GM Service Manual Online
For 1990-2009 cars only

Step

Action

Values

Yes

No

1

Check fuse F5.

Is fuse F5 blown?

--

Go to Step 2

Go to Step 3

2

  1. Check for a short circuit and repair it, if necessary.
  2. Replace the fuse.

Is the repair complete?

--

System OK

--

3

Use a voltmeter to check the voltage at fuse F5.

Is the voltage at F5 equal to the specified value?

11-14 V

Go to Step 5

Go to Step 4

4

Repair the power supply circuit for fuse F5.

Is the repair complete?

--

System OK

--

5

  1. Press the brake pedal.
  2. Check the positive terminals of the bulb sockets with a test lamp.

Does the test lamp illuminate?

--

Go to Step 6

Go to Step 8

6

Connect an ohmmeter between ground and the stoplamp ground terminal.

Is the resistance equal to the specified value?

0 ohms

Go to Step 8

Go to Step 7

7

Repair the ground circuit.

Is the repair complete?

--

System OK

--

8

  1. Disconnect the wiring connector from the brake switch.
  2. Press the brake pedal.
  3. Use an ohmmeter to check continuity between terminals 2 and 4.

Is the resistance equal to the specified value?

0 ohms

Go to Step 10

Go to Step 9

9

Replace the stoplamp switch.

Is the repair complete?

--

System OK

--

10

  1. Disconnect the stoplamp switch electrical connector.
  2. Check the voltage at terminal 4.

Does the voltmeter show the specified value?

11-14 V

Go to Step 12

Go to Step 11

11

Repair the open circuit between the fuse F4 and the brake switch.

Is the repair complete?

--

System OK

--

12

Repair the open circuit between the brake switch and the stoplamps.

Is the repair complete?

--

System OK

--