GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

  1. Turn the ignition switch to RUN.
  2. Measure the voltage from HUD switch connector terminal 8 to ground (backprobe).
  3. Move the HUD dim switch from the minimum position to the maximum position.

Does the voltage vary within the specified range?

0-15 V

Go to Step 7

Go to Step 2

2

  1. Turn the ignition switch OFF.
  2. Test CKT 622 for a short to ground.

Does a short to ground exist in CKT 622?

--

Go to Step 3

Go to Step 4

3

Repair the short to ground in CKT 622.

Is the repair complete?

--

Go to Diagnostic System Check - Instrument Cluster

--

4

Inspect for loose or corroded terminals at the HUD switch connector.

Do any loose or corroded terminals exist at the HUD switch connector?

--

Go to Step 5

Go to Step 6

5

Repair the loose or corroded terminals at the HUD switch connector.

Are the repairs complete?

--

Go to Diagnostic System Check - Instrument Cluster

--

6

Replace the HUD switch.

Is the repair complete?

--

Go to Diagnostic System Check - Instrument Cluster

--

7

  1. Turn the ignition switch to OFF.
  2. Disconnect the HUD module connector.
  3. Turn the ignition switch to RUN.
  4. Measure the voltage from HUD module connector terminal B8 to ground.
  5. Move the HUD dim switch from the minimum position to the maximum position.

Does the voltage vary within the specified range?

5-12 V

Go to Step 10

Go to Step 8

8

Test CKT 622 for an open.

Does an open exist in CKT 622?

--

Go to Step 9

Go to Step 10

9

Repair the open in CKT 622.

Is the repair complete?

--

Go to Diagnostic System Check - Instrument Cluster

--

10

Inspect for loose or corroded terminals at the HUD module connector.

Do any loose or corroded terminals exist at the HUD module connector?

--

Go to Step 11

Go to Step 12

11

Repair the loose or corroded terminals at the HUD module connector.

Are the repairs complete?

--

Go to Diagnostic System Check - Instrument Cluster

--

12

Replace the HUD module.

Is the repair complete?

--

Go to Diagnostic System Check - Instrument Cluster

--