Airbag DM Fault Code 14

Airbag DM Fault Code 14

Primary crash sensor circuit short to ground

Normal Operation

The diagnostic module measures the voltage at pins
1-2 and 1-6. The normal voltage at these pins is 10
vols (±1 volt) with the ignition on, and battery
voltage with the ignition off.

If the voltage at the airbag diagnostic module connector pins 1-2 or 1-6 drops below 5 volts, fault code 14 will be generated and the airbag warning lamp will be switched on. When generating a code 14 the diagnostic module also generates a signal to blow its own internal thermal fuse. This action disables the airbag deployment circuit. The airbag diagnostic module fuse is non-repairable and the module must be replaced after removing the short circuit. If the voltage at pins 1-2 and 1-6 returns to normal, fault code 51 (blown thermal fuse) will be logged.

Fault Analysis

WARNING: Read and adhere to all warnings and safety procedures at the start of this section when working on the airbag system.

1. Disarm the airbag system and fit airbag simulators (6.4.21.4)
2. Disconnect the airbag diagnostic module and remove the plastic wedge from plug 1 (slate).

Note: The plastic wedge contains a shorting bar which would short together pins 1-3 (gnd), 1-11 and 1-2 when the plug is disconnected.

1. Measure the continuity to ground at the following pins on the diagnostic module harness connector:
2. 1-2 RH crash sensor monitor
3. 1-11 LH crash sensor feed
4. 1-6 LH crash sensor monitor
5. 1-12 RH crash sensor feed

If no short circuit is detected, go to step 4.

If a short circuit is detected, disconnect the relevant crash sensor and repeat the continuity measurement to isolate the circuit fault. Service the wiring or replace the crash sensor as necessary. Refit the plastic wedge to the diagnostic module connector. Fit a new airbag diagnostic module and rearm the airbags (6.4.21.4).

Airbag DM Fault Code 21

Safing sensor insecure mounting.

Normal Operation

The diagnostic module measures the resistance between pins 1-10 (safing sensor case ground) and 1-3 (monitor reference ground) at the diagnostic module connector. If the resistance is greater than 2Ω a fault code 21 will be generated and the airbag warning lamp will be switched on.

Note: a good ground connection is vital. The wire from pin 1-1 is riveted to the safing sensor case and the case must be securely grounded to the vehicle body.

Fault Analysis

WARNING: Read and adhere to all warnings and safety procedures at the start of this section when working on the airbag system.

1. Disarm the airbag system and fit airbag simulators (6.4.21.4).
2. Disconnect the diagnostic connector and check for continuity from pin 1-3 to chassis ground.

If continuity is good, go to step 3.

If the resistance reading is 2Ω or more, service the diagnostic module ground circuit to pin 1-3 as necessary. Confirm a good ground path between pins 1-10 and 1-3. Clear the code 21 and rearm the airbags (6.4.21.4).

1. Check for continuity between pins 1-10 and chassis ground at the safing sensor.

If the resistance is above 2Ω, check for continuity from the safing sensor connector pin 5 to chassis ground. Also check the safing sensor mounting for corrosion, dirt or loose fixings. Service the wiring and/or clean and secure the sensor mounting as necessary. If a satisfactory ground is not achieved, replace the safing sensor.

2. Make a final continuity test from diagnostic module connector pin 1-3 to 1-10 to ensure a satisfactory ground path. Reconnect the diagnostic module. Clear the code 21. Rearm the airbags (6.4.21.4).