Accessing and Reading Diagnostic Trouble Codes

SCAN/TECH 1 TOOL DIAGNOSTICS
A SCAN/TECH 1 tool can be used to read current codes and history codes. The tool must be updated to communicate with the SIR system through a replaceable cartridge or a manufacturer's update before it can be used for SIR diagnosis. To use the SCAN/TECH 1 tool, connect it to the ALDL connector and turn the ignition switch On. Follow the tool manufacturer's instructions for communication with the SIR system.

FLASH CODE DIAGNOSTICS
Flash codes diagnostics can only be used to read current codes and to determine if history codes exist. To read current codes, ground terminal K of the ALDL connector with the ignition switch On.
The DERM displays the trouble codes by flashing the SIR warning lamp. Each code that is displayed will consist of a number of flashes which represents the first digit, followed by a 1/2 second pause, followed by a number of flashes which represent the second number. An example of trouble code 41 would be four flashes, followed by a 1/2 second pause, followed by one flash.
Each code is flashed once until all codes are displayed. The code sequence will repeat until terminal K of the ALDL connector is no longer grounded.
Two special codes exist when reading the flash codes. Code 12 will always be displayed when the flash codes are enabled. Code 12 is not an indication of a fault, but an indication that flash code mode has been started. Code 13 will be displayed only if no history codes are in memory. To read history codes, a SCAN/TECH tool must be used.