This problem could appear on 2 specific cases:
- The car has DSP
- The CD changer plug has been connected in a wrong way on the cable of the GWL3BM1 (17 round PIN connector)
DSP: If the car has DSP, the Gateway is officially not compatible, due to limitations of the Gateway device. DSP systems require a digital input but the Gateway provides analogue so in those cases there will be no sound, only control. Having a DSP option is rare, there is no label on the radio. You can tell if you check the Tuner. If you see a coax connector, then it must be a DSP based system, but a service station can also help you to find out if the car has DSP or not.
Alternatively: If the car has DSP, and you still prefer to install the Gateway, then you can use a DSP analog-digital adapter (for example Blitzsafe).
CD changer plug: The small 10 pin CD changer plug is a separate cable that you can find on the 17 round PIN plug. This 10 pin plug can accidently be connected in 2 ways to the head unit’s CD changer port. If the radio sees the Gateway but there is no sound, it could be sign of improper installation. Please rotate the 10 pin plug by 180° and plug it back in.