Seat Belt Tensioner

Seat-belt Tensioner Diagrams:

Seat-belt Tensioner Components:

Locations of components

3 Earthing point, facia
At the left-hand front speaker socket

20 Ignition switch
On the right-hand side of the steering Column

235 Seat-belt tensioner left-hand
At the extreme bottom of the left-hand rear door pillar

236 Seat-belt tensioner, right-hand
At the extreme bottom of the right-hand rear door pillar

237 Test tapping for seat-belt tensioner
Under the driver's seat

238 Electronic control unit for the seat-belt tensioners
In the front part of the centre console

Operation
The seat-belt tensioners are fitted to cars for the following markets:
1987: USA
1988: All

The seat-belt tensioners are designed to tension the two front seat belts if the car should be subjected to a high rate of retardation, roughly corresponding to a head-on barrier collision from a speed of at least 18 km/h. The speed necessary to activate the belt tensioners is higher if the collision is diagonally from the front. The belt tensioners will not be actuated in the event of a collision from the rear or from the side, or if the car should turn over.

The system is controlled by an control unit which includes a sensor that will initiate a signal if a certain "g" value is exceeded.

Control unit 238 is energized when the ignition switch is in the drive position.

If the car is subjected to a high retardation rate, the control unit will deliver a current pulse to seat-belt tensioner 235 (left-hand side) and 236 (right-hand side). The current pulse fires an explosive gas mixture in the belt tensioners, so that any slack in the seat belts will be taken up.


NOTE:
Test tapping 237 is intended for inspection during production and must not be used for service fault- tracing.

Fault-tracing hints
Check the seat-belt tensioners with the ignition switch in the drive position. Note that the connectors at the two tensioners must be removed before fault-tracing is started. Never measure at the terminal pins of the seat-belt tensioners.

1. Check that the circuit up to pin 5 of the control unit is live.

2. Check the wiring and earth connection.