Based on the number of hits returned when one searches for solutions to crippled Kenwood head units, it does not appear to be an uncommon, or isolated occurrence.
I ended up chasing a couple faults with my single-DIN unit, with two issues that were probably consequentially related.
It first started intermittently going into protect mode, saying to "check wiring," suggesting that there was a short in somewhere in the wiring, or at a speaker. The installation was done using soldered and shrink wrapped connections to the factory harness plugs, so I doubted it was in the dash. The speakers, OTOH…?
Another possibility, based on a YT video, was that the board connections to the amplifier IC were corroded. Couldn't find the original removal keys, so I had to order some replacements, and when I was finally able to yank the unit, and remove the rear heat sink to gain access, they looked fine. I cleaned them anyway, and reconnected the unit…
…which resulted in no joy, but a different error message, "Protect Send Service."
Searching for this issue resulted in a plethora of YT hits, and a solution that finally restored functionality. Most, if not all of the videos will suggest removing the unit, and connecting it to bench power of some kind, because it will have to power cycled during the process.
I did not find that to be necessary, as simply turning switched power on/off via the ignition was fine. Save yourself the hassle and try it this way first.
That said, for the record, here is the process to take the unit out of protection mode:
1) With power off, remove faceplate and reset the unit with the recessed reset button. This must be done, or the rest of the process will not give the desired result.
2) Reinstall the faceplate, then turn power on while holding down the 3 and 6 station preset buttons. This should result in the display saying "DC Error." If it doesn't, make certain the buttons are pressed while powering on, and try again.
3) With the display saying "DC Error," press and hold button 1, until the display says "DC 1 0" or "DC 1 OK"
4) Repeat the process with button 2, until the display says "DC 2 0" or "DC 2 OK"
5) Power off the unit.
6) Power on the unit, which should then be functionally normally again.
6a) Enjoy tasty beverage.
In my case, I also found a loose door speaker, and from what I can gather is that it had been intermittently shorting out ("wiring fault"), before reaching the point where one of the leads broke free from the speaker terminal and grounded to the door frame, sending the unit into protection mode full time.
With that corrected, the unit still needs to be taken out of protection mode, which is what the button pressing process does.
These basic concepts should apply to the common chassis shared by many Kenwood and JVC head units, but there may be slight variations in which buttons are pressed to trigger the secret reset sequences.
I ended up chasing a couple faults with my single-DIN unit, with two issues that were probably consequentially related.
It first started intermittently going into protect mode, saying to "check wiring," suggesting that there was a short in somewhere in the wiring, or at a speaker. The installation was done using soldered and shrink wrapped connections to the factory harness plugs, so I doubted it was in the dash. The speakers, OTOH…?
Another possibility, based on a YT video, was that the board connections to the amplifier IC were corroded. Couldn't find the original removal keys, so I had to order some replacements, and when I was finally able to yank the unit, and remove the rear heat sink to gain access, they looked fine. I cleaned them anyway, and reconnected the unit…
…which resulted in no joy, but a different error message, "Protect Send Service."
Searching for this issue resulted in a plethora of YT hits, and a solution that finally restored functionality. Most, if not all of the videos will suggest removing the unit, and connecting it to bench power of some kind, because it will have to power cycled during the process.
I did not find that to be necessary, as simply turning switched power on/off via the ignition was fine. Save yourself the hassle and try it this way first.
That said, for the record, here is the process to take the unit out of protection mode:
1) With power off, remove faceplate and reset the unit with the recessed reset button. This must be done, or the rest of the process will not give the desired result.
2) Reinstall the faceplate, then turn power on while holding down the 3 and 6 station preset buttons. This should result in the display saying "DC Error." If it doesn't, make certain the buttons are pressed while powering on, and try again.
3) With the display saying "DC Error," press and hold button 1, until the display says "DC 1 0" or "DC 1 OK"
4) Repeat the process with button 2, until the display says "DC 2 0" or "DC 2 OK"
5) Power off the unit.
6) Power on the unit, which should then be functionally normally again.
6a) Enjoy tasty beverage.
In my case, I also found a loose door speaker, and from what I can gather is that it had been intermittently shorting out ("wiring fault"), before reaching the point where one of the leads broke free from the speaker terminal and grounded to the door frame, sending the unit into protection mode full time.
With that corrected, the unit still needs to be taken out of protection mode, which is what the button pressing process does.
These basic concepts should apply to the common chassis shared by many Kenwood and JVC head units, but there may be slight variations in which buttons are pressed to trigger the secret reset sequences.
