General Motors OBD II Scan Tool Interface GM Scan Tool General Motors OBD II Scan Tool Interface Single Interface Accesses Both Manufacturer-Specific and Generic OBD II Functions

Initial Display F0: Diagnostics - Contains various submenus used to perform diagnostic functions (look at DTCs, Freeze Frame, etc.) F1: Service Programming - Reflashing PCM F2: View Captured Data - Allows you to view any Captured Snapshot Information

Main Menu F0: Diagnostic Trouble Codes (View DTCs) F1: Data Display (View the data display for Engine/Transmission) F2: Special Functions (takes you to Output Controls) F3: Snapshot (allows you to take a snapshot movie of data) parameters around a trigger) F4: System Information (Readiness Status of Monitors) F5: ID Information (displays calibration ID and VIN)

Selecting Engine or Transmission Data Data parameters are grouped by Engine (F0) and Transmission (F1). Data displays for the engine and transmission are presented in two separate groups Select the F0 or F1 keys to select Engine or Transmission

DTC Information F0: DTC Information lets you look at all stored DTCs F1: Specific DTC lets you view an individual DTC by entering its number F2: Freeze Frame/Failure Records takes you to a list of all stored Freeze Frame and Failure Records F3: Clear DTC Information lets you erase DTCs and FF/FR F4: Diagnostic Test Status takes you to a list that shows the current status of tests that stored Freeze Frame or Fail Records

F0: DTC Information In addition to allowing you to look at any History Codes, this menu lets you determine WHEN the test failed. Use this menu to help you determine if: the DTC set since DTCs were cleared, the test has run and failed it has run and failed this ignition

DTC Display If a Specific DTC is selected, a display shows its number, a brief description of the DTC, and the test status Use the test status information to tell you if the test has run, and whether or not the test passed or failed

Freeze Frame/ Failure Records This Application Menu display is an important one since it contains so many diagnostic options related to system faults (DTCs, FF, FR, etc.) For example, we can select: F2: Freeze Frame/ Failure Records

Freeze Frame (FF) Failure Records (FR) The Freeze Frame/ window shows the Freeze Frame for a DTC that turned on the MIL, and a list of all Fail Records Cursor down to select the data to view and hit Enter, or select the function key corresponding to the FF or FR you want to view (F0, F1, etc.)

Freeze Frame Data This is the mandated Freeze Frame data required by OBD II regulations Note that fuel trim is displayed in both percent and in the traditional GM Fuel Trim Counts

Failure Records Failure Record data looks like Freeze Frame. It is a diagnostic enhancement that stores data for as many as many as five separate faults Failure Records are the most current diagnostic information and, unlike Freeze Frame, can be updated by the PCM

Clearing DTCs Choose Clear DTC Information to erase all DTCs from memory This will erase all DTCs and Freeze Frame, and on 1997 and later GM vehicles it will reset all Readiness Flags 1995-96 GM vehicles reset only the monitor(s) related to the DTC(s)

Clear DTC Information You’ll be prompted with a Yes/No choice before DTCs are erased DO NOT erase DTCs unless you have saved Freeze Frame data, or you’ll lose it. Freeze Frame (FF) is cleared with the DTC information

Diagnostic Test Status Selecting Diagnostic Test Status To view the current status of a fault-related test, use the Up/Down Arrow Keys to highlight the selection and hit Enter, or push the F4 key This will take you to the Diagnostic Test Status Display

Diagnostic Test Status The Diagnostic Test Status display lists all FF and FR and their test status Yes/No in the RAN column tells you if the test ran Yes/No in the FAIL column indicates Pass/Fail status INT suggests the possibility of an intermittent Use this information before, during, and after repairs to evaluate system status

Data Display Data Parameters are grouped into four main categories Engine data parameters are broken into two groups (Engine Data 1 and 2) on vehicles with a large parameter list and some parameters may appear on both lists Use the groups to concentrate on areas of concern (e.g. EGR concerns versus misfire)

Data Parameters Use the white boxes at the bottom of the display to: Select Items from the data display list for viewing and recording Go directly to DTCs Capture Data using the snapshot feature The More choice sends you to other menu options

Special Functions Want to get to those bidirectional controls? The ones we call Output Tests? Select Special Functions from this menu

Output Controls There are several submenu options that allow you to go to subsystems and activate various components To select Engine Output Controls, hit F0 or hit the Enter key with F0 highlighted as shown

Engine Output Controls Menu This display shows a number of components that you can activate through the scan tool to test their performance You can use this menu to test the bulb in the MIL, operate the fuel pump and cooling fans, etc.

Output Test - Fan Relay The ON/OFF boxes at the bottom of the screen are used to command the component In addition, parameters of your choice (Select Items) can be viewed during the test

EVAP Purge Solenoid Other types of output controls enable you to activate a pulse width modulated component like the EVAP Purge Solenoid and look at the system response Here, we’re watching fuel tank pressure and fuel trim as we gradually open the purge using the Decrease and Increase control buttons

Fuel and IAC Controls You can also concentrate on the Fuel or IAC Systems Fuel system controls allow injector balance tests and IAC control Separate menu choices let you reset adaptive fuel trim and IAC learned values during or after a repair without having to disconnect the battery

Summary GM supports all Generic OBD II functions Individual data parameters can be viewed These parameters are located in groups (Engine 1, Engine 2, etc.) Various output tests are available, including tests of individual components In addition to Freeze Frame, the PCM provides GM-specific enhancements: Failure Records, DTC Information, and Diagnostic Test Status display