Yea, that doesn't make sense
Yea, that doesn't make sense
I know I'm chiming in a bit late on this, but I'm experiencing the exact same issue with my JVC KW-R500. As with the OP, I'm positive that the RCA's are connected to the rear/sub output. I turn on the high pass filter and my subs stop working (well, they stop putting out sound). I was "relieved" to see someone else with a JVC HU is having the problem. That means I'm not going nuts.
Anyhow, if the OP sees this, I'm curious as to how your situation turned out?
Obviously JVC is having this issue on more than one model. Not good. I'll be replacing this mediocre HU relatively soonish for a different brand but I'm curious about what JVC told you if you contacted them. (My HU also seems to have weak RCA voltage, but that's a whole other topic.)
I'm your neighbor down in Tucson. I have the exact same issue with my JVC KD-R730BT and your thread was the first thing that came up in a Google search. My unit will not pass (or pass very little) sound to the subwoofer while the HPF is turned on. My unit actually has completely separate sub out jacks on it. After emailing back and forth with JVC trying to get past their canned responses, they told me earlier today that a firmware update would resolve the issue. And of course you have to have an "authorized technician" do the update. So it looks like I am driving across town for a firmware update next week.
So you might want to email them about your head unit. Could be it also has an update to resolve the issue. But it is definitely malfunctioning.
JVC KDR-530 does the exact same thing. I switched to a Kenwood and the HPF is 100 times better :)
Similarly my JVC R800BT HU will not operate my mono amp when in SubWoofer mode. It has front and rear pre-outs and I'm using the rears. When it's set to "rear" rather than SubWoofer it works fine with plenty of bass.
So this of course renders the HPF un-usable since it only works in Subwoofer mode. That kind of ***** since I would like to cut some of the bass from the head unit to the front & rear speakers since they're not very good at handling bass (nor do they need to be), which distorts the mids & highs at higher volumes.
It appears that there is some kind of flaw in the system when these units are used for subwoofer outputs and utilizing the HPF.
In mine it appears that the output level to the mono amp is much to low to provide a decent signal in this mode, although I haven't actually measured it.
Ok I had the same problem, contacted JVC, was told there is an update to fix this issue. updated the firmware and now it is working as intended. here is the info you will need to do this yourself. As always when dealing with firmware updates, it is critical to pick your model # and update it as instructed. The update doesn't state it will fix the HPF/No sub issue but, I can assure you it does.
Website for update and instructions:
JVC Mobile Entertainment Car Navigation Updates
Hope this helps.