GM Service Manual Online
For 1990-2009 cars only

Step

Action

Values

Yes

No

1

Check fuses F13 and Ef23.

Is either fuse blown?

--

Step 2

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

  1. Turn the ignition ON.
  2. Check the voltage at fuses F13 and Ef23.

Does the battery voltage available at both fuses F13 and Ef23 equal the specified value?

11-14 V

Step 4

Step 7

4

  1. Turn the hazard switch on.
  2. Remove each of the inoperative lamps from its socket.
  3. Test each lamp socket positive terminal with a voltmeter.

Does the battery voltage pulsing at the turn signal hazard lamp socket positive terminal equal the specified value?

11-14 V

Step 5

Step 9

5

At each bulb socket, use an ohmmeter to check the ground circuit.

Is the resistance equal to the specified value?

0 ohms

Step 6

Step 8

6

Replace any faulty turn signal/hazard bulbs.

Is the repair complete?

--

System OK

--

7

Repair the power supply circuit to fuses.

Is the repair complete?

--

System OK

--

8

Repair the open ground wires.

Is the repair complete?

--

System OK

--

9

  1. Turn on the hazard lamp switch.
  2. Test the blinker unit connector terminal 49a with a voltmeter.

Does the battery voltage pulsing at the blinker unit terminal 49a equal the specified value?

11-14 V

Go to Step 15

Go to Step 10

10

  1. Turn on the hazard lamp switch.
  2. Test the blinker unit connector terminal 49 with a voltmeter.

Does the battery voltage available at the blinker unit terminal 49 equal the specified value?

11-14 V

Go to Step 11

Go to Step 14

11

  1. Disconnect the blinker unit from the connector.
  2. Use an ohmmeter to check between ground and the connector for terminal 31 of the blinker unit.

Is the resistance equal to the specified value?

0 ohms

Go to Step 13

Go to Step 12

12

Repair the blinker unit ground connection.

Is the repair complete?

--

System OK

--

13

Replace the faulty blinker unit.

Is the repair complete?

--

System OK

--

14

  1. Disconnect the hazard lamp switch connector.
  2. Check for voltage at terminal 8.
  3. Turn the ignition ON.
  4. Check for voltage at terminal 10.

Does the battery voltage available at both terminals equal the specified value?

11-14 V

Go to Step 15

 

15

  1. Remove the hazard lamp switch.
  2. Turn the hazard lamp switch off.
  3. Check for continuity between terminals 7 and 10.
  4. Turn the hazard lamp switch on.
  5. Check for continuity between terminals 7 and 8.

Do both tests show the specified value?

0 ohms

Go to Step 18

Go to Step 17

16

  1. Remove the hazard lamp switch.
  2. Turn the hazard lamp switch on.
  3. Use an ohmmeter to check for continuity between terminals 5, 6, and 9.

Does the continuity between terminals 5, 6, and 9 equal the specified value?

0 ohms

Go to Step 19

Go to Step 17

17

Replace the faulty hazard lamp switch.

Is the repair complete?

--

System OK

--

18

Repair the open circuit between the hazard lamp switch terminal 7 and the blinker unit terminal 49.

Is the repair complete?

--

System OK

--

19

Repair the open circuit between the hazard lamp switch and the fuses F13 and Ef23.

Is the repair complete?

--

System OK

--