DTC U1040: Loss Of Communication With TCS: Description

Serial data circuit is used to communicate information between systems. Each system on the serial data line is assigned its own recognition code, which is used to identify which system is communicating. Systems periodically send a State of Health (SOH) message to other systems. If those systems fail to send an SOH message back, a corresponding DTC will be set. Also, any system that cannot communicate properly will set the corresponding DTC.

DTC U1040 will set when IPC has sent an SOH message to Traction Control System (TCS), and no SOH message response was sent back for 5 seconds. No driver warning message will be displayed.

DTC U1040 requires an ignition cycle to change from current to his-tory. If conditions for malfunction no longer exist, history DTC will clear after 50 consecutive ignition cycles. DTC U1040 will also clear when conditions no longer exist, or when IPC or scan tool is used to clear codes.

NOTE: If DTC U1040 is a history code, problem may be intermittent. Wiggle wires while performing the following test.