Airbag DM Fault Code 33

Airbag DM Fault Code 33

Passengers airbag circuit high resistance or open circuit.

Normal Operation

The diagnostic module measures the resistance across pins 2-2 and 2-3 every time the ignition is switched on. The resistance should be 0.9 to 1.1Ω. If the total resistance in the passengers airbag circuit exceeds 4.0Ω, fault code 33 will be declared and the airbag lamp will be illuminated.

Note: The nominal resistance of the airbag simulator is 2.5Ω, therefore expect a total circuit resistance reading of 2.4 - 2.6Ω with the simulator fitted.

Caution: The passenger airbag connector contains shorting bars which short circuit pins 1 and 3 of both sides of the connector when disconnected.

DO NOT REMOVE THE AIRBAG SHORTING BAR UNDER ANY CIRCUMSTANCES.

The harness shorting bar may be temporarily removed during the following resistance checks.

Possible Causes

• Open circuit or high resistance in the wiring harness
• Open circuit or high resistance in the passenger airbag module.
• Defective diagnostic module

WARNING: Do not attempt a direct resistance check on the airbag module. Accidental deployment can occur due to the induced voltage from the measuring equipment.

Fault Analysis

1. Disarm the airbag system and fit airbag simulators (6.4.21.4).
2. Disconnect the diagnostic module and remove the plastic wedge from connector 2 (black). Measure the resistance between pins 2-2 and 2-3. The resistance should be 2.4 - 2.6Ω.

If the resistance is 2.4 - 2.6Ω, go to step 3.

If the resistance is not in the range 2.4 - 2.6Ω, isolate the continuity problem noting the following:

1. In the diagnostic module connector, pin 2-2 is shorted to pin 2-3 by a shorting link when plug 2 of the diagnostic connector is removed. Removal of the plastic wedge from the plug will remove this short circuit.
2. At the airbag module harness connector, pin 1 is shorted to pin 3 when the airbag is disconnected. Removal of the plastic wedge from the plug will remove this short circuit.
3. The shorting link fitted in the airbag module connector will short pin 1 to pin 3 when the airbag is disconnected. Do not attempt to remove this shorting link or the plastic wedge. Do not attempt to measure the resistance of the airbag module.
4. Carefully replace all plastic wedges on completion of the circuit checks.

3. The fault is therefore in either the airbag module or in the airbag diagnostic module.

Substitute a known good diagnostic module. If code 33 recurs with the airbag simulator fitted, there is still a fault in the wiring or the simulator.

If the fault code 33 does not recur, rearm the airbags (6.4.21.4) and retest.

If fault code 33 recurs with the airbag module fitted, the airbag module is faulty. Replace the passengers airbag module (7.8.02.6).