GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

  1. Disconnect the instrument cluster head-up display (HUD) harness connector.
  2. Disconnect the HUD dimmer switch harness connector.
  3. Turn the ignition switch to the RUN position.
  4. Use a J 39200 digital multimeter (DMM) in order to measure the voltage between the instrument cluster HUD dimmer switch harness connector terminal E and ground.

Is any voltage present on CKT 621?

--

Go to Step 3

Go to Step 2

2

Inspect CKT 621 for a short to ground.

Does a short to ground exist in CKT 621?

--

Go to Step 3

Go to Step 4

3

  1. Repair the short to B+ or the short to ground in CKT 621.
  2. Inspect the system.

Is the repair complete?

--

System OK

--

4

Use a J 39200 digital multimeter (DMM) in order to measure the voltage between the instrument cluster HUD dimmer switch harness connector terminal H and ground.

Is any voltage present on CKT 620?

--

Go to Step 6

Go to Step 7

5

Inspect CKT 620 for a short to ground.

Does a short to ground exist in CKT 620?

--

Go to Step 6

Go to Step 7

6

  1. Repair the short to B+ or the short to ground in CKT 620.
  2. Inspect the system.

Is the repair complete?

--

System OK

--

7

Use a J 39200 digital multimeter (DMM) order to measure the resistance between the instrument cluster HUD dimmer switch harness connector terminal G and ground.

Is the measured resistance to ground within the specified value?

0-3 ohms

Go to Step 9

Go to Step 8

8

  1. Repair CKT 1550 for an open or a poor connection between the instrument cluster HUD dimmer switch harness connector and G200.
  2. Inspect the system.

Is the repair complete?

--

System OK

--

9

Use a J 39200 digital multimeter (DMM) in order to measure the voltage between the instrument cluster HUD dimmer switch harness connector terminal A and ground.

Is the measured voltage within the specified value?

9-14 V

Go to Step 11

Go to Step 10

10

  1. Repair the open or the poor connection in CKT 39 between the instrument panel cluster HUD dimmer switch and the fuse block I/P IGN fuse.
  2. Inspect the system.

Is the repair complete?

--

System OK

--

11

  1. Reconnect the instrument cluster HUD dimmer switch harness connector.
  2. Ensure that the instrument cluster HUD harness connector is disconnected.
  3. Turn the ignition switch to the RUN position.
  4. Use a DMM in order to measure the voltage between the instrument cluster HUD harness connector terminal B1 and ground.
  5. Depress the UP button on the instrument cluster HUD dimmer switch.

Is the measured voltage within the specified value?

9-14 V

Go to Step 12

Go to Step 13

12

  1. Use a J 39200 digital multimeter (DMM) in order to measure the voltage between the instrument cluster HUD harness connector terminal B2 and ground.
  2. Press the DOWN button on the instrument cluster HUD dimmer switch.

Is the measured voltage within the specified value?

9-14 V

Go to Step 14

Go to Step 13

13

  1. Replace the instrument cluster HUD dimmer switch. Refer to Head Up Display Switch Replacement .
  2. Inspect the system.

Is the repair complete?

--

System OK

--

14

  1. Replace the instrument cluster HUD display. Refer to Head Up Display Module Replacement .
  2. Inspect the system.

Is the repair complete?

--

System OK

--