PRE-RELEASE
Steering wheel controls
| Steering wheel controls |
| General |
The steering wheel control consists of 3 units (7 connectors) which are mounted in the steering wheel and airbag control module. The steering wheel control provides SID with information regarding activated connectors.
SID supplies power to the steering wheel control with +5V via pin 22 and grounding 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 connector 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 -
|
1.2
|
160
|
|
VOL +
|
1,7
|
242
|
|
SRC (select audio source)
|
2,1
|
347
|
|
SEEK >>
|
2,5
|
494
|
|
<< SEEK
|
2,9
|
709
|
|
NXT (settings for audio sources)
|
3,3
|
1041
|
|
Normal
|
4,0
|
2511
|
SID uses the information to activate the horn and send audio function bus information.
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.
