The ECM communicate over the CAN are with EMS(Engine Management System), TCS(Traction Control System), TCM(Transmission Control Moudle).
The TCM monitors various information such as vehicle speed , gear position and engine torque during upshift, it requests the ECM to retard ignition timing to decrease torque.
This produces small change in torque during upshift, hence smooth shift and increase in shift feeling.
In case of the TCM failure, the engine symptoms will occur a corrupted torque reduction signal information,a shift shock, a increasing engine rpm abruptly.
If the CAN communication generates threshold value, the ECM judged this as a fault and DTC is set.
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Signal check, high and low | ● Open in signal circuit ● Short to ground in signal circuit ● Faulty TCM ● Faulty ECM |
Enable Conditions | ● Ignition on | |
Threshold Value | ● No signal through CAN communication lines. | |
Diagnostic Time | ● 1 sec. | |
MIL Fuel Limit Fuel Cut EGR Off | ● No ● No ● No ● No |
