So I've done some digging and found a little bit of info that I think should be helpful. It would be more helpful if I knew anything about dis-assembly but I am willing to learn.
I found the datasheet for the 167 and have found the addresses for PWM outputs 0-3.
I then searched for those addresses in IDA and came up with the following.
It may be borderline spoon-feeding but am I headed in the right direction? Where should I go next?
Load the binary to correct address (0x800000), convert it to code, then check
references to PW registers.
Won't really make it any clearer, as you'll have to check actual functions working with those. That's a bit too difficult for someone with no (dis)assembly background.