Component Location
General Description
ECM and TCM give and take various data through CAN communication each other. When the problem of TCM related sensor (input speed sensor, output speed sensor, inhibiter switch, etc.) and actuators (transaxle solenoid valve, etc.) occurs, gear is fixed at 3rd gear position. However, there is no alarming device such as "TCM warning lamp" which notifies drivers of the occurrence of TCM related problem. Therefore if power train related problem happens, Engine check lamp turns ON to let drivers recognize the occurrence of power train system (A/T system) related problem.
DTC Description
U0101 is set when ECM send data requiring signal to TCM, but no return signal is transmitted to ECM within 490ms. This code is due to TCM CAN line related problem or TCM module failure.
DTC Detecting Condition
Item | Detecting Condition | Possible Cause |
DTC Strategy | Signal monitoring
| CAN BUS
CAN communication module component
|
Enable Conditions | IG key ON
|
Threshold Value | CAN BUS communication error.
|
Diagnostic Time | 0.3 sec.
|
Fail Safe | Fuel cut | NO | -
|
EGR Off | NO |
Fuel Limit | NO |
Check Lamp | OFF |
Specification
Communication Format | Digital "0" | Digital "1"( BUS idle ) | Resistance on CAN communication |
High | Low | High | Low | Inside of ECM | IPM |
CAN 2.0B | 3.5V | 1.5V | 2.5V | 2.5V | 120? (20?) | 120? (20?) |
Diagnostic Circuit Diagram
<CAN terminal number of each ECU>
| EMS | TCU | ABS | VDC | EPS | TPMS | Cluster | VGT | Air bag | 4WD | IPM |
CAN HIGH | 68 | 87 | 6 | 14 | 3 | 5 | 2 | 3 | 30 | 5 | 10 |
CAN LOW | 67 | 65 | 13 | 15 | 4 | 6 | 1 | 5 | 20 | 13 | 20 |
Signal Waveform & Data
Fig.1) CAN communication waveform
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 occurrence 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.