I've got a Pioneer AVH-P4300dvd on the way. Just recieved my Metra JBL-compatible wiring harness for my 2003 Sequoia. Looking at the Metra wiring harness, there's no dimmer wire. Now I've read this is a common problem with this particular harness, but what's the fix? Can I just tap the factory harness dimmer wire and connect it to the Pioneer dimmer wire? If so, which wire is it on the factory wire loom? Thanks for any help you can provide.