GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 Savana 🢒 Body and Accessories 🢒 Lighting Systems 🢒 HVAC Switch Lamp Inoperative

HVAC Switch Lamp Inoperative Cargo Van - Front

Step

Action

Value(s)

Yes

No

1

Was the Interior Lights Dimming System Check performed?

--

Go to Step 2

Go to Interior Lights Dimming System Check

2
  1. Place the headlamp switch in the park lamps position.
  2. Observe that the parking lamps operate.
  3. Adjust the instrument panel (IP) dimmer switch thumbwheel to a mid-range position.
  4. Disconnect connector C1 at the heater and air conditioning (A/C) controller.
  5. Connect an unpowered test lamp between the heater and A/C controller connector C1, cavity C for CKT 8 (GRY), and ground.

Does the test lamp light?

--

Go to Step 4

Go to Step 3

3

Repair the open in CKT 8 (GRY) between splice S223 and the heater and A/C controller.

Is the heater and A/C controller lamp operative?

--

Go to Interior Lights Dimming System Check

Go to Step 4

4

Connect a J 39200 DMM between heater and A/C controller connector C1, cavity B for CKT 150 (BLK), and ground.

Is continuity present?

--

Go to Step 5

Go to Step 6

5

Replace the heater and A/C controller.

Is the heater and A/C controller lamp operative?

--

Go to Interior Lights Dimming System Check

--

6

Repair the open in CKT 150 (BLK) between ground G201 and the heater and A/C controller.

Is the heater and A/C controller lamp operative?

--

Go to Interior Lights Dimming System Check

--

HVAC Switch Lamp Inoperative Passenger Van - Front

Step

Action

Value(s)

Yes

No

1

Was the Interior Lights Dimming System Check performed?

--

Go to Step 2

Go to Interior Lights Dimming System Check

2
  1. Place the headlamp switch in the park lamps position.
  2. Observe that the parking lamps operate.
  3. Adjust the instrument panel (IP) dimmer switch thumbwheel to a mid-range position.
  4. Disconnect the connector at the front auxiliary heating, ventilation and air conditioning (HVAC) control module.
  5. Connect an unpowered test lamp between the front auxiliary HVAC control module connector, cavity A for CKT 8 (GRY), and ground.

Does the test lamp light?

--

Go to Step 4

Go to Step 3

3

Repair the open in CKT 8 (GRY) between splice S223 and the front auxiliary HVAC control module.

Is the front auxiliary HVAC control module lamp operative?

--

Go to Interior Lights Dimming System Check

Go to Step 4

4

Connect a J 39200 DMM between front auxiliary HVAC control module cavity B for CKT 150 (BLK), and ground.

Is continuity present?

--

Go to Step 5

Go to Step 6

5

Replace the front auxiliary HVAC control module.

Is the front auxiliary HVAC control module lamp operative?

--

Go to Interior Lights Dimming System Check

--

6

Repair the open in CKT 150 (BLK) between ground G400 and the front auxiliary HVAC control module.

Is the front auxiliary HVAC control module lamp operative?

--

Go to Interior Lights Dimming System Check

--