VSM(Vehicle Stability Management) system is a safty system to reduce damage by using ESP, PSB(Pre-safe Seat Belt), SCC, Cluster under condition of a collision predicted. VSM control mecanism is as follows.
1. Preceding vehicle approaching : Cluster turns on yellow warning lamp.
2. Preceding vehicle approaching too close : ESP prepares breaking and PSB vibrates belt, Cluster turns on red warning lamp to inform danger to driver.
3. Under condition of a collision predicted : PSB retracts seat belt fully, ESP slows down the car and assist driver to make a proper break force according to situation.
SCC monitors CAN messages from ESP. SCC sets this code when abnormal message is received from ESP. System recovers to normal condition as soon as the signal is alright again.
Item
Detecting Condition
Possible cause
DTC Strategy
CAN message monitoring
Faulty SCC
ESP system error
Open in harnesses between SCC and ESC
Enable Conditions
Engine Run (engine rpm higher than 400 at least for 2s)
Threshold value
Abnormal CAN message from ESP is detected
Diagnosis Time
-
Recover Condition
As soon as the normal message is received again
Fail Safe
Red VSM2 warning lamp turns on
Red SCC warning lamp turns on
Monitoring CAN HIGH and LOW simultaneously is important in monitoring CAN communication waveform. When CAN HIGH signal rise to 3.5V and LOW signal drops to 1.5V - voltage difference between HIGH and LOW signal is 2V - at BUS IDLE state(DIGITAL "1") whose reference voltage is 2.5V, "0" is recognized. Besides, comparing HIGH and LOW signal if opposite waveform is detected with the reference voltage of 2.5V, Check if current cam signal transfers correctly. Continuous "0"signal above 6BIT means the occurence of error in CAN communication. 1BIT is easily distinguished as calculating the time when "SOF"(START OF FRAME) which notifies the start of frame occurs. Check if "0"signal above 6BIT is detected continuously when monitoring CAN communication waveform.