Redundant Data Storage: Notes

In the event of a new instrument pack having to be installed, certain information needs to be maintained to prevent data loss. This information is transferred continuously from the instrument pack on the I bus and is received and held in an EEPROM in the LCM. The data is also stored, along with other vehicle specification data, in the immobilization ECU.

The data stored is as follows:

Vehicle Identification Number (VIN)
Total distance travelled
Service interval fuel volume and type of last service
Service interval clock.

When a new instrument pack is installed, the LCM will update the instrument pack EEPROM with the stored data providing the following parameters are met:

The VIN in the instrument pack and the LCM match
The total distance reading in the instrument pack EEPROM is less than 158 miles (255 km)
The total distance reading in the LCM EEPROM is less than 999,900 miles or kilometers or equal to or greater than 0 miles or kilometers
The total distance recorded in the instrument pack EEPROM is less than the distance travelled stored in the LCM EEPROM.

Vehicle coding data, such as engine type, market, etc., is stored in the immobilization ECU and retrieved by T4 and used to update the new instrument pack.

If the VIN in the instrument pack is set to 0, only service interval data is passed from the LCM EEPROM to the instrument pack RAM, it is not stored in the instrument pack EEPROM. The total distance displayed in the odometer LCD is frozen at the value stored in the instrument pack EEPROM.

If any of the stored data in the LCM EEPROM conflicts with the data within the instrument pack, a lamp, known as a manipulation point, is illuminated in the pack. The manipulation point is located in the trip meter LCD, below the 'Miles' text or next to the 'km' text.

The following conflicts will illuminate the manipulation point:

The VIN transferred from the LCM on the I Bus to instrument pack is 0
The VIN in the instrument pack is 0
The VIN in the LCM is different to the VIN in the instrument pack
A default value in the EEPROM is used until a CAN index message is sent when the ignition is switched on.

If the EEPROM is in an unlocked (unprotected) condition, the manipulation point will flash, irrespective of whether or not the stored data matches or conflicts.

CAUTION: When a new instrument pack is to be installed, T4 must be connected to vehicle and the instrument pack renewal procedure followed to replace the pack. This will ensure that vehicle coding data is correctly installed in the new instrument pack. T4 will also record the current service interval data and restore the settings to the new instrument pack.

Fig 1: Identifying Connector C0230, C0233 And C0234 Terminals

Courtesy of LAND ROVER NORTH AMERICA, INC.