Control Module Does Not Switch Off Light
When the MOST network is requested to sleep, the Control Display switches off the light in the MOST ring. The lack of light input is a signal to the individual control modules to switch off their light output and enter sleep mode.
If a control module does not switch off its light, all down stream control modules register the fault "A Control Module is not switching light off."
IMPORTANT:
Failure of a control module to turn its light off, will cause the MOST network NOT to enter sleep mode. If the MOST network fails to sleep, the rest of the car will not be able to enter sleep mode. This will lead to battery discharge.
To diagnose, read out fault memory in MOST ring order.
The fault lies in the control module that precedes the module where the fault is first stored.
Always confirm the problem by first clearing the fault and performing the diagnosis a second time. If the same results occur, replace the defective control module.