SRS Sensor Harness - Replacement Procedure

Group 72
Equipment and Accessories

Bulletin Number
72 03 88 (1647)

Woodcliff Lake, NJ
September 1989
Technical Dept.

This Service Information bulletin supersedes S.I. 72 03 88 (1647) dated May 1988. Revisions to the repair procedures have been made. Please remove and discard S.I. 72 03 88 (1647) dated May 1988 from your S.I. binder.

SUBJECT:
SRS Front Crash Sensor Harness Replacement

MODELS:
E32, E34

Situation:
If the connectors or wires of the SRS front crash sensors are found to be defective or damaged, the crash sensor wiring must be replaced. Repairs to the wiring/connectors must not be attempted.

For this reason a replacement SRS front crash sensor harness is available under P/N 61 12 1 378 295.

To accommodate this replacement harness, the vehicle is already equipped with access holes (from the factory). Detailed installation procedures for this harness follow.

Vehicle Preparation





^ Disconnect negative battery cable and cover the negative post with a shop rag.

^ Remove lower left dash panels.

^ Remove knee bolster.

^ Disconnect X784 as shown.

^ Remove left wiper arm.

^ Remove left cowl cover.

^ Remove front power distribution box cover.





^ Locate the inside of the firewall grommet (behind the instrument cluster).

^ Pull the grommet backing plate out of the grommet.

^ Carefully cut out the large diameter hole in the grommet.

Harness Routing





^ Pull the sensor leads out of the grommet. Retain the grommet for possible use later in this installation.





^ Pull the sensor leads through the firewall grommet.

^ Snap the rubber grommet into place by pulling on its "ears".

Note:
Make sure this grommet is fully seated.

Failure to do this can lead to water intrusion into the passenger compartment.





^ Install the grommet backing plate as shown.

^ Disconnect the orange 6-pin X75 connector from the SRS control unit. Cut this connector off where it enters the vehicle harness.





^ Connect the new 6-pin X75 connector to the SRS control unit.

^ Locate knockout plug on the engine compartment partition.

NOTE:
If the grommet is present in this location, it is not necessary to install a new one.

^ Remove the insulating material with a knife.





^ Remove the metal plug by gently tapping with a hammer.





^ Insert the rubber grommet as shown which was previously removed from the sensor harness.

^ Route the sensor leads through the grommet backing plate.

^ Route the sensor leads through the grommet.

^ Push the backing plate into the grommet.

^ Remove the four 10 mm plastic nuts which retain the metal harness shroud to the firewall.





^ Route the right front sensor lead as shown placing the lead under this shroud.

NOTE:
Do not route the harness where it can contact any sharp edges. Secure the harness with cable ties as shown.

^ Route the left front lead as shown avoiding any sharp edges. Secure lead with cable wraps as shown.

^ Cut off the old crash sensor connectors (X81 and X86) where they enter the vehicle harness.

^ Reinstall components previously removed.

^ Re-connect negative battery cable.





^ Re-connect X784.