Andrew
If you did nothing to reconfigure the fiber optics, I'd also caution you to recheck your work because the 170 chassis, when adding just a CD changer, will almost always need some reconfiguration work.
To do a quick check of the system:
Partially remove the radio
remove the fiber optics wire JUST from the cd changer, and have a helper turn the radio on while you watch the fiber optics in the trunk.
When the radio is turned on you should see one side (I believe the red side) blink 3 times.
If this is OK, reconnect the fiber optics to the changer again and shut off the radio.
Remove the fiber optics from the radio.
Turn the radio on, and watch the fiber connector that was connected to the radio.
One of the fiber optics lines will now also blink 3 times, the light source is from the changer itself.
On the one in the trunk, the light source is from the radio. The system is attempting to establish ring lock, but can't because in both cases a connector is removed. It tries 3 times, then gives up.
If one of these isn't correct, you should fix this problem before having the radio programmed.

Gilly