9-3 Convertible (9400) L4-2.0L Turbo (B205) (2000)
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Dimmer Switch: Description and Operation
Rheostat
The rheostat supplies the SID unit with information on the driver's choice of rheostat setting.
The rheostat is a potentiometer which is supplied with +5 V via pin 11 of the control module. The rheostat is grounded through pin 4.
The voltage across the integral rheostat in the SID unit is proportional to the actual resistance of the rheostat, see diagram. The SID unit uses this value
to control the button lighting and calculate the display lighting level.
Information on the rheostat level is sent as bus information, Rheostat level, unit (%).
Diagnostics
An open circuit causes diagnostic trouble code B1736 to be generated.
A short-circuit to ground does not result in a diagnostic trouble code, the rheostat level is at "max" and cannot be altered with the rheostat.
A short-circuit to B+ will destroy the rheostat.
