GM Testing - Snap-on

Chapter 8 <strong>GM</strong>
<strong>Testing</strong> Control Systems Tests (Except ABS)
DTC STATUS
SCROLL IN DESIRED TROUBLE CODE TO TEST
*** P1976 ***
THIS VEHICLE DOES NOT SUPPORT THIS DTC!!
Figure 8-20 Sample screen when a DTC is not supported
Automatic Transfer Case (ATC) Codes
The ATC CODES selection displays Automatic Transfer Case (ATC) DTCs (Figure 8-21). The
ATC is optional equipment and this menu selection does not necessarily mean the vehicle is
equipped with an ATC.
CODE LIST
** CODES & DATA. OK TO DRIVE. **
C0323 T-CASE LOCK CIRCUIT LOW
*** END OF LIST ***
Figure 8-21 Sample ATC code list
If the vehicle does not have an ATC, or if there is a communication problem, a “no
communication” message displays (Figure 8-22).
NO COMMUNICATION. MAY NOT BE ATC
EQUIPPED. VEHICLES WITH ATC HAVE
AUTO 4WD SWITCH ON DASH.
PRESS Y TO RETURN TO CODES & DATA MENU.
Figure 8-22 Sample ATC no communication message
Codes (Airbag)
Some older models display DTCs for the supplemental inflatable restraint (SIR), or airbag,
system. However, the airbag control module does not display data parameters. Therefore,
CODES is the only selection available on the MAIN MENU <strong>GM</strong> AIRBAG (Figure 8-23).
MAIN MENU <strong>GM</strong> AIRBAG
>CODES
OTHER SYSTEMS
CUSTOM SETUP
Figure 8-23 Sample early, pre-1994, airbag main menu
Selecting CODES displays the airbag codes (Figure 8-24).
AIRBAG CODES
** DIAGNOSTIC MODE. DO NOT DRIVE **
71 DEFECTIVE DERM
HC HISTORY CODES FOLLOW
Figure 8-24 Sample early, pre-1994, airbag code display
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