GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2005 🢒 Grand Prix 🢒 Body 🢒 Instrument Panel, Gages, and Console 🢒 DTC B3634

Circuit Description

The head-up display (HUD) detects that the HUD dimming signal circuit is low for greater than 15 seconds. The HUD monitors the switch signal circuits in order to perform various functions. The HUD switch contains 3 active low momentary switches and a variable resistor. The HUD detects a switch activation when the signal circuit is active.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B3634 Head Up Display (HUD) Dimming Switch Circuit

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The HUD detects that the HUD dimming signal circuit is low for greater than 60 seconds.

Action Taken When the DTC Sets

The HUD ignores the malfunctioning switch circuit.

Conditions for Clearing the DTC
    • The current DTC clears when fault is no longer present but all history codes remain.
    • The HUD receives a clear code command from the scan tool.

Step

Action

Yes

No

Schematic Reference: Head Up Display Schematics

1

Did you review the operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - Instrument Panel, Gages and Console

2
  1. Turn ON the ignition, with the engine ON.
  2. Adjust the head-up display (HUD) switch to maximum intensity and then to minimum intensity.

Does the HUD dim properly?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3
  1. Turn OFF the ignition.
  2. Disconnect the HUD.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a DMM between the HUD illuminated display signal circuit and ground. Refer to Circuit Testing in Wiring Systems.
  5. Adjust the HUD dimmer switch to maximum intensity and then to minimum intensity.

Does the DMM go from 0-10 ohms?

Go to Step 6

Go to Step 4

4

Test the HUD illuminated display signal circuit for a short to battery voltage or for a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 5

5

Inspect for poor connections at the HUD switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 7

6

Inspect for poor connections at the HUD module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 8

7

Replace the HUD switch. Refer to Head Up Display Switch Replacement .

Did you complete the replacement?

Go to Step 9

--

8

Replace the HUD. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 9

--

9
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

System OK

Go to Step 2