnesses.
- All settings are lost every time, after the ignition is turned off.
- Battery is two months old.
- Voltage is correct.
- Dash lights are all nice and bright, no dimming with fan/heater on.
- Voltage checked at end of van’s harness.
- Voltage checked at end of receiver harness, all are good.
- Yellow (constant power) line connected correctly from van’s harness, through the steering adapter to the receiver.

Thanks.

[reverend]

Use a voltmeter to make sure the constant power actually HAS constant power. Your radio is expecting it on the input and it acts like it's not getting it.

[Oka]

'revernd' that's what I mentioned here from the result of a voltmeter:

" - Voltage checked at end of van’s harness. "
" - Voltage checked at end of receiver harness, all are good. "