GM Service Manual Online
For 1990-2009 cars only

Stop Lamps Inoperative Pickup

Step

Action

Value(s)

Yes

No

DEFINITION: This diagnostic should only be used if all brake lamps are inoperative.

1

Did you perform the Exterior Lights System Check?

--

Go to Step 2

Go to Exterior Lights System Check

2

Disconnect the Stop, TCC, and Cruise Switch. Measure voltage at pin B of the connector.

Was voltage present?

V

Go to Step 4

Go to Step 3

3

Repair open in Ckt 140 (ORN). Refer to Wiring Repairs in Wiring Systems.

Is repair complete?

--

Go to Exterior Lights System Check

--

4

Depress the Brake pedal while measuring continuity from pin A to pin B of the connector.

Is conitnuity present?

ohms

Go to Step 6

Go to Step 5

5

Replace the Stop, TCC, and Cruise Switch. Refer to in Hydraulic Brakes

Is the repair complete?

--

Go to Exterior Lights System Check

--

6

  1. Reconnect the connector at the Stop, TCC, and Cruise Switch.
  2. Disconnect the connector at the Brake Lamp Relay.
  3. Measure voltage at D7 of the relay connector.

Is voltage present?

V

Go to Step 8

Go to Step 7

7

Repair open in Ckt 17 (WHT). Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Exterior Lights System Check

--

8

  1. Reconnect the connector at the Brake Lamp Relay.
  2. Disconnect the connector at the Directional Signal Switch.
  3. Apply the Brake Pedal.
  4. Measure voltage at pin E2 of the Directional Signal Connector.

Is voltage present?

V

Go to Step 9

Go to Step 10

9

Replace the Directional Signal Switch. Refer to Turn Signal and Multifunction Switch Assembly - Disassemble - Off Vehicle in Steering.

Is the repair complete?

--

Go to Exterior Lights System Check

--

10

Inspect for an open in Ckt 20 (LT BLU). Refer to Wiring Repairs in Wiring Systems

Was an open found?

--

Go to Step 11

Go to Step 12

11

Repair the open in Ckt 20 (LT BLU). Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Exterior Lights System Check

--

12

Replace the Brake Lamp Relay.

Is the repair complete?

--

Go to Exterior Lights System Check

--

Stop Lamps Inoperative Suburban/Utility

Step

Action

Value(s)

Yes

No

DEFINITION: This diagnostic is only to be used when the rear stop lamps are all inoperative.

1

Was the Exterior Lights System Check performed?

--

Go to Step 2

Go to Exterior Lights System Check

2

Disconnect the Stoplamp, TCC, and Cruise Control Switch Connector. Measure voltage at pin B.

Was there voltage?

V

Go to Step 4

Go to Step 3

3

Repair the open in CKT 140 (ORN). Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Exterior Lights System Check

--

4

Depress the Brake pedal and measure continuity across Pin A and Pin B.

Was there continuity?

ohms

Go to Step 6

Go to Step 5

5

Replace the Stoplamp, TCC, and Cruise Control Switch.

Is the repair complete?

--

Go to Exterior Lights System Check

--

6

  1. Reconnect the Stoplamp, TCC, and Cruise Control Switch Connector
  2. Disconnect the Directional Signal Switch Connector.
  3. Depress the Brake Pedal
  4. Measure voltage at A1 of the connector

Was voltage present?

V

Go to Step 8

Go to Step 7

7

Repair the open in CKT 17 (WHT). Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Exterior Lights System Check

--

8

Replace the Directional Signal Switch.

Is the repair complete?

--

Go to Exterior Lights System Check

--