You said that the antenna works fine in another car. If your dash switch is in the MAX up position, and your antenna still does not rise all the way, then most likely your dash switch is at fault.

Do this....disconnect the plug from the top of the antenna. Make sure dash switch is in MAX up position. Put the ignition on to turn on the radio...make sure the radio is now on. Now, check pin 1, 5, and 4 for power. You can use a meter or probe. I use one of those cheap probes with the built in light and nice alligator clip for the ground. Mine lit up nice and bright.

If any of these do not light up, you have narrowed down your problem.