Warning:  This is going to be a long post. 

 

I bought the x920bt in March 2011, originally installed in my F-150 with no issues.  Attempted the bypass at the same time and it worked for about 30 minutes.  I was able to input nav data while driving, play a dvd etc.  At some point in my test run it mysteriously crapped out.  I spent hours and days troubleshooting, checking grounds, reconnecting mute to parking brake, pulling the mute wire back out and swapping the pins.  All to no avail.  Eventually I gave up and just clicked "OK" on the stupid "System has detected improper installation of parking brake cable" every single time for 2 years

 

This persisted until last week when I bought a 2010 FJ Cruiser.

 

I thought to myself- "Self, you are going to do it right this time".  So I ordered a new x920bt A/V harness and power harness along with all the other components necessary for my install.  Got everything hooked up, mute wire is transferred one pin over, connected to parking brake wire, parking brake wire grounded (confirmed in menus of head unit) and it's still not working.  Spent lots more hours troubleshooting and double checking my mute pin, connection to parking brake cable, parking brake cable to ground etc.  Still doesn't work.

 

At this point, there wasn't much left for me to troubleshoot.  So I decided to hold the wire direct to the pin that correlates with the bypassed mute wire.  I believe it's the bottom pin one over from the left as viewed from the rear of the head unit.  Fired it up and watched the screen, and the stupid message pops up.  I read on here somewhere that it'll give you the message on the first cycle after it is bypassed, so I shut it down and turned it on again.  Still has the message.  Examination of the pin reveals it appears slightly different than the others.  It is a hair darker as if it were burnt.  I pushed and pulled to make sure it is tight and it is.

 

The only possible explanation I can think of is that when the bypass originally failed 2 years ago, it was internal to the pioneer unit.  At this point I don't know what else to do.  Surely my unit is out of warranty.  I am going to explore the potential of using a tablet as a head unit.