DTC 43A21 - Electric Detonator 1 Open Circuit

MALFUNCTION
Diagnostic trouble code 43A21: Electric detonator 1, open circuit.

DIAGNOSTIC PROCEDURE
1. Unscrew the steering wheel airbag module and unplug the connector at the rear of the airbag. Plug reference resistor 84 71 153 into the connector.

NOTE: For cars with a passenger side airbag: Remove the lower cover and unplug the airbag connector H2-80. Plug reference resistor 84 71 153 via cable 86 11 378 into the connector.

2. Switch ON the ignition and clear the trouble code. Switch the ignition OFF and then ON again. Wait at least 40 seconds with the ignition ON. Check whether the trouble code recurs.
If the trouble code recurs - proceed to point 3. If the trouble code does not recur, the fault is in the steering wheel airbag module. Switch OFF the ignition and carry out a double check by plugging in the airbag. Switch ON the ignition and wait at least 40 seconds with the ignition ON. Check whether the trouble code recurs (the airbag may have had a poor connection).
If the trouble code recurs, switch OFF the ignition and change the airbag. Switch ON the ignition and clear the trouble code. Switch the ignition OFF and then ON again. Wait at least 40 seconds with the ignition ON. Check whether the trouble code recurs.
3. Unplug connector from control module 331 and check pins 17 and 18 for continuity and/or slide-out
4. Plug in the connector- clear the trouble code and wait at least 40 seconds with the ignition ON. Then check whether the trouble code recurs If the trouble code does not recur - the fault was in the connector.
If the trouble code does recur proceed to point 4.
5. Unplug connector H2-52 (H2-77) and check the pins and sockets for continuity and/or slide-out
6. Plug in the connector- clear the trouble code and wait at least seconds with the ignition ON. Then check whether the trouble code recurs.
If the trouble code does not recur the fault was in the connector.
If the trouble code does recur proceed to point 5.
7. Unplug connector H2-52 (H2-77) and unplug reference resistor 84 71 153 from the steering wheel airbag connector Change the contact unit- plug in the connector and plug in the reference resistor again.
8. Clear the trouble code and wait at least 40 seconds with the ignition ON. Then check whether the trouble code recurs.
If the trouble code does not recur - the fault was in the contact unit.
If the trouble code does recur - the fault is in the wiring between connector H2-52 (H2-77) and the connector at the control module. Investigate the cause. Rectify the fault or change the wiring as necessary.