VEHICLE IDENTIFICATION
| Application | Engine |
|---|---|
| 1999-2002 Discovery II | 4.0L |
| 2003-2004 Discovery | 4.6L |
VEHICLE IDENTIFICATION
OPERATION
For IDM inputs which are also inputs for BCU functions, the delay before the BCU recognizes the change in input status is less than 250 ms. The BCU uses a debounce algorithm to ignore changes in input having a duration less than 100 ms with the exception of automatic gearbox W, X, Y, Z inputs, which have a debounce period of 33 ms.
Reverse Gear - Rear Wiper Operation
The BCU changes the operation of the rear wiper when the front wiper is active and reverse gear is selected. The rear wiper operation rate used when the preconditions have been satisfied depend on the prevailing front wiper operating mode and the position of the rear wiper switch. If the rear wiper is on or the front wiper is operating at an intermittent rate when reverse gear is selected, the BCU will operate the rear wiper continuously for 4 seconds via the IDM. After the initial period, the rear wiper will operate at the same rate as the front wiper.
The BCU checks for the following inputs to determine when to provide the rear wiper enable signal if the vehicle is in reverse gear
- Ignition state.
- Rear wiper switch.
- Front intermittent wiper rate.
- Reverse gear selected.
- Front intermittent wiper switch.
- Front wiper switch state.
- Front wash/wipe in progress flag.
In the event of a communications link failure occurring while the reversing wipe is in operation, the rear wiper enable output is switched off.
Head Lamp - Washer Operation
The headlamp wash will only operate when the headlamps are on, and then only every third time the front windscreen wash button is pressed. When the BCU operates the headlamp washers, it activates the washer pump relay for a period of 500 ms. The BCU supplies an earth path for the coil of the power wash relay located in the engine compartment fuse box when the washer function is selected.
The BCU checks for the following inputs to determine when to provide power to the headlamp power wash relay
- Ignition state.
- Front washer pump switch.
- Dipped beam.
- Main beam state.
If the ignition switch is in the off position, the headlamp power wash relay is also held off. if the ignition state is crank, the headlamp power wash relay is switched off and the headlamp power wash counter is reset to Zero.
In the event of a communications link failure occurring while the headlamp power wash relay in on, the relay remains on until the 500 ms timer has completed, then the relay is switched off.