Antitheft and Alarm Systems

DTC (DIAGNOSTIC TROUBLE CODES)

The Instrument Panel Cluster may, under certain circumstances, set it's own Diagnostic Trouble Codes (DTCs) over the Universal Asynchronous Receiver Transmitter (UART) Data Line. These can be found by using the "DTC" mode of the TECH 1. The first instance a DTC could be set is for Vehicle Theft Deterrent operation. Refer to THEFT DETERRENT SYSTEMS for system and code diagnosis and operation. Antitheft and Alarm Systems The second instance is when there is a loss of serial data with one or more of the Modules on the UART Data Line. Such a loss could be the result of an open or short in the UART Data Line or CKT 800. These codes can be especially useful when diagnosing an intermittent problem. An explanation of these are given below. Refer to DATA LINK CONNECTOR, CHART #1 for UART Serial Data Line diagnosis.

DTC 21 LOSS OF PCM SERIAL DATA - The IPC is having trouble communicating with the Powertrain Control Module (PCM).

DTC 22 LOSS OF SIR SERIAL DATA - The IPC is having trouble communicating with the Sensing Diagnostic Module (SDM).

DTC 23 LOSS OF ABS SERIAL DATA - The IPC is having trouble communicating with the Electronic Brake Control Module (EBCM).