Complete guide for converting to shark finn on the Astra K:
You have:
13383712 - Original stock antenna without Onstar
You'll need:
13490407 Amplifier for FM/AM
13476638 Shark finn antenna BLACK (GM stock for the Astra K)
and this fakra extension cable:
https://www.ebay.com/itm/Fakra-B-Female-to-Male-RG174-Cable-2m-for-Car-FM-Radio-Antenna-Extension-Cable-/252999609614?hash=item3ae7f3ad0e
Reason is that the versions with an original mounted shark finn antenna has an amplifier in the rear window. It is mounted in the right side of the window.
A fakra extension cable you'll need for connecting the antenna cable located in the sealing. The new shark finn antenna is ONLY for styling purpose. It does not serve any other purpose than this! It can't be connected to the existing antenna cable!
1. Pull down the headliner from the back: fold up the rubber trim at the hatch in top. Then you can pull down the headliner - you'll notice the plastic clip will "pop". Don't worry. It is VERY flexible.
2. Locate the old antenna, use a 10mm socket with a small extender and unscrew the antenna. Be aware - there is plenty of places where you can cut your arm on it the gab above the sealing.
3. When removing the antenna, make sure that you disconnect the cable and the little bracket are rotated correctly to fit the hole in the top. Then you can pop out the antenna from bottom and out from the top.
4. Attach the new antenna using the reverse method - make sure that the sealing between antenna and the roof are tight, but not too tight as water will enter here and damage you sealing/electrics.
5. Remove the plastic trims in the rear window. It is only plastic, and it makes a lot of noise when you are removing them.
6. Locate the bolt for the antenna extender in right top of the hatch.
7. Unscrew the bolt and mount the amplifier for the FM/AM.
8. Here you'll need to mount the "little" antenna for the rear window with some double sided tape on the spot for the antenna in the window glass (I recommend 3M as it is tolerates cold temperatures).
9. Wire the fakra extender cable through the left hand sided (or right hand side - depends on UK or Europe version :lol: ) through the rubber wiring protection (see the photo and notice this has both rubber wiring protection. Notice: it is very TIGHT here! You might need a solid tube to force the cable through. You might break the cable here, since the head of the fakra cable are not easy to pull through this rubber protection. Try it out yourself.
10. Connect the existing antenna cable from the roof with the fakra extender cable, and the connect the amplifier with the fakra cable.
11. Put back the plastic trim for the rear window and put the sealing back, and remember to place the little rubber trim correct for the edge of the sealing.
I hope that you enjoy my guide..
By the way - antenna signal improves A LOT using the amplifier.