Alfa 164 Technical Service Bulletin 45.93.03

Information: Airbag Intermittent Problem Diagnosing

Models: 1991 thru 1993 Spider & 164

Date: 03/05/93

THIS IS A FOLLOW-UP OF PREVIOUS AIRBAG BULLETINS. PLEASE REFER TO TSB # 45.93.01 & 45.93.02,F0R FURTHER INFORMATION.

When putting the Airbag system through a self test to determine whether the fault is a current one, or, an intermittent fault, we advise the following steps to be taken;

  1. Write down the existing fault codes and clear the ECU of them.
  2. Turn the ign. key back on and the Airbag ECU will automatically test the system components and connectors.
  3. If the Airag system displays a current fault, please follow diagnostic procedur:s outlined under that fault code in the respective shop manual.
  4. If the Airbag system shows no fault, the system has experienced an intermittent fault. In this case, please proceed with the following:
  5. Interview the customer as to the circumstances that took place just before the Airbag warning light started flashing.
  6. Inspect undercarriage of vehicle for any signs of damage.
  7. Wiggle and shake, the wire harness related to the Airbag system to try and discover a loose or poor wire, and/or connection. If you can disturb the intermittent problem, the ECU will memorize the fault and cause the warning light to flash, indicating you have located the fault: Correct the fault and then re-test.
  8. If the movement of the wire harness above does not produce a fault code proceed with the following.

FOR codes 14,15,16, 24, 25, 26, ( fender sensor circuit)

  1. With ign. key on wiggle and shake, the wire harness related to the effected Airbag system circuit to try and discover a loose or poor wire, and or connection. If you can disturb the intermittent problem, the ECU will memorize the fault and cause the warning light to flash, indicating you have the located the fault. Correct the fault and then re-test.

    NOTE: For safety reasons, disconnect the battery before beginning an checks or testing of the Airbag system ! Also interupting any circuits while the battery is connected - and the ign. key is on - will produce misleading fault codes.

  2. Unplug and unbolt both front sensors.
  3. Remove paint from surface where sensors mount to improve sensor grounding.
  4. Visually inspect both ends of sensors plug connections and terminals etc. and re-install sensors.
    NOW RE-TEST SYSTEM
  5. Connect the battery, turn on the ign. key. The ECU will begin it's continuous self testing.
  6. With ign. key on wiggle and shake, the wire harness related to the effected Airbag system circuit to try and discover a loose or poor wire, and/or connection. If you can disturb the intermittent problem, the ECU will memorize the fault and cause the warning light to flash, indicating you have the located the fault. Correct the fault and then re-test.

For codes 31, 32, 33, 34, 35, 36, ( Airbag module circuit )

  1. With ign. key on wiggle and shake, the wire harness related to the effected Airbag system circuit to try and discover a loose or poor wire, and or connection. If you can disturb the intermittent problem, the ECU will memorize the fault and cause the warning light to flash, indicating you have the located the fault. Correct the fault and then re-test.

    NOTE: For safetv reasons, disconnect the battery before beginning an checks or testing of the Airbag system ! Also interupting any circuits while the battery is connected - and the ign. key is on - will produce misleading fault codes.

  2. Unplug Airbag ECU from harness visually inspect connections carefully, reconnect and secure lock tabs.
  3. Remove steering column covers, visually inspect connections and follow wires as far as possible into the dash to locate any crushed or pinched wires.
  4. Raise front of car.
    NOW RE-TEST SYSTEM

    CAUTION:Before proceeding with #3,4 & 5, position yourself so you are at arms length and to the side or below the steering wheel. Do not reach thru steering wheel, and keep head clear of Airbag deployment area.

  5. Connect the battery, turn on the ign. key. The ECU will begin it's continuous self testing.
  6. Repeatedly turn steering wheel completely left and right to try and discover a problem within the clockspring and or wiring in that area to cause the ECU to identify a fault.
  7. With ign. key on wiggle and shake, the wire harness related to the effected Airbag system circuit to try and discover a loose or poor wire, and or connection. If you can disturb the intermittent problem, the ECU will memorize the fault and cause the warning light to flash, indicating you have the located the fault. Correct the fault and then re-test.

FOR Codes 41,,42, ( warning light circuit )

  1. With ign. key on wiggle and shake, the wire harness related to the effected Airbag system circuit to try and discover a loose or poor wire, and or connection. If you can disturb the intermittent problem, the ECU will memorize the fault and cause the warning light to flash, indicating you have the located the fault. Correct the fault and then re-test.

    NOTE: For safetv reasons, disconnect the battery before beginning an checks or testing of the Airbag system ! Also interupting any circuits while the battery is connected - and the ign. key is on - will produce misleading fault codes.

  2. Unplug Airbag ECU from harness visually inspect connections carefully, . reconnect and secure lock tabs.
  3. Open instrument cluster and inspect plug connections and follow wires as far as possible into the dash to locate any crushed or pinched wires within dash area, reconnect and secure lock tabs.
    NOW RE-TEST SYSTEM
  4. Connect the battery, turn on the ign. key. The ECU will begin it's continuous self testing.
  5. With ign. key on wiggle and shake, the wire harness related to the effected Airbag system circuit to try and discover a loose or poor wire, and or connection. If you can disturb the intermittent problem, the ECU will memorize the fault and cause the warning light to flash, indicating you have the located the fault. Correct the fault and then re-test.

For code 51, (Faulty Diagnostic ground)

  1. With ign. key on wiggle and shake, the wire harness related to the effected Airbag system circuit to try and discover a loose or poor wire, and or connection. If you can disturb the intermittent problem, the ECU will memorize the fault and cause the warning light to flash, indicating you have the located the fault. Correct the fault and then re-test.

    NOTE: For safetv reasons, disconnect the battery before beginning an checks or testing of the Airbag system ! Also interupting any circuits while the battery is connected - and the ign. key is on - will produce misleading fault codes.

  2. Unplug Airbag ECU from harness, visually inspect connections carefully.
  3. Besure ECU is properly grounded (case bolted down securely),and ground wire attached to one of the mounting bolts.
  4. Reconnect ECU to harness, being sure lock tabs are in place.
    NOW RE-TEST SYSTEM
  5. Connect the battery, turn on the ign. key. The ECU will begin it's continuous self testing.
  6. With ign. key on wiggle and shake, the wlre harness related to the effected Airbag system circuit to try and discover a loose or poor wire, and or connection. If you can disturb the intermittent problem, the ECU will memorize the fault and cause the warning (ight to flash, indicating you have the located the fault. Correct the fault and then re-test.

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