Pedestrian Protection System: Other Jaguar XF I

CONTROL DIAGRAM

Note. A = Hardwired; D = High speed controller area network (CAN) bus; N = Medium speed controller area network (CAN) bus

Failure Mode Detection

In service, if any fault is detected, or any part of the system is recognized as not being present, the message center displays the warning 'Check Pedestrian System'.

The bonnet deployment actuators are non-serviceable components, and if they must be replaced due to a fault, or due to having been deployed, or following any other accident, their barcode labels must be read and recorded in the service database against the vehicle VIN for security purposes.

After deployment of the pedestrian protection system, the vehicle must be stopped as soon as it is safe to do so. The hazard warning lamps will be activated and can only be switched off by pressing the engine START/STOP button to turn the engine off and on again. A warning message 'CHECK PEDESTRIAN SYSTEM' will appear on the message center and the vehicle should be transported to the nearest dealer/authorized repairer. The vehicle must not be driven when the bonnet has been deployed.

Note. If the warning message 'CHECK PEDESTRIAN SYSTEM' appears in the message center when the bonnet has not been deployed, the vehicle should be taken to the nearest dealer/authorized repairer immediately. It can be driven.

If any significant damage occurs to the front bumper it should be inspected by a dealer/authorized repairer as soon as possible.

CONTROL MODULE

The control module is mounted below the hood release lever behind the side trim in the left hand front footwell.

The deployment signal is received from the pedestrian protection system control module. The second-generation system adopted for XF is all-new to Jaguar and, although similar, differs from that introduced on XK by having an accelerometer-based sensing system rather than a contact-sensing system. The accelerometer-based system is supplied by Bosch. Mounted very close to the skin of the bumper, it examines the characteristics of vibration waves caused by impact. Its response time is quicker, because it does not rely on the front of the bumper being loaded. It uses the 'saved' time to make more complex decisions, and so has fewer error states. The speed of vehicle and the length of the bonnet define the time available to get the bonnet into its deployed and stabilized position. It is possible, therefore, to create a time-line counting back from the predicted moment of head impact to the time when the deployment signals need to be sent. That in turn defines a time from first contact to decision time.

HOOD ACTUATORS

The hood actuators are pyrotechnic air bags. The hood actuators are located just forward of the hood latches on either side of the hood. The actuators comprise a pyrotechnic device to raise the hood, a secondary hood latch mechanism and a tether sleeve. Once fired a locking device mounted on top of the actuator couples with the secondary hood latch before the airbag inflates to raise the hood. This ensures that the hood can only deploy to a pre-determined height (approximately 130 mm). As the hood actuator is fired two prongs located in the secondary latch housing are moved out of their retaining clamp. The prongs are spring loaded to grip the secondary hood latch striker securing it to the actuator tether cone. Hood Actuator and Secondary Latch.

They are mounted to brackets in the secondary bulkhead and interface to reinforced areas on the lower surface of the bonnet.

Engine Compartment Lid

The two-piece engine compartment lid is in aluminum and the inner panel has a hexagonal panel structure, which allows energy from a pedestrian head impact to be absorbed effectively across the full area of the bonnet. It also has sufficient strength in the rear cross-beam to accept the forces from the actuators and maintain a stable condition.

When deployed, front bonnet latch acts as the pivot point and the rear hinges allow a controlled degree of upward movement before retaining the bonnet at the end of its deployment, thus limiting its total upward travel and stabilizing its position.

Note. A = Non-deployed hinge; B = Deployed hinge

The hinge system incorporates a number of leaves. This includes a leaf attached to the body, an intermediate leaf and a leaf attached to the hood. During normal operation the hinge opens and closes using the hood and intermediate leaves. These are attached together by a firing pin. When the actuators are fired the firing pins fail. This allows the hood and intermediate leaves to separate and deploy the hood upwards. When the hood deploys the hood latches act as temporary hinges.

Note. The hinges deform during the deployment process and will need to be replaced.

SAFETY INFORMATION

Note. It is advisable not to use a cellular phone or to have a cellular phone in close proximity when working on the pedestrian protection system or components

Note. Given the legal implications of a restraints system failure, harness repairs to pedestrian protection system circuits are not acceptable. Where the text refers to "REPAIR the circuit", this will normally mean the replacement of a harness.

Power Supply Depletion

Before beginning any work on the pedestrian protection system or related components

1. Power Supply Depletion
2. Disconnect the battery leads, ground first.
3. Wait 2 minutes for the power circuit to discharge.

There are comprehensive instructions on the correct procedures for pedestrian protection system repairs in the manual. Refer to the relevant section of the workshop manual.