GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2009 🢒 CTS 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC B128D

Diagnostic Instructions
    •  Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    •  Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B128D 01: Video Display Position Signal Short to Battery

DTC B128D 02: Video Display Position Signal Short to Ground

DTC B128D 04: Video Display Position Signal Open Circuit

Circuit/System Description

Pressing the NAV button, located on the Infotainment Faceplate Control Module or faceplate, sends a 5-volt signal on the video display position control circuit to the Display Module Actuator. The 5-volt signal sets the position of the Display Module Actuator commanding the display to the Up position. Pressing the NAV button again removes the signal on the circuit commanding the display to the Down position.

When the display is commanded to the Up position, the motor controller, located in the actuator, sends a 5-volt signal on the video display position signal circuit to the navigation radio. This signal is read by the radio in order to know which graphics to render on the touch-screen display.

Conditions for Running the DTC

The following are conditions that must be present in order for the navigation radio to enable diagnostics:

    • The ignition must be in the RUN or ACC position.
    • The system voltage is at least 9.5 volts and no more than 15.5 volts.

Conditions for Setting the DTC

All the below conditions are present for greater than 250 mS:

    • The navigation radio detects a short to battery on the popup position sense circuit.
    • The navigation radio detects a short to ground on the popup position sense circuit.
    • The navigation radio detects an open on the popup position sense circuit

Action Taken When the DTC Sets

The Display Module Actuator is inoperative.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing
  1. Ignition ON, place the navigation display in the down position.
  2. Ignition OFF, disconnect the X4 harness connector at the radio.
  3. Ignition ON, test for less than 1 volt between signal terminal 13 and ground.
    4. ⇒If greater than specified range, test the signal circuit for a short to voltage. If circuit tests normal, replace the navigation display.
  4. Ignition OFF, test for infinite resistance between the signal terminal 13 and ground.
    5. ⇒If less than specified range, test the signal circuit for a short to ground. If circuit tests normal, replace the navigation display.
  5. Ignition OFF, disconnect the X2 harness connector at the radio/HVAC display.
  6. Test for less than 5 ohms between the signal circuit terminal 13 X4 at the radio and terminal 5 X2 at the navigation display
    7. ⇒If greater than specified value, test the circuit for an open/high resistance.
  7. If the circuit tests normal, replace the radio.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Radio, Video, Audio Disc Player, and Navigation Information Display Replacement
    •  Control Module References for radio replacement, setup, and programming