For 1990-2009 cars

### Power and Ground

The head-up display (HUD) control module receives ignition positive voltage at terminal 11 (CKT 1141, BRN). The HUD control switch receives ignition positive voltage at terminal 6 (CKT 1141, BRN). The HUD control module is grounded at terminal 12 (CKT 251, BLK/WHT). The HUD control switch is grounded at terminal 10 (CKT 251, BLK/WHT).

### HUD Image Dimming with Park Lights ON

The HUD control module receives the dimming input from CKT 32 (YEL) terminal 2.

### HUD Image Intensity Control

The HUD control module monitors CKT 717 (WHT) at terminal 3 in order to determine the image intensity. When the HUD control switch is ON, the DIM to BRIGHT switch varies the voltage at terminal 7 of the HUD control switch. When the HUD control module detects that the park lights are OFF (CKT 32, YEL), the HUD control module uses the input at terminal 3 in order to adjust the image intensity to the desired level. When the HUD control switch is OFF, terminal 7 is connected to ground at terminal 10 (CKT 251, BLK/WHT) of the HUD control switch. When the HUD control module detects a low (ground) condition at terminal 3 (CKT 717, WHT) the HUD image turns OFF.

### HUD Image Position Control

The HUD adjuster motor is connected to the HUD control switch on CKT 621 (YEL) terminal 6 and CKT 620 (BRN) terminal 5. Both circuits are normally grounded within the switch. Pressing the UP or DN button on the switch connects one of the motor circuits (CKT 620 or CKT 621) to ignition voltage. This condition causes the motor to run and moves the HUD display up or down.

### HUD Speedometer

The HUD control module receives the vehicle speed signal (VSS) from the powertrain control module (PCM) on CKT 817 (DK GRN/WHT) terminal 8. When the HUD control module detects a VSS input on CKT 817, the respective vehicle speed is displayed.

### HUD English/Metric Input

The HUD can display the speedometer in either English (MPH) or metric (km/h) units. If the HUD control module detects a high (open) condition at terminal 7, the speedometer is displayed in English units (MPH). On vehicles with RPO Z49, the following actions occur:

• | Terminal 7 is connected to G201 through CKT 1450 (BLK).

• | The HUD control module detects a low (ground) condition.

• | The speedometer is displayed in metric units (km/h).

### LH Turn Signal, RH Turn Signal, and High Beam Indicator Inputs

The HUD control module receives the LH turn signal input on CKT 14 (LT BLU) terminal 5. The HUD control module receives the RH turn signal input on CKT 15 (DK BLU) terminal 10. The high beam indicator signal is applied to the HUD control module on CKT 11 (LT GRN) terminal 9. When the HUD control module detects an ignition voltage input on any circuit, the respective indicator is illuminated.

### CHECK GAUGES and Low Fuel Indicator Inputs

The HUD control module receives the CHECK GAUGES indicator input from the instrument cluster on CKT 1675 (BRN) terminal 6. The HUD control module receives the low fuel indicator input from the instrument cluster on CKT 1194 (DK GRN/WHT) terminal 4. When the HUD control module detects an ignition voltage input on either circuit, the respective indicator is illuminated.