Crash Sensor and Standby Power Unit, Replacement
CRASH SENSOR AND STANDBY POWER UNIT, REPLACEMENTNote: The crash sensor has an 8-digit identification number which must always be quoted when ordering new parts.
Crash sensor
The ground connection on the crash sensor used on models from 1989 on is of a new design which is bolted directly to the mounting bracket. Only the new type of sensor is available as a spare. Since the ground connection is made through the mounting bracket, it is very important that this be attached securely to the body.
The sensor is sold only in kits supplied complete with bracket, lock washers and new bolts.
(Although these kits are also used on 700s from 1989 on, the existing bolts are reused, without lock washers. Thus, the bolts and washers in the kit should not be used in this instance.)
Switch off ignition
Disconnect battery ground lead.
Unbolt driver's seat and tilt backwards
Remove bolts securing slide rails to floor. Open seat wiring connectors. Tilt seat backwards. Lift carpet and remove heating duct.
Remove soundproofing panel under steering wheel
Open connectors at centre console and connectors for seat belt tensioners
Caution!
Never disconnect the crash sensor connector. This is extremely important to maintain maximum reliability of contact.
Never separate the sensor from the mounting bracket.
1987-88: Cut away plastic tape under mounting bracket
Use knife to cut tape around bracket (pressing lightly to avoid damaging paintwork).
Remove crash sensor and standby power unit
Disconnect standby power unit connector and remove by releasing clip.
Remove crash sensor complete with mounting bracket and wiring.
Remove cutaway tape and touch up paintwork as required.
Bolt new crash sensor and mounting bracket in position
1987-88:
Lock washers should be fitted both under and over bracket where tape was removed. Secure bracket by tightening new bolts to 4 Nm (3 ft lb).
1989-:
Use original bolts without washers. Tightening torque: 11 Nm (8 ft lb).
Reconnect connectors and standby power unit
Reconnect connectors at centre console and, on 780, seat belt tensioner connectors.
Reconnect standby power unit connector and install unit.
1988- 760:
740, 780, 940 & 1987 760:
Check for fault codes
Turn ignition key to position II (ignition on). Reconnect battery ground lead and observe SRS warning lamp.
740, 940 & 1987 760:
1988- 760:
780:
Clearing fault code
When fault has been corrected, warning lamp must be cancelled (fault code cleared) to restore normal operation.
Procedure is as follows:
Repeat code display procedure (by grounding test terminal for 2-5 seconds).
Ground test terminal three times within 1.5 to 5 seconds, for at least 0.25 seconds on each occasion. Warning lamp will be extinguished for 4 seconds and relit for 3 seconds to confirm clearance of fault codes. Final extinction of lamp indicates restoration of normal function.
Note: Ground lead must be fitted with spade connectors at both ends. Grounding action must be firm and must not be too brief.
Do not switch off ignition between request and clearance of fault code.
If lamp does not go out
Uncorrected fault is still present. Repeat display procedure, correct fault and repeat clearance procedure.
Install:
- soundproofing panel under steering wheel
- air duct
- carpet
- seat; tighten bolts in floor to 48 Nm (35 ft. lb).