Steering wheel controls
Steering wheel controls |
General |
The steering wheel controls consist of 3 units (7 switches) mounted in the steering wheel and airbag module. The steering wheel controls provide the SID with information on switches are activated.
The SID supplies the steering wheel controls with +5V via pin 22 and grounds them via pin 9.
The 7 steering wheel switches consist of 7 resistors connected in series. When a button is pressed, the switch concerned is grounded, see table below.
When a switch is pressed, the total resistance in the circuit changes, as does the voltage value which SID then reads.
The horn switch (41) is connected in parallel with the steering wheel switches and when it is pressed, pin 22 is grounded direct to pin 9.
The table shows the correlation between the voltage on pin 22 and the switch that is activated.
Switch
|
Voltage (V)
|
Resistance (ohms)
|
Horn
|
0
|
0
|
VOL -
|
0.7
|
82
|
VOL +
|
1.2
|
164
|
SRC (select audio source)
|
1.8
|
284
|
SEEK >>
|
2.4
|
464
|
<< SEEK
|
3.0
|
794
|
NXT (settings for audio sources)
|
3.6
|
1474
|
Normal
|
4.2
|
3674
|
The SID uses the information to activate the horn and send bus information for the audio functions.
On cars without steering wheel controls (cars without audio system), only the steering wheel switch for the horn is used.
Diagnostics |
In the event of a break/short to B+ or short-circuit to ground for more than 5 minutes, diagnostic trouble code B2371 will be generated. This applies only to cars with the Saab Audio System having steering wheel controls.