Land Rover Defender: Operation

In a collision, the force of the impact is measured by the impact sensors, pressure sensors and the RCM internal accelerometer. The RCM evaluates the readings to determine the impact point on the vehicle. The RCM also determines if the readings exceed the limits for firing any of the airbags and pretensioner. During a collision, the RCM only fires the airbags and pretensioner if the safing function confirms that an impact limit exceeds.

The RCM incorporates the following impact thresholds to cater for different accident scenarios:

• Front impact, pretensioner.
• Front impact, driver and passenger airbags stage 1, belt unfastened.
• Front impact, driver and passenger airbags stage 1, belt fastened.
• Front impact, passenger airbag stage 2, belt unfastened (NAS market only).
• Front impact, passenger airbag stage 2, belt fastened (NAS market only).
• Rear impact.
• Driver side impact.
• Passenger side impact.

FIRING STRATEGIES

The seatbelt pretensioner is fired when the pretensioner impact limit is exceeded. The RCM only fires the pretensioner when the related seatbelt is fastened.

The driver and passenger airbags are only fired in a frontal impact. When an impact exceeds a stage 1 limit, but is less than the corresponding stage 2 limit, only 1 inflater in each airbag is fired. Stage 2 is still fired, for airbag disposal purposes, after a delay of 100 ms. When an impact exceeds the stage 2 limit, the 2 inflaters in each airbag are fired simultaneously.

On NAS market vehicles, the passenger airbag is disabled unless the front row passenger seat is occupied by a person. On all vehicles except NAS, Australia and Japan market, the passenger airbag can be selected OFF in the IPC . Use the vehicle setup menu in the IPC to enable and disable the passenger airbag.

When a seatbelt buckle switch fails, the RCM assumes the related seatbelt is fastened for the pretensioner firing strategy and unfastened for the driver and passenger airbag firing strategies. When there is a fault with the passenger airbag deactivation switch, the RCM disables the passenger airbag.

On NAS market vehicles, when the side impact limit on the front row passenger side is exceeded, the RCM also evaluates the input from the occupant classification sensor system. In that case the RCM also deploys the side airbag only when the front row passenger seat is occupied by a person.

When multiple impacts occur during an impact event, the RCM responds to the primary impact. Then the RCM sends the appropriate fire signals in response to any further impacts when unfired units are available.

When multiple impacts occur during an impact event, the RCM responds to the primary impact. Then the RCM sends the appropriate fire signals in response to any further impacts when unfired units are available.

Front and Rear Impact Firing Strategy - All markets except NAS market

Front and Rear Impact Firing Strategy - NAS market

IMPACT SIGNAL

When the RCM outputs any of the fire signals it also outputs an impact signal to the BCM/ GWM through FlexRay.

The impact signal is also hardwired to:

• The Powertrain Control Module (PCM)
• Electric Power Inverter Converter Control Module (EPIC) - Plug-in Hybrid Electric Vehicle (PHEV) only
• Battery Energy Control Module (BECM) - PHEV only
• Belt Integrated Starter Generator (BISG) - Mild Hybrid Electric Vehicle (MHEV) only
• All door modules
• Telematics Control Module (TCU) (if equipped).

On receipt of the impact signal, the PCM cuts the power supply to the fuel pump relay and the BCM/ GWM switches into impact mode.

In the impact mode, the BCM/ GWM:

• Activates all of the unlock signals of the vehicle locking system, even when the vehicle is already unlocked.
• Ignores all locking/superlocking inputs until it receives an unlock input, when it returns the locking system to normal operation.
• Activates the interior lamps. The interior lamps remain ON permanently until they are manually switched OFF at the lamp unit. Additionally, the interior lamps return to normal operation after the impact mode is switched OFF.
• Disables the rear window child lock input until the impact mode is switched OFF.
• Activates the hazard warning lamps. The hazard warning lamps remain ON until canceled by the hazard warning switch or the impact mode is switched OFF.

The BCM/ GWM impact mode is switched OFF by a valid locking and unlocking cycle of the locking system.

DIAGNOSTICS

The RCM records any DTCs and related data. The DTCs and related data are read using the JLR approved diagnostic equipment.

The JLR approved diagnostic equipment enables certain components to be activated and also read live data.

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