GLA-421

HA. DTC 421

Condition





Diagnostic trouble code (DTC) GLA-421 is stored after approximately 2 seconds if the control module registers an error in communication with the glass breakage sensor control module when the alarm system is powered up or when the alarm is activated or deactivated.

Substitute Value
None.

Possible Source
Short-circuit to ground or voltage in communication cable.
Open-circuit in communication cable.
Interference affecting communication cable.
Defective glass breakage sensor.

Fault Symptom(s)
The indicator LED in the sun sensor flashes for 15 seconds when the ignition is switched on.
The system will not trigger the alarm if there is glass breakage in the passenger compartment

Start fault-tracing with HB.

HB1. Erasing Diagnostic Trouble Codes (DTCs)





Ignition on.
Erase diagnostic trouble codes (DTCs).
Then continue with HB2


HB2. Reading Off Diagnostic Trouble Codes (DTCs)

Remove key from ignition switch.
Ensure that all doors, the hood, trunk lid/tailgate are closed.
Lock the car with the remote control.
Wait approximately 10 seconds.
Unlock the car with the remote control.
Ignition on.
Read off diagnostic trouble codes (DTCs).
Does diagnostic trouble code (DTC) GLA-421 recur?
Yes: Go to HB9.
No: Go to HB3.

HB3. Checking Connectors

Ignition off.
Expose VGLA control module.
Remove glove compartment panel and SRS passenger airbag module. Check glass breakage sensor and VGLA control module connectors for contact resistance and oxidation according to WWA5 WW. Checking Wiring and Connections
Ignition on.
Erase diagnostic trouble codes (DTCs).
Then continue with HB4.

HB4. Reading Off Diagnostic Trouble Codes (DTCs)

Remove key from ignition switch.
Ensure that all doors, the hood, trunk lid/tailgate are closed.
Lock the car with the remote control.
Wait approximately 10 seconds.
Unlock the car with the remote control.
Ignition on.
Read off diagnostic trouble codes (DTCs).
Does diagnostic trouble code (DTC) GLA-21 recur?
Yes: Go to HB5.
No: Fault corrected

HB5. Checking Cables





Ignition off.
Check fuse 13.

Hint: If the fuse is blown, check the circuit after fuse 6 for an open-circuit according to WWA2 WW. Checking Wiring and Connections

Check cable between control module #A22 and glass breakage sensor #4 for a short-circuit to ground according to WWA3, short-circuit to supply voltage according to XX and an open-circuit according to WWA2. Check cable between fuse 13 and glass breakage sensor connector #1 for an open-circuit according to WWA2. Check cable between glass breakage sensor #5 and ground for an open-circuit according to WWA2 WW. Checking Wiring and Connections

Other Information:
The voltage between glass breakage sensor connector #1 and ground should be battery voltage.
Remedy as necessary.
Were any faults found in the cables?
No: Go to HB6.
Yes: Go to HB7.


HB6. Replacing Component

Try a new glass breakage sensor.
Then continue with HB7.

HB7. Erasing Diagnostic Trouble Codes (DTCs)





Ignition on.
Erase diagnostic trouble codes (DTCs).
Then continue with HB8


HB8. Verification





Hint: After carrying out the repair, check that the fault has been remedied as follows:

Ignition off.
Reconnect connectors, reinstall components.
Remove the key.
Ensure that all doors, the hood, trunk lid/tailgate are closed.
Lock the car with the remote control.
Wait approximately 10 seconds.
Unlock the car with the remote control.
Ignition on.
Read off diagnostic trouble codes (DTCs).
Does diagnostic trouble code (DTC) GLA-421 recur?
Yes: Fault not found
No: Fault corrected


HB9. Intermittent Fault





Check cable between control module #A22 and glass breakage sensor connectors #4 for an intermittent short- circuit to ground according to WWB3, an intermittent short-circuit to supply voltage according to WWB4 and an intermittent open-circuit according to WWB2. Check cable between fuse 13 and glass breakage sensor connector #1 for an intermittent open-circuit according to WWB2. Check cable between glass breakage sensor #5 and ground for an intermittent open-circuit according to WWB2 WW. Checking Wiring and Connections Operation done