Most automotive stereo shops have the wire harness for the Caliber. It's less than $20 or so and makes things easy without having to cut and splice your cars wires. Still have to run a seperate keyed power lead. Easiest is to run a short lead to the 12volt power plug outlet.
The ones in the parts store WILL NOT
work, at least not for making an extension cable to put between the car harness and an REC. The connector coming off the car has 18 leads hooked up. The adapters at the parts stores only has 16 leads coming out. Any good audio shop should have a premium-type harness, $60 around here, that will work. Ouch. Around here in CA, Fry's Electronics, whom I don't care for to begin with, is where I found the expensive, working, 18 lead connector.
I found out the hard way on this topic. Purchased an aftermarket HU harness, a reverse harness (the one coming off the car into the factory HU), and tried to connect them together (making a harness extension if you will) so I could cut/splice/add stuff to the extension rather than the factory wiring.
Long story shor... erm, long, after connecting the new harnesses together, hooking the newly made extension to the car, wiring up the amp via high-low converter, mounting the sub, putting the dash back together, and using a few harsh words, I had to take the radio bezel out again and just tap into the factory wiring (like I didn't want to do).
Hope that makes sense, currently sick as can be and piratically replaced all my fluids with meds! Hope its not the Swine Flu! haha...