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The code P0650-04 is for the check engine light not lighting up when the ignition is turned on.
The circuit for the lamp has a 12v supply to the instrument panel at pin 3. Then it is earthed through pin1. The earthing is done by the ECU (pin 49). The wire (brown/white) goes via pin 30 on the 102 pin connector under the left hand windscreen pillar, and pin 17 on the 24 pin connector in front of the battery and a black/white wire to the ECU.
On the diesel the pins on the ECU are very vulnerable to corrosion. The ECU is in the front wheel arch under the right hand headlamp. There's a lot of water spraying around that area, especially if any of the panels are loose or cracked.
