GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1998 🢒 DeVille 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 Diagnostic Trouble Code (DTC) Displaying

The diagnostic trouble codes (DTCs) may be displayed by using either of the following diagnostic tools:

    • The Scan Tool
    • The on-board diagnostics

Perform the following steps in order to display the DTCs using the Scan Tool:

  1. Select ACM.
  2. Select DTC.
  3. Select one of the following DTCs:
    4. • CURRENT
    • HISTORY

Perform the following steps in order to display the DTCs using the on-board diagnostic method:

  1. Press one of the following combinations:
    2. • For digital IPC, press OFF and WARMER.
    • For analog IPC, press OFF and PASSENGER WARMER.
  2. Press the LO (fan speed) button until ACM? appears.
  3. Press the HI (fan speed) button until ACM CODES? appears.
  4. Press the HI (fan speed) button until ACM DTC appears.