FixVault

Checking alarm function: Notes

Alarm function activation does not work. This means that the horn does not sound and the headlamps and turn signal lamps do not flash.

Cause of fault:

Check that the alarm control module fuses are undamaged. These are located in the fusebox in the cargo compartment.

Checking the alarm control module 

Check the alarm control module connectors. Check for loose connections, contact resistance and oxidation.

Check the cable between the alarm control module and the alarm button. Check for an open-circuit. Check for a short-circuit to ground.

Take readings between terminals #B1 and #B7. The voltage must be approximately 12 V.

Measure the voltage on the alarm control module connector terminal #B4. The voltage should be 12 V.

Checking the alarm button 

Measure the voltage on alarm control module connector #A2 when the alarm button is pressed. The voltage must be approximately 12 V.

Measure the voltage on alarm control module connector #A2 when the alarm button is not pressed. The voltage must be approximately 0 V.

HINT: The alarm button is located under the steering column cover. 

Checking the reset button 

Disconnect the alarm control module 8 pin connector (connector B).

Check the cable between the reset button and connector #B6. Check for a short-circuit to ground.

Measure the resistance of the control module connector #B6 and chassis ground when the reset button is not pressed.

Resistance must be higher than 1 MΩ.

Measure the resistance of the control module connector #B6 when the reset button is pressed. The resistance must be approximately 0 Ω.

HINT: The reset button is located in the cowl in the engine compartment. 

Remedy as necessary.

Other information 

Fig 1: Identifying Connector A Terminals
GLL118014Courtesy of VOLVO CARS OF NORTH AMERICA.
Fig 2: Identifying Voltage Display
GLL101041Courtesy of VOLVO CARS OF NORTH AMERICA.
Fig 3: Identifying Connector B Terminals
GLL118013Courtesy of VOLVO CARS OF NORTH AMERICA.