How to install Bluetooth (BT) in the BMW Reverse RDS radio (C52)
⚠️ IMPORTANT: You perform all modifications at your own risk. I am not responsible for any damage or mistakes made during the process.
Items required for an easy & successful installation:
- DIY Bluetooth kit for the BMW Reverse RDS Radio
- Solder, soldering iron, flux, IPA/PCB cleaner, desoldering pump, multimeter etc.
- Torx T8 and T20 screwdrivers
- Flat head screwdriver
- 1,5mm & 3mm drill
- Hot glue
- Scalpel
- Wire strippers & cutting pliers
#. Before disassembly, switch the radio to AM mode for about 10 seconds, press the arrow buttons a few times, and switch back to FM. If the FM station name appears immediately (RDS must be ON) instead of “SEARCH”, continue to the next step. If not, repeat the process.
Some radios don’t recall the last FM station after switching to AM. This procedure usually fixes it. Otherwise, switching between AM and FM may take around 15 seconds to restore the previous FM station (unless you press a preset).
Once the controller is installed, this fix cannot be performed because in AM mode the controller blocks the arrow button signals. In that case, you would need to disconnect the controller to do it.
1. Remove both top and bottom lids using the flat head screwdriver:
2. Remove 2x T20 bolts that are holding the locking clamps and the front panel:
3. Undo these 3 small plastic clips while keeping pressure on the front panel and pushing it slightly forward:
4. Push the front panel forward and wiggle it slightly to loosen the tape deck buttons from the mechanism:
5. Undo 4x T8 bolts holding the tape deck mechanism and disconnect its two connectors simply by pulling them up. Take the mechanism out:
6. Drill carefully 1,5mm hole for the VIN wire:
7. For the microphone input, widen already existing holes with 3mm drill. Use some fitting socket to avoid the drill going in too deep. Use counter clockwise drilling direction when drilling the circuit board. If you also bought preamp outputs with this kit then here is a guide of how to install them.
8. Using a scalpel, carefully scrape off a small amount of insulation and make the 3 cuts exactly as shown in the photo. Do not remove too much material, as the resistor may no longer be able to bridge the gap properly:
9. Turn the radio around and to the same with these two contacts. If they are full of solder use desoldering pump, it makes your life easier later when you have to push through the wires. Also remove the circled SMD capacitor:
10. Add solder to these places:
11. This is the trickiest part where good precision and patience is needed… Add flux and use tweezers/scalpel to hold the 1kΩ SMD resistors in place and solder them over the previously cut and tinned tracks. Make sure they don’t touch with each other (easiest to check against the light) and with multimeter check that there is ~1000Ω resistance between the numbered contacts, if there is 0 or infinity then repeat the task:
12. Pass those 6 wires through and solder them in the same order like is shown on the photo:
13. Shorten and solder the rest of the wires like this:
14. Clean the flux residue everywhere you soldered:
15. Temporarily install the BT module antenna (align the connector and use a flat-head screwdriver to push it in as it requires quite a bit of force) and position the controller so that it doesn’t touch or short out any components. Then reattach the front panel so you can test the radio and BT functions in the car.
If nothing appears on the display, then something went wrong during assembly and you’ll need to look for the issue. Go back to step 11 and carefully double-check all connections — most likely some wires were mixed up:
If the radio turns on normally then go to your smartphone Bluetooth settings, search for available devices and pair with the ”BMW Reverse RDS”. Play some music and increase the Bluetooth volume level from your phone so it would match with the FM level, then there won’t be any noticeable difference when you later switch between these modes:
16. Place the Bluetooth antenna loosely as shown in the photo, making sure it does not interfere with any moving parts of the cassette mechanism. Do NOT stick or attach it to the metal chassis (even though it has adhesive), as this may later cause interference.
Firstly secure the controller and then the wires with hot glue. Avoid leaving them loose or tangled under the cassette mechanism, as they may get caught in moving parts. Route the wires neatly and as low as possible, as shown. Below are also a few examples of incorrect placement:
17. Clean the tone head and reinstall the cassette mechanism. First plug in the tone head connector, then the second one. When fastening the bolts check that its bracket is not sticking over the edge, if it does, push it in while tightening the bolt, otherwise this can later block the metal frame sliding over the radio:
18. Install the front panel. Make sure its connector is going in straight. Push all 3 of the tape deck buttons to lock them in place and also reinstall the 2 clamps and bolts:
If you can hear some interference (knocking sound) when there is no music playing on the Bluetooth mode, adjust the BT module antenna position until it goes away. Secure it in place and reinstall the top lid. WELL DONE! You have earned the chocolate 🙂
