Introduction: VW AG 9w3 Bluetooth Module Repair
The Bluetooth function in our Skoda superb MK2 doesn't work, checking using vagcom showed that the device is coded but not responding, the solution on the forums is to unplug then plug, and if that doesn't work, buy a new one which is very expensive.this got me wondering why is this common on these modules ?! so, an exploratory surgery was a must .
Step 1: Disassembly
The module is located below the passenger seat beneath a plastic cover.
- The cover is removed by sliding it forward.
- The connector is unplugged by pressing the small black tab gently and sliding the white lock away from the wires.
- The module is held by a metal plate , which is bolted using three screws, just loosen the two in the back and remove the one in the front using 10mm socket or torx t-30, then slide the module out.
- The antenna is removed by pinching the yellow plug and sliding out.
- The unit is held together by only four t-10 screws
Step 2: The Fix
Upon inspecting the board i immediately noticed the huge black blob around the first pin of the connector and on the cover, this stuff obliterated the pin and oxidized the copper. the board was also damaged on the other side as well, at first i thought that this is a bad short circuit which the fuses missed, but this is clearly something chemical.
The enclosure had no sign of this substance on the outside, so i assume this is from the factory.
i tried cleaning it with rubbing alcohol and a brush but this stuff wouldn't budge, so i used a rotary tool with a brass brush attachment at the lowest speed.
The damage was to the first pin, which is the +12 volt pin (Power supply) which -thankfully- is easy to track across the pcb. also to a multi-layer via on it's left with no sign of copper left in it.
The 12 volt rail was inspected for shorts and bad components, but everything is high quality and in top shape.
The pin is connected to the via through one of the layers in the middle.
- A tinned wire is inserted to the via and soldered on the capacitor on top and on the pad on the bottom.
- another tinned wire is soldered from the pin to the pad next to the via on the bottom.
Step 3: Assembly
The enclosure is designed to surround the connector pins, which when assembled will press on the soldered wire and cause a short circuit directly to ground.
- Paint is applied on the soldered wire and then the board is put on the enclosure to determine where the wire and the enclosure meet.
- The enclosure then is ground away using a rotary tool with a cutoff disk and a drum sander bit .
- The wire and the newly made notch are covered with paint to prevent arcing, though unlikely.
after the paint dries the unit is assembled and put back, the unit should be recognized immediately without having to remove the battery or use Vag-Com, though in my case the MFD doesn't display the contacts and needs Vag-Com cable to fix