General Information

Smart Cruise Control

C1646 CAN signal error TCU - General Information

Component Location





General Description

VSM (Vehicle Stability Management) system is a safety system to reduce damage by using ESP, PSB (Pre-safe Seat Belt), SCC, Cluster under condition of a collision predicted. VSM control mechanism 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.

DTC Description

SCC sets this code when the messages (TCU2) from TCM was not received within the last 500 msec or improper message, checksum detected. System recovers to normal state if the message is received again.

DTC Detecting Condition





Diagnostic Circuit Diagram










Signal Waveform & Data




Monitoring CAN HIGH and LOW simultaneously is important in monitoring CAN communication waveform. When CAN HIGH signal rise to 3.5 V and LOW signal drops to 1.5 V - voltage difference between HIGH and LOW signal is 2 V - at BUS IDLE state (DIGITAL "1") whose reference voltage is 2.5 V, "0" is recognized. Besides, comparing HIGH and LOW signal if opposite waveform is detected with the reference voltage of 2.5 V, 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.