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234 ELECTRIC/ELECTRONIC SYSTEM D AILY Base - May 2004 The pretensioner is an explosive device activated electrically with a signal leading from the electronic control unit; it is an integral part of the seat belt reel and forms a single component with it which is fastened to the vehicle pillar. It comes into action in the event of a crash of a certain entity, in order to take up the unavoidable slack in the seat belts due to the action of the weight of the body, keeping the body close to the seat back. device has been triggered. vehicle takes place, the electronic sensor in the control unit sends a signal which ignites the explosive charge (ref. A) of the gas generator (detonator). pressure of which generates a force that pushes the rack and pinion piston (ref. C) upwards. (ref. D) which reverse the direction of rotation of the belt rewinding it a few centimetres. - The charge for the driver's pretensioner is connected to the control unit on pins 1/2. - The charge for the passenger's pretensioner is connected to the control unit on pins 3/4. - The charge for the centre pretensioner is connected to the control unit on pins 16/17. REEL WITH PRETENSIONER TECHNICAL VIEW OF REEL WITH PRETENSIONER BEFORE DEPLOYMENT A. Explosive charge - B. Propellant - C. Rack and pinion piston - D. Gears TECHNICAL VIEW OF REEL WITH PRETENSIONER AFTER DEPLOYMENT A B C D The belt is unserviceable after every crash and needs to be changed. NOTE Figure 276 Figure 277 Figure 278 |