Gear display switch (F208)

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The gear display switch (also known as the gear recognition switch) reports to the DIGISWING controller what gear is currently engaged, or the neutral gate it is in.

Outputs

R 1 2 3 4 5 NG 1-2 NG 3-4

  • NG Stands for neutral gate.

This data is required to prevent an initial start of the car with a gear engaged, and also to turn the engine off when neutral is selected, as well as clutch operation. It is highly likely that the ECU can use this data in the case of absence of the gearbox speed sender to calculate (using the road speed sender) the optimal time to close the clutch as the engine RPM increases to match gearbox speed.

Additional information

When the ignition is turned on the Digiswing control unit immediately checks what gear is selected, if the car is in gear, the clutch is not opened, this is presumably a safety-feature in the event that the vehicle is parked on a slope and is being held by a selected gear, if the clutch was opened, the vehicle may immediately start to roll, this check prevents this from happening, the ECU then relies on a signal from the gear operating switch (someone attempting to change a gear) to operate the clutch to allow them to change gear. On the other hand, if the car is in neutral, the clutch is immediately opened in preparation for an engine start (to reduce load on the starter motor).

It is possible for a fault code to be set for this switch even if it is working correctly, this usually happens if the driver has been "playing" with the gears at a stop, not selecting them properly or only momentarily, causing the gear display control lamp to flash a lot. They may then find all the warning lamps blink as the fault code has been set. This is because the control unit recognizes faults with the sensor based on the plausibility of what it is reporting, one way the control unit detects this is by rapid operation of the switch on and off caused by a loose connection or defective sensor - by playing with the gears they then pass this threshold which would not normally occur under normal operation and thus a fault code is set.