DTC U1144: Loss Of Serial Communications - PHN: Description

Class 2 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 send a State of Health (SOH) message every 5 seconds to other systems. If those systems fail to send an SOH message back, a corresponding DTC will be set.

DTC U1144 will set when IPC has sent an SOH message to cellular phone (PHN), and no SOH message response was sent back for 3 consecutive monitoring cycles. When DTC U1144 is set, PHONE NOT PRESENT message will display on driver's message center when phone steering wheel control button is pressed. DTC U1144 will clear when PHN transmits a SOH message to IPC.