GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Park Avenue 🢒 Body and Accessories 🢒 Stationary Windows 🢒 Defoggers and Heated Mirrors Always On

Step

Action

Value(s)

Yes

No

1
  1. Connect the Scan Tool .
  2. Turn the ignition to RUN.
  3. Turn the rear defogger ON.
  4. Display the SBM outputs.

Is the rear defogger being requested on?

--

Go to Step 2

Go to Defogger System Check

2
  1. Disconnect the HVAC control assembly.
  2. Connect a test lamp between HVAC control assembly connector terminal B1 and ground.

Refer to

Cell 68: IP Fuse Block


Object Number: 377200 Size: FS
HVAC Components
HVAC Temperature Controls Circuit Description
Cell 68: Temperature Controls
Cell 10: BATT 1, RDM, C/LTR, DDM, HTDST L, TRK REL, PDM, SBM, and CSTR/SBM Fuses
Cell 10: WSW, WSW/RFA, HUD, ELC, CR CONT, A/C and HVAC Fuses
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Cell 50: Power, Ground and E&C Serial Data Line
Cell 150: Radio
HVAC Connector End Views
 in HVAC and refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp light?

--

Go to Step 3

Go to Step 4

3
  1. Check for proper terminal contact at the HVAC control assembly. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
  2. If OK, replace the HVAC control assembly. Refer to Control Assembly Replacement

Was the control assembly replaced?

--

System OK

--

4
  1. Check for proper terminal contact at the HVAC programmer. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
  2. If OK, replace the HVAC programmer. Refer to Programmer Replacement

Was the programmer replaced?

--

System OK

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