Updated: 30-Jun-2025
Factory-installed Radio Info
Factory radios (part numbers & M-codes): 
Factory radio controls (North America):
SAFE mode security code instructions:
Radio Wiring
What size radio will fit? Any single-DIN radio will fit; the only size restriction will be the depth and that is usually a result of a bracket at the back of the radio. Search for radios at BestBuy.com and/or SonicElectronix.com and/or Crutchfield.com; they will narrow down choices based on your vehicle using their "fit guides".
Modern head units have an accessory-on (ACC) wire, something the Cabriolets do not have. Not connecting the ACC wire can result in the car's battery being drained whenever the unit is not in use. How, then, is the ACC wire connected? Download the guide below for instructions.
Radio wiring guide:
Heidelberg radio replacement connectors: VDO Cable Kit CA0504U-LS
Heidelberg-to-Aftermarket radio harness: Scosche VW01B
The AKTIV System
An amplified stereo system installed on '91-'93 USA Cabriolets and Euro Cabriolets with Gamma radios. Read all about it by tapping here.
Speakers
Factory speaker sizes
- 1980-1981
- Front: 4x6"
- Rear: none
- 1982-1990
- Front: 4x6"
- Rear: 3½"
- 1991-1993
- Front: 5¼" with 1" tweeters
- Rear: 4x6"
Accessing the rear speakers
Pry off the cover of the window crank and rotate it out of the way, remove the screw and pull the handle and washer off. Then, gently pry the panel off using interior trim removal tools (use your fingers to feel where the clips are; center the tool around each clip).
Upgrading the speakers
Depending on the dimensions and mounting hole locations, some aftermarket replacement speakers fit no problem, while others may take a bit of modifying. Those with pre-1991 Cabriolets can install the speaker grilles, front speakers and door pockets from a 1991+ Cabriolet (but may need to enlarge the speaker hole, depending on speaker magnet size). And of course the speakers can be upgraded to more modern, better sound-producing speakers; most online car audio retailers (listed in the side bar) have compatibility searches. Will you need to install an amp? That's entirely up to you and depends on what type of system you're installing. Installing what are essentially stock replacement speakers do not require an amp, even if you're running new 100w speakers off of the original 45w head unit.
1982-1990 owners: Wanting to upgrade to 4x6 rear speakers? The factory-original speakers from a 1991-1993 Cabriolet will bolt right in (if wanting to use the rear panels and/or speaker grilles, you will also need the extended window crank assemblies... details below). Aftermarket speakers will depend on mounting holes, depth, etc.
Extended window crank assembly parts and part numbers:- Spline/spacer adapter (155847363)
- Gasket (411837447)
- Base (155837595)
- 18mm screw (N0142675)
- Washer (N0121301)
- Crank (321837581, without chrome; 321837581A with chrome)
Replacing the Antenna
You must remove the driver's side wheelhouse liner to gain access to the antenna housing and cable inside the fender to replace the antenna.