People...quit guessing....just troubleshoot it.

So, new headunit, and now the subs don't work....unless you really ****ed something up in the installation, the head is the culprit...assuming nothing else in the system has changed....since you didn't say anything, I'm going to guess that there are no other external processors in the chain (line driver, eq, crossover, etc)

Step 1. Put the old head back in and see if it works fine.

If it works ok, you obviously did either a poor job of installing the head (bad ground, RCA's pinched or not plugged in properly, etc) or, the head is broken.

Step 2. IF you can't reinstall the old head, take the rca's from the amp for the highs, and use them to supply source to the subs. Do the subs work? Test your blinker phenomenon?

--if they work fine now, then the problem is before the subwoofer amplifier - subs and sub amp are fine
--if they don't work, you could have caused a problem with both.

It's rare that both heads would prove to be bad, or that the sub amp/install went bad with no changes.

Start with those easy tests, and post results. That will get you on your way to diagnosing the problem....