The red LED will just flash when the battery in the fob is low if that's the setting in the BCU. If the LED stays on solid means the vehicle is immobilised and if you can override that with an unlock command the problem is with the passive immobiliser which should be disabled when you turn ignition on. If this happens with both fobs and they are D2 fobs not Rover 75 ones(which are the same from outside) then the problem is with the passive remobilisation exciter coil which doesnt react to the fob but unlocking with fob remobilises the vehicle for 30 seconds
Passive coil
The passive coil is located around the ignition key barrel. When the BCU detects that the ignition key has been turned
to the crank position, the vehicle's immobilisation system is activated and a signal is sent to the passive coil at a
frequency of 125 kHz. The magnetic field generated in the coil is induced in the remote transmitter to trigger a remobilisation
signal
.... The BCU controls the passive remobilisation exciter coil (located around the ignition barrel) to generate a magneticfield which causes the handset to transmit a remobilisation signal. The BCU receives the signal and allows the vehicle
to be started. If a valid signal from the handset is not received within one minute of the ignition being switched to
position II, the BCU stops the passive coil from generating the magnetic field.
Discovery Td5 (2000), manual, tuned
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