Cruise Control System Cadillac DTS I

Fastener Tightening Specifications

Scheme 1

Scheme 2

Scheme 3

DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Diagnostic Starting Point - Cruise Control

Begin the system diagnosis with the Diagnostic System Check - Vehicle . The Diagnostic System Check will provide the following information

1. The identification of the control modules which command the system
2. The ability of the control modules to communicate through the serial data circuit
3. The identification of any stored DTCs and their status

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit/System Description

The cruise control switch is an input to the body control module (BCM). The BCM monitors the cruise control switch signal circuit in order to detect when the driver has requested to perform a cruise control function. The BCM detects a specific voltage signal on the cruise control switch signal circuit when a switch is applied.

Conditions for Running the DTC

1. The ignition is ON.
2. The cruise switch is ON.

DTC B3794 08

The BCM detects an invalid voltage signal on the cruise control switch signal circuit is present for 0.5 second.

DTC B3794 61

The BCM detects an valid voltage signal on the cruise control switch signal circuit is present for greater 60 seconds.

Action Taken When the DTC Sets

1. The BCM stores the DTC information into memory when the diagnostic runs and fails.
2. The malfunction indicator lamp (MIL) will not illuminate.
3. The Cruise Control System is disabled.

Conditions for Clearing the DTC

1. The DTC becomes history when the conditions for setting the DTC are no longer present.
2. The history DTC clears after 100 malfunction-free warm-up cycles.

Reference Information

Schematic Reference

1. «Cruise Control Schematics»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system)
2. «Steering Wheel Secondary/Configurable Control Schematics»(/cadillac/dts/i-2005-2011/remont/memory-modules/#configurable-customer-control-system)

Connector End View Reference

Component Connector End Views

Description and Operation

Cruise Control Description and Operation (Conventional Cruise Control) or Cruise Control Description and Operation (Adaptive Cruise Control)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, observe the scan tool Cruise Control Switch parameter in the BCM. While pressing each of the cruise control switches, the scan tool display should change to display the current switch being actuated.

Circuit/System Testing

1. With the ignition OFF, remove the inflatable restraint steering wheel module. Refer to «Inflatable Restraint Steering Wheel Module Replacement»(/cadillac/dts/i-2005-2011/remont/airbag/#supplemental-inflatable-restraint-system) .
2. Disconnect the harness connector at the cruise control switch.
3. Ignition ON, test for greater than 10 volts between the supply circuit terminal 1 and ground. If less than the specified range, test the supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Verify the scan tool Cruise Control Switch parameter is OFF. If not the specified value, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the BCM.
5. Ignition OFF, connect the harness connector at the cruise control switch.
6. Ignition ON, cruise control switch ON, observe the scan tool Cruise Control Switch parameter. The parameter should display ON. If not the specified value, test the signal circuit terminal 3 for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the cruise control switch.
7. Observe the scan tool Cruise Control Switch parameter while pressing the RES + portion of the cruise control switch. The parameter should display Resume. If not the specified value, test or replace the cruise control switch.
8. Observe the scan tool Cruise Control Switch parameter while pressing the SET - portion of the cruise control switch. The parameter should display Set. If not the specified value, test or replace the cruise control switch.
9. Observe the scan tool Cruise Control Switch parameter while pressing the Cancel portion of the cruise control switch. The parameter should display Cancel. If not the specified value, test or replace the cruise control switch.
10. If all circuits and the component test normal, replace the BCM.

Component Testing

1. Ignition OFF, remove the inflatable restraint steering wheel module. Refer to «Inflatable Restraint Steering Wheel Module Replacement»(/cadillac/dts/i-2005-2011/remont/airbag/#supplemental-inflatable-restraint-system) .
2. Remove the steering wheel cruise control switch. Refer to «Steering Wheel Control Switch Assembly Replacement»(/cadillac/dts/i-2005-2011/remont/memory-modules/#configurable-customer-control-system) .
3. Connect a DMM between terminals 1 and 3 of the cruise control switch. Cruise control ON/OFF switch ON, measure the resistance while individually activating and holding each cruise control function switch and compare the resistance reading to the values in the table for the appropriate switch. If any of the resistance measurements for the individual switches are not within the listed resistance values, replace the cruise control switch assembly.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Steering Wheel Control Switch Assembly Replacement»(/cadillac/dts/i-2005-2011/remont/memory-modules/#configurable-customer-control-system)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The forward looking sensor (FLS) radar is a part of the distance sensing cruise control (DSCC) module but has the exclusive function of detecting, tracking and classifying targets within its specified field of view. The FLS radars ability to detect and react to objects of interest in its detection zone is critical to the proper operation of the adaptive cruise control (ACC) system. When the DSCC module detects that the FLS radar is out of alignment, a DTC C1002 sets.

1. The ignition is ON.
2. The cruise switch is ON.

Conditions for Setting the DTC

1. The DSCC module detects there is 3.9 degrees of skew or error of the FLS.
2. The vehicle speed is at or greater than 40.2 km/h (25 mph).

1. Loss of Adaptive Cruise Control (ACC) function.
2. Service Radar Cruise message is displayed in the driver information center (DIC).

1. The DTC becomes history when the conditions for setting the DTC are no longer present.
2. The history DTC clears after 100 malfunction-free warm-up cycles.
3. The DSCC module receives a clear code command from the scan tool.

Diagnostic Aids

An FLS radar out of alignment condition may be as a result of tampering with the DSCC module mounting structures/brackets or the adjuster settings. An out of alignment condition may also be a result of damage to the front section of the ACC equipped vehicle or the DSCC module.

Schematic Reference

Cruise Control Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cruise Control Description and Operation (Conventional Cruise Control) or Cruise Control Description and Operation (Adaptive Cruise Control)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

BO-047670 Adaptive Cruise Control (ACC) Radar Alignment Tool. See Special Tools .

1. Align the FLS radar using the alignment tool. Refer to «Distance Sensing Cruise Control Aiming»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system) . If alignment cannot be achieved within the limits of the available adjustment, inspect the mounting structures and brackets for damage or tampering and repair as necessary to achieve proper alignment.
2. Road test the vehicle and ensure the ACC system functions normally and DTC C1002 does not set as current. Refer to «Cruise Control Description and Operation (Conventional Cruise Control)»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system__cruise-control-description-operation-conventional) or «Cruise Control Description and Operation (Adaptive Cruise Control)»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system) . If DTC C1002 resets as current, replace the DSCC module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for DSCC module replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The stop lamp switch signal circuit is a direct hardwire input from the body control module (BCM) to the engine control module (ECM), powertrain control module (PCM), transmission control module (TCM) and throttle actuator control (TAC) module (as equipped). The modules monitor the stop lamp switch signal circuit to detect when the brake pedal has been applied. The BCM monitors the brake apply sensor signal circuit to determine when the brake pedal is applied. When the brake pedal is applied, the BCM sends a serial data message to the modules and also a voltage signal on the stop lamp switch signal circuit indicating that the brake pedal has been applied.

1. The ignition is ON.
2. The engine is running.
3. Battery voltage is greater than 11.5 volts.

P0572

The ECM/PCM detects a low voltage signal on the stop lamp switch signal circuit when the serial data message from the BCM indicates the brakes are applied.

P0573

The ECM/PCM detects a high voltage signal on the stop lamp switch signal circuit when the serial data message from the BCM indicates the brakes are not applied.

1. The ECM/PCM stores the DTC to memory.
2. The ECM/PCM will record the operating conditions at the time the diagnostic failed. The ECM/PCM stores this information in Failure Records.
3. The cruise control system becomes inoperative.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 40 malfunction-free ignition cycles have occurred.

Schematic Reference

1. «Exterior Lights Schematics»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Cruise Control Schematics»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system)

Connector End View Reference

Component Connector End Views

Description and Operation

Cruise Control Description and Operation (Conventional Cruise Control) or Cruise Control Description and Operation (Adaptive Cruise Control)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition OFF, disconnect the harness connectors at the control modules for the appropriate engine RPO listed below. PCM X1 and TAC module (with L26) ECM X1 and TCM (with LD8 or L37)
2. Connect a test lamp between the appropriate signal circuit terminal listed below and ground. TAC terminal 6 (with L26) TCM terminal 42 (with LD8 or L37)
3. Ignition ON, press and release the brake pedal. Verify the test lamp turns ON and OFF when pressing and releasing the brake pedal. If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Ignition OFF, connect the harness connector at the TAC module (with L26) or the TCM (with LD8 or L37).
5. Connect a test lamp between the appropriate signal circuit terminal listed below and ground. PCM terminal 32 X1 (with L26) ECM terminal 77 X1 (with LD8 or L37)
6. Ignition ON, press and release the brake pedal. Verify the test lamp turns ON and OFF when pressing and releasing the brake pedal. If the test lamp is always OFF, test the signal circuit for an open/high resistance. If the circuit test normal, replace the appropriate TAC module (with L26) or the TCM (with LD8 or L37).
7. If all circuit tests normal, replace the appropriate PCM (with L26) or the ECM (with LD8 or L37).

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM, PCM, TAC or TCM module replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

When a cruise control function switch is activated, the body control module (BCM) detects a predetermined voltage signal. The BCM sends a serial data message to the engine control module (ECM) indicating the function that has been requested.

The ignition is ON.

1. The ECM receives an invalid cruise control switch status serial data message from the BCM.
2. This diagnostic runs continuously.

1. The Cruise Control System is disabled.
2. The ECM stores the DTC information into memory when the diagnostic runs and fails.
3. The malfunction indicator lamp (MIL) will not illuminate.
4. The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.

1. The DTC becomes history when the conditions for setting the DTC are no longer present.
2. The history DTC clears after 40 consecutive warm-up cycles.

Schematic Reference

Cruise Control Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cruise Control Description and Operation (Conventional Cruise Control) or Cruise Control Description and Operation (Adaptive Cruise Control)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Verify that B3794 is not set as current. If B3794 is set as current, refer to «DTC B3794»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system) .
2. Road test the vehicle and attempt to engage cruise. Verify that cruise control engages properly and that DTC P0575 is not set. If the cruise control system does not operate properly and DTC P0575 is not set, refer to «Cruise Control Malfunction»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system) .

1. If DTC P0575 sets as current, replace the BCM. Clear the DTC and road test the vehicle and attempt to engage cruise. If DTC P0575 resets as current, replace the ECM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM or ECM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The body control module (BCM) monitors the brake pedal position sensor. When the brake pedal is applied, the BCM detects a predetermined voltage signal. The BCM sends a serial data message to the engine control module (ECM)/powertrain control module (PCM) indicating the status of the stop lamps.

The engine is ON.

1. The ECM/PCM receives an invalid brake pedal status serial data message from the BCM.
2. This diagnostic runs continuously.

1. The Cruise Control System is disabled.
2. The ECM/PCM stores the DTC information into memory when this diagnostic runs and fails.
3. The malfunction indicator lamp (MIL) will not illuminate.
4. The ECM/PCM records the operating conditions at the time the diagnostic fails. The ECM/PCM stores this information in the Failure Records.

1. A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
2. A history DTC clears after 40 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic.
3. A clear code command is received from a scan tool.

Schematic Reference

Cruise Control Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

1. «Cruise Control Description and Operation (Conventional Cruise Control)»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system__cruise-control-description-operation-conventional) or «Cruise Control Description and Operation (Adaptive Cruise Control)»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system)
2. «Exterior Lighting Systems Description and Operation»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Repair any brake system related DTCs before performing this diagnostic.
2. Road test the vehicle. Verify that DTC P0572 or P0573 are not set as current. If either DTC is set as current, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-trouble-code-dtc-list) .
3. Verify that DTC P0703 is not set. If DTC P0703 is set as current, replace the BCM. Clear the DTC and road test the vehicle. If DTC P0703 resets as current, replace the ECM/PCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Brake Pedal Position Sensor Replacement»(/cadillac/dts/i-2005-2011/remont/exterior-lights/#lighting-systems)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM, ECM, or PCM replacement, setup and programming

Symptoms - Cruise Control

1. Before using the symptom diagnostic table, perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) , in order to verify the following conditions: There are no DTCs set. The module can communicate via the serial data link.
2. Review the system operation in order to understand the system functions. Refer to «Cruise Control Description and Operation (Conventional Cruise Control)»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system__cruise-control-description-operation-conventional) or «Cruise Control Description and Operation (Adaptive Cruise Control)»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system) .

Visual/Physical Inspection

1. Inspect for aftermarket devices which can affect the operation of the cruise control system. Refer to «Checking Aftermarket Accessories»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__checking-aftermarket-accessories) .
2. Inspect the accessible system components or the visible system components for obvious damage or for obvious conditions which can cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Cruise Control Malfunction»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system)
2. «Cruise Control Indicator Malfunction (Switch Indicator Malfunction)»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system) or «Cruise Control Indicator Malfunction (IPC Indicator Malfunction)»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system)

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The cruise control switch contains an LED that illuminates to indicate the cruise control system has been switched ON. Voltage is applied through the ON/OFF switch to the LED when the switch is pressed. The BCM provides the ground path for the LED through a dedicated dimming control circuit. Pressing the switch again opens the switch and the lamp turns OFF.

1. This diagnostic assumes the cruise control system is operating properly and no DTCs are set. If the cruise control system is malfunctioning, refer to «Cruise Control Malfunction»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system) .
2. If any DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-trouble-code-dtc-list) .

Schematic Reference

Cruise Control Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Engine ON, press and release the cruise control ON/OFF switch while observing the Cruise On/Off Switch parameter in the ECM data list with a scan tool. The parameter should change and the indicator lamp should turn ON or OFF accordingly each time the switch is actuated.

Disable the inflatable restraint steering wheel module when performing this diagnostic. Refer to SIR Disabling and Enabling .

1. Ignition ON, with a scan tool observe the Cruise On/Off Switch parameter. Verify the parameter changes each time the switch is actuated. If the parameter reads ON at all times, replace the cruise control switch.
2. Ignition OFF, remove the inflatable restraint steering wheel module. Refer to «Inflatable Restraint Steering Wheel Module Replacement»(/cadillac/dts/i-2005-2011/remont/airbag/#supplemental-inflatable-restraint-system) .
3. Disconnect the harness connector at the cruise control switch assembly.
4. Ignition ON, test for 0 volts between the cruise control harness connector terminal 9 and ground. If voltage is present, test the circuit for a short to voltage.
5. Ignition OFF, disconnect the X3 connector at the BCM.
6. Test for less than 1.0 ohm between the cruise control harness connector terminal 9 and the BCM connector X3 terminal 22. If greater than the specified value, test the circuit for an open or high resistance.
7. Test for infinite resistance between the cruise control harness connector terminal 9 and ground. If resistance is measured, test the circuit for a short to ground.
8. If all circuits test normal, test the component. If the circuits and component tests are normal, replace the BCM.

Disable the inflatable restraint steering wheel module when performing this diagnostic. Refer to SIR Disabling and Enabling .

1. Ignition OFF, remove the inflatable restraint steering wheel module. Refer to «Inflatable Restraint Steering Wheel Module Replacement»(/cadillac/dts/i-2005-2011/remont/airbag/#supplemental-inflatable-restraint-system) .
2. Remove the steering wheel cruise control switch. Refer to «Steering Wheel Control Switch Assembly Replacement»(/cadillac/dts/i-2005-2011/remont/memory-modules/#configurable-customer-control-system) .
3. Turn the cruise control switch ON. Connect a DMM positive lead to terminal 1 and the negative lead to terminal 9 of the cruise control switch and measure the resistance. Verify the meter reading indicates continuity. If the reading indicates and open circuit, replace the cruise control switch assembly.
4. Connect the DMM positive lead to terminal 9 and the negative lead to terminal 1 of the cruise control switch and measure the resistance. Verify the meter reading indicates an open circuit. If the reading is not as specified, replace the cruise control switch assembly.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Steering Wheel Control Switch Assembly Replacement»(/cadillac/dts/i-2005-2011/remont/memory-modules/#configurable-customer-control-system)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The instrument panel cluster (IPC) illuminates the cruise control engaged indicator based on serial data messages received from the engine control module (ECM) or the powertrain control module (PCM). The indicator is commanded ON when the cruise control system is controlling vehicle speed, and turned OFF with the system disengaged.

1. This diagnostic assumes the cruise control system is functioning normally and there are no DTCs set. If the cruise control system is malfunctioning, refer to «Cruise Control Malfunction»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system) .
2. If any DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-trouble-code-dtc-list) .

Schematic Reference

1. «Cruise Control Schematics»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system)
2. «Instrument Cluster Schematics»(/cadillac/dts/i-2005-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gages)

Connector End View Reference

Component Connector End Views

Description and Operation

1. «Cruise Control Description and Operation (Conventional Cruise Control)»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system__cruise-control-description-operation-conventional) or «Cruise Control Description and Operation (Adaptive Cruise Control)»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system)
2. «Indicator/Warning Message Description and Operation»(/cadillac/dts/i-2005-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gages__indicatorwarning-message-description-operation)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, perform the IPC display test using a scan tool. Verify the indicator illuminates and turns OFF.

1. If the indicator does not operate as expected during this test, replace the IPC.
2. If the indicator functions normally during this test, replace the ECM/PCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM, PCM or IPC replacement, setup and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-system-check-vehicle) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/dts/i-2005-2011/remont/oem-general-information/#vehicle-diagnostic-information__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The cruise control switch is an input to the body control module (BCM). The BCM monitors the cruise control switch signal circuit in order to detect when the driver has requested to perform a cruise control function. The BCM detects a specific voltage signal on the cruise control switch signal circuit when a switch is applied.

Conditions for Enabling Cruise Control

1. The vehicle speed is greater than 40 km/h (25 mph).
2. The vehicle is not in PARK, REVERSE, NEUTRAL, or 1st gear.
3. The system voltage is within 9-16 volts.
4. The park brake or brakes are not applied.

Schematic Reference

1. «Cruise Control Schematics»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system)
2. «Steering Wheel Secondary/Configurable Control Schematics»(/cadillac/dts/i-2005-2011/remont/memory-modules/#configurable-customer-control-system)

Connector End View Reference

Component Connector End Views

Description and Operation

Cruise Control Description and Operation (Conventional Cruise Control) or Cruise Control Description and Operation (Adaptive Cruise Control)

Electrical Information Reference

1. «Circuit Testing»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-poor)
4. «Wiring Repairs»(/cadillac/dts/i-2005-2011/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, cruise on/off switch ON. With a scan tool, observe the scan tool Cruise Control Switch parameter in the BCM. While pressing each of the cruise control switches, the scan tool display should change to display the current switch being actuated. Road test the vehicle to ensure the cruise control system functions as described in Cruise Control Description and Operation (Conventional Cruise Control) or Cruise Control Description and Operation (Adaptive Cruise Control) .

1. With the ignition OFF, remove the inflatable restraint steering wheel module. Refer to «Inflatable Restraint Steering Wheel Module Replacement»(/cadillac/dts/i-2005-2011/remont/airbag/#supplemental-inflatable-restraint-system) .
2. Disconnect the harness connector at the cruise control switch.
3. Ignition ON, test for greater than 10 volts between the supply circuit terminal 1 and ground. If less than the specified range, test the supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Verify the scan tool Cruise Control Switch parameter is OFF. If not the specified value, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the BCM.
5. Ignition OFF, connect the harness connector at the cruise control switch.
6. Ignition ON, cruise control switch ON, observe the scan tool Cruise Control Switch parameter. The parameter should display ON. If not the specified value, test the signal circuit terminal 3 for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the cruise control switch.
7. Observe the scan tool Cruise Control Switch parameter while pressing the RES + portion of the cruise control switch. The parameter should display Resume. If not the specified value, test or replace the cruise control switch.
8. Observe the scan tool Cruise Control Switch parameter while pressing the SET - portion of the cruise control switch. The parameter should display Set. If not the specified value, test or replace the cruise control switch.
9. Observe the scan tool Cruise Control Switch parameter while pressing the Cancel portion of the cruise control switch. The parameter should display Cancel. If not the specified value, test or replace the cruise control switch.
10. If all circuits and the component test normal, replace the BCM.

1. Ignition OFF, remove the inflatable restraint steering wheel module. Refer to «Inflatable Restraint Steering Wheel Module Replacement»(/cadillac/dts/i-2005-2011/remont/airbag/#supplemental-inflatable-restraint-system) .
2. Remove the steering wheel cruise control switch. Refer to «Steering Wheel Control Switch Assembly Replacement»(/cadillac/dts/i-2005-2011/remont/memory-modules/#configurable-customer-control-system) .
3. Connect a DMM between terminals 1 and 3 of the cruise control switch. Cruise control ON/OFF switch ON, measure the resistance while individually activating and holding each cruise control function switch and compare the resistance reading to the values in the table for the appropriate switch. If any of the resistance measurements for the individual switches are not within the listed resistance values, replace the cruise control switch assembly.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Steering Wheel Control Switch Assembly Replacement»(/cadillac/dts/i-2005-2011/remont/memory-modules/#configurable-customer-control-system)
2. «Control Module References»(/cadillac/dts/i-2005-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

Scheme 4

Tools Required

BO-047670 Adaptive Cruise Control (ACC) Radar Alignment Tool. See Special Tools .

DSCC Aiming Set Up Procedure

1. Prior to aiming the distance sensing cruise control (DSCC), the following steps must be taken: Align the wheels, if necessary, before aiming the DSCC. Inflate the tires to the proper pressure. The vehicle must have a full tank of gas. If any service has been performed on the vehicle, make sure that all of the components are back in their original place. Remove any snow, ice or mud from the vehicle. Stop all other work on the vehicle. Do not load any cargo in the vehicle. Remove the front bumper fascia grille. Refer to «Fascia Grille Replacement»(/cadillac/dts/i-2005-2011/remont/exteriorinterior-trim/#exterior-trim) .
2. The area needed for aiming of the DSCC will consist of a vertical wall and a level surface 8 m (26 ft 2 in) in length (a), 3 m (9 ft 9 in) in width (b), and 2 m (6 ft 6 in) in height (c).
3. Place the vehicle so the DSCC module is approximately 6 m (19 ft 7 in) from the vertical wall (a), rock the vehicle to stabilize the suspension, and center the steering wheel.
4. Mark two points (a, b) on the left side of the rear window glass from the roof sheet metal using an erasable marker or chalk. Measure the same distances on the opposite side from the roof sheet metal and draw two lines across the rear window glass connecting points a and b.
5. Measure the center points of lines a and b and draw a new, dashed line vertically through the center of the rear glass (c, d).
6. Repeat this procedure on the front glass to find the center point of the windshield.
7. Hold BO-047670 steady at the rear glass and turn the tool on. See «Special Tools»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system) . Shine the laser beam through the vertical lines drawn on the front and rear glass to the wall.
8. Have a partner mark the wall where the laser beam appears. This is the true center line of the vehicle.
9. Using the floor as a reference, measure the height from the floor to the center point of the radar face.
10. On the vertical wall measure the same distance measured in step 9 from the floor up the line created in step 8 and make cross hairs.

DSCC Aiming Procedure

1. Turn the ignition completely off.
2. Install BO-047670 to the front of the DSCC module (3). See «Special Tools»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system) .
3. Check that the spring tension rods are installed in the proper position and that all three legs on BO-047670 are touching the ACC housing before continuing. See «Special Tools»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system) .
4. Turn the laser beam on.
5. Adjust the horizontal aim screw (2) and vertical aim screw (4) of the DSCC module until the laser beam is in the center of the cross hairs on the vertical wall.
6. Turn off the laser beam and remove BO-047670 . See «Special Tools»(/cadillac/dts/i-2005-2011/remont/cruise-control-systems/#cruise-control-system) .
7. Install a scan tool.
8. Turn ON the ignition, with the engine OFF.
9. With the scan tool, perform the Factory Reset for the DSCC module in the Body and Accessories, Cruise Control Special Functions.
10. Install the grille and front compartment sight shields. Refer to «Fascia Grille Replacement»(/cadillac/dts/i-2005-2011/remont/exteriorinterior-trim/#exterior-trim) .

Distance Sensing Cruise Control Maintenance

1. Remove the distance sensing cruise control (DSCC) module cover from the fascia (6) grille.
2. Clean the surfaces of the inner and outer DSCC module cover with a 50/50 mixture of isopropyl alcohol and water by volume on a dampened lint free cloth.
3. With the same solution, clean the outer surface of the DSCC module (3).
4. Install the DSCC module cover to the fascia (6) grille.

Cruise Control Description & Operation (Conventional Cruise Control)

Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions at speeds above 40 km/h (25 mph). Steep grades may cause variations in the selected vehicle speeds.

The following are the main components of the Cruise Control System

1. The accelerator pedal
2. The brake pedal position (BPP) sensor
3. The body control module (BCM)
4. The cruise control switches
5. The engine control module (ECM)
6. The throttle actuator control (TAC) motor
7. The vehicle speed sensor (VSS)

Cruise Control Engaged

The Cruise Control System will engage and adjust vehicle speeds, based on the activation of the following cruise control switches, which are located on the steering wheel

1. The on/off switch
2. The + RES switch
3. The - SET switch

The body control module (BCM) monitors the signal circuit of the cruise control switches. The BCM relays the cruise control switch status to the engine control module (ECM) via the GMLAN serial data circuit. The ECM uses the status of the cruise control switch to determine when to capture and maintain the vehicle speed. The ECM monitors the vehicle speed signal circuit in order to determine the desired vehicle speed. The ECM uses the throttle actuator control (TAC) motor in order to maintain the vehicle speed. For further information on the TAC System, refer to Throttle Actuator Control (TAC) System Description .

Voltage is supplied to the cruise control switch from the steering wheel control switch reference voltage circuit supplied by the BCM. The cruise control switches are arranged in a resistive ladder design, with each cruise control function switch having a different resistance value. The BCM detects a specific voltage value that is associated with the cruise control function switch being activated. When the normally open cruise control On/Off switch is turned ON, the switch closes and the BCM supplies a ground to the cruise control switch ON indicator circuit as it becomes illuminated. The BCM sends a GMLAN serial data message to the ECM indicating that the On/Off switch is active. Similarly, when the normally open + RES switch or the normally open - SET switch are pressed, the switch closes and the BCM detects the predetermined voltage signal on the - SET switch and the + RES switch signal circuit. The BCM sends a GMLAN serial data message to the ECM indicating that the + RES switch or the - SET switch is active. To engage the Cruise Control System, ensure that the vehicle speed is above 40.2 km/h (25 mph), and then turn the On/Off switch ON and momentarily press the - SET switch. The ECM will engage the Cruise Control System and record the vehicle speed. The ECM sends a GMLAN serial data message to the driver information center (DIC) in order to illuminate the CRUISE SET TO ### message. The ECM sends a GMLAN serial data message to the instrument panel cluster (IPC) in order to illuminate the Cruise Engaged indicator in the IPC. The - SET switch and the + RES switch will remain inactive when the BCM has not received the predetermined voltage signal from the On/Off switch. Pressing the accelerator pedal, while the Cruise Control System is engaged, will allow the driver to override the Cruise Control System in order to accelerate the vehicle beyond the current set vehicle speed. When the accelerator pedal is released, the vehicle will decelerate and resume the current set vehicle speed. The driver can also override the current set vehicle speed via the - SET switch and the + RES switch. When the Cruise Control System is engaged, pressing and holding the - SET switch will allow the vehicle to decelerate from the current set vehicle speed without deactivating the Cruise Control System. When the - SET switch is released, the ECM will record the vehicle speed and maintain the vehicle speed as the new set vehicle speed. When the Cruise Control System is engaged, momentarily pressing - SET switch will allow the vehicle to decelerate at 1.6 km/h (1 mph) increments for each time that the - SET switch is momentarily pressed, with a minimum vehicle speed of 37 km/h (23 mph). Pressing and holding the + RES switch, when the Cruise Control System is engaged, will allow the vehicle to accelerate to a greater vehicle speed than the current set vehicle speed. When the + RES switch is released, the ECM will record the vehicle speed and maintain the vehicle speed as the new set vehicle speed. When the Cruise Control System is engaged, momentarily pressing the + RES switch will allow the vehicle to accelerate at 1.6 km/h (1 mph) increments for each time that the + RES switch is momentarily pressed, with the maximum acceleration total of 16 km/h (10 mph) over the current set vehicle speed. Momentarily activating the + RES switch will recall the previous vehicle speed, after the Cruise Control System is disengaged by pressing the brake pedal or by activating the CANCEL switch.

Cruise Control Disengaged

The engine control module (ECM) disengages the cruise control operation based on the signals from the following switches

1. The brake pedal position (BPP) sensor
2. The cruise control On/Off switch
3. The cruise control cancel switch

The body control module (BCM) determines when the cruise control cancel switch is activated. When the normally open cancel switch is closed, the BCM detects the predetermined voltage signal on the cruise control function switch circuit. The BCM sends a GMLAN serial data message to the ECM in order to disengage the cruise control system.

The BPP sensor is mounted on the brake pedal bracket. Pressing the brake pedal while the cruise control is engaged will disengage the Cruise Control system. The BCM monitors the BPP sensor signal circuit as the voltage signal increases, while the pedal reaches the fully applied position. The BCM sends a GMLAN serial data message to the ECM indicating the position of the brake pedal. For more information on the BPP sensor, refer to Exterior Lighting Systems Description and Operation and to Brake Pedal Position Sensor Calibration .

The Cruise Control System will also disengage when one of the following conditions exist

1. The cruise control On/Off switch is switched OFF.
2. The ECM detects that a drive override function has been active for approximately 60 seconds.

When the Cruise Control System has been disengaged, the ECM sends a GMLAN serial data message to the instrument panel cluster (IPC) in order to turn OFF the Cruise Engaged indicator, and to the drive information center (DIC) in order to turn OFF the CRUISE SET TO ### message. The vehicle speed stored in the memory of the ECM will be erased when the cruise control On/Off button is turned OFF, or the ignition switch is turned OFF.

Cruise Control Inhibited

The engine control module (ECM) inhibits the cruise control operation when any of the following conditions exist

1. The ECM has not detected a brake pedal activation from the body control module (BCM).
2. A Cruise Control System DTC has been set.
3. The vehicle speed is less than 40.2 km/h (25 mph).
4. The vehicle is in PARK, REVERSE, NEUTRAL, or 1st gear.
5. The engine RPM is too low.
6. The engine RPM is too high.
7. The vehicle speed is too high.
8. The system voltage is not between 9-16 volts.
9. The Antilock Brake System (ABS)/Traction Control System (TCS) is active for more than 2 seconds.

Adaptive Cruise Control (ACC)

The Adaptive Cruise Control System (ACC) is an enhanced Cruise Control System with the ability to sense and react to forward traffic. Compared to the common Cruise Control System found on many vehicles, the main functional enhancement of the ACC System is the ability to detect the presence of a vehicle in the path of the ACC vehicle. The ACC retains the existing cruise control feature that controls the vehicle speed to the driver selected speed. However, ACC allows a driver to set and maintain a following distance to the preceding nearest vehicle in the ACC vehicle path. The distance sensing cruise control (DSCC) module calculates a follow speed limit to ensure an acceptable distance is maintained to the preceding vehicle in front, should one be present. The ACC System automatically adjusts the speed of an ACC vehicle when the vehicle comes up behind a slower travelling vehicle in front. The ACC System applies limited automatic braking and throttle control without driver input when necessary to maintain the set following distance of the ACC vehicle. The preceding vehicle's speed and acceleration along with the ACC vehicle speed and acceleration and the distance between the 2 vehicles are factors used by the DSCC module to determine the ACC follow speed limit. The ACC vehicle speeds up to the original driver selected set speed when the pathway becomes clear without driver input.

Adaptive Cruise Control (ACC) System Description

The Adaptive Cruise Control (ACC) System depends on various modules on the vehicle to function and each module performs a function that is critical to the proper operation of the ACC System. ACC will not operate if any components fail. Communication between modules is via the high-speed GMLAN serial data circuit. The instrument panel module (IPM) provides a translating gateway function for the GMLAN serial data links. The GMLAN utilizes the controller area network (CAN) communications protocol. The following is a functional description of the distance sensing cruise control (DSCC) module and the other associated components

Distance Sensing Cruise Control (DSCC) Module

The DSCC module contains the radar and the DSCC controller. The DSCC module utilizes the radar to identify and classify objects in the road environment. The radar scans the road environment to detect targets within its specified field of view. The DSCC controller then makes throttle and/or brake commands to the engine control module (ECM) and electronic brake control module (EBCM) via the GMLAN serial data circuit in order to control the vehicle acceleration/deceleration based on the data from the radar. The ECM and EBCM provide throttle control and automatic braking needed for proper cruise speed adjustment. An internal yaw rate sensor is used by the DSCC module to determine the predicted path of the ACC vehicle. The main power feed for the DSCC module is the battery and this signal is always at battery potential. However, the ACC System only activates when the ignition 1 input is active and in the RUN position. The ignition 1 voltage signal to the DSCC module has to be 9.2 volts or more to be considered active by the DSCC module. When the ignition 1 signal is not active, all ACC functions are disabled. The following is a list of the DSCC module functions

1. The radar processes the road environment to get data concerning any vehicle ahead of the ACC vehicle. Detection, parameter estimation, tracking, object classification and diagnostics are the primary radar functions. When an object is detected, the DSCC controller calculates the object range, range rate, acceleration and azimuth angle parameters.
2. The DSCC module performs ACC state processing automatically-distance control or speed control. The ACC System operates in 2 possible states-Cruise or Follow. The normal operating state is Cruise, whereby the vehicle speed is controlled to match the driver selected set speed. When a preceding forward target is identified by the radar, the ACC System will automatically transition into the follow speed state to provide proper lane spacing behind the target vehicle in front. The preceding vehicle's speed and acceleration, with the ACC vehicle speed, acceleration and distance between the two vehicles will be used to determine the ACC follow speed limit. The ACC follow speed limit will ensure that an acceptable distance is maintained to the preceding vehicle.
3. The DSCC module determines the follow speed limit for throttle control by the ECM.
4. The DSCC module arbitrates the ACC System brake and throttle control between the EBCM and the ECM.
5. The DSCC module requests brake light activation during automatic braking.
6. The DSCC module provides operational feedback to the vehicle driver. The DSCC module sends signals for telltales and messages to be displayed on the driver information center (DIC) via the IPM. The DSCC module will provide audible feedback to the driver via the IPM and the radio amplifier as well.

Instrument Panel Module (IPM)

The following are the ACC System functions provided by the IPM

1. The IPM provides a translating gateway for the high speed GMLAN serial data circuit.
2. The IPM reads all cruise control switches and the gap switch. The DSCC module monitors a variety of user operated switches from the IPM switch status information sent via the GMLAN serial data circuit.
3. The IPM illuminates the brake light based on a GMLAN message from the DSCC module during automatic braking.
4. The IPM measures the brake pedal position and sends brake pedal travel status via GMLAN serial data circuit to the ECM. The ECM disengages the ACC System when the brake is applied by the driver pressing the brake pedal.
5. The IPM serves as a gateway to the display systems, instrument panel cluster (IPC), DIC and amplifier, visual and audible warnings. The IPM will generate visual and audible warnings based on high speed GMLAN serial data messages from the DSCC module.

Engine Control Module (ECM)

The following are the ACC System functions performed by the ECM

1. The ECM provides the electronic throttle control to the ACC System. The ECM is also responsible for determining when a driver is overriding the adaptive cruise control throttle position by pressing the accelerator pedal.
2. The ECM processes the cruise control switch requests received via the GMLAN serial data circuit from the IPM. Engaging and disengaging the ACC System are functions performed by the ECM.
3. The ECM determines the driver selected vehicle speed. Unless the ACC module requests a lower vehicle speed, the ECM will control the vehicle speed to the driver selected set speed.
4. The ECM allows automatic braking without disengaging the ACC.

Antilock Brake System (ABS)

The following are the ACC System functions performed by the EBCM

1. The EBCM controls the operation of the Antilock Brake System.
2. The EBCM provides automatic braking for the ACC System. The DSCC module will request vehicle deceleration via high speed GMLAN serial data circuit.
3. The EBCM determines when the driver-applied brake pressure is active. The EBCM will communicate this status via the GMLAN serial data circuit to the IPM.
4. The EBCM releases vehicle automatic braking when there is a throttle override by the driver pressing the accelerator.
5. The EBCM predicts brake temperatures. Due to automatic braking, the brake system may overheat. When the brakes are overheated, the EBCM requests the ACC System to be temporarily shut down by the ECM until the brakes cool to a normal operating temperature.

Refer to ABS Description and Operation .

Transmission Control Module (TCM)

The transmission control module (TCM) provides a down shift to protect the brakes. When the TCM detects some driver braking activity or ACC automatic braking activity, the TCM down shifts the vehicle transmission to increase engine braking. This helps reduce braking activity, extend brake pad life and reduce brake system overheating.

Driver Information Center (DIC)

The DIC is a part of the IPC and displays the ACC System warning messages. The DSCC module requests messages to be displayed on the DIC by sending a GMLAN request to the IPM. The IPM sends a GMLAN serial data request to the DIC demanding the display of the warning message. When the message is acknowledged by the driver and the cause of the message resolved, the DIC turns the message off. These displays are accompanied by a chime warning internal to the DIC. The ACC System will not operate if the DIC fails. The following are the 3 ACC messages that can be displayed on the DIC

1. Service Radar Cruise
2. Cruise Not Ready
3. Clean Radar

Radio Amplifier

The amplifier receives a GMLAN serial data message from the IPM in order to request an audible warning. The chime alerts the vehicle driver to certain ACC vehicle conditions. The audible chime accompanies a visual indicator as a warning to the driver. The ACC System will not operate if the radio amplifier fails.

Brake Pedal Position (BPP) Sensor

The IPM monitors the brake pedal position (BPP) sensor in order to determine when pressure is being applied to the brake by the driver stepping on the brake pedal. The BPP sensor receives a low reference signal and a 5-volt reference from the IPM. When the brake is applied, a signal is applied from the BPP sensor through the BPP sensor signal circuit to the IPM. The IPM utilizes this signal in deciding when to command the activation of the stop lamps. The IPM continuously sends signals via the GMLAN serial data circuit to the EBCM and the ECM reflecting the brake pedal position status. This will include the initial brake travel signal required for the activation of the ACC System. The ACC System will not engage unless the initial brake pedal travel signal is valid and received by the IPM. When the IPM brake pedal position signal indicates that brake pedal pressure is being applied by the driver when the ACC System is engaged, the ECM immediately disengages the ACC System. Re-engaging the ACC System will require the driver pressing the set or resume switch. Refer to Brake Pedal Position Sensor Calibration and to Exterior Lighting Systems Description and Operation for more information on the brake pedal pressure sensor.

Accelerator Pedal

Deceleration of the ACC vehicle to maintain a certain distance and speed while a slower moving vehicle is in its path is achieved through throttle control by the ECM and the application of light automatic braking by the EBCM. During automatic braking the ECM is commanded to release the throttle by the DSCC module. The DSCC module via the GMLAN serial data circuit requests the ECM to release the throttle from the currently controlled cruise position. At the end of automatic braking, the ECM will control the vehicle speed to the current set vehicle speed. Driver throttle override occurs when the driver of the ACC vehicle depresses the accelerator pedal with the intention of requesting greater speed than the current throttle position. An example is an ACC vehicle driver stepping on the accelerator for a passing maneuver. The ECM continuously monitors the throttle and reports a throttle override condition. When no throttle override is present, automatic braking is allowed. When throttle override is detected by the ECM, automatic braking in not allowed to affect the vehicle acceleration.

Cruise Control Switch

The cruise control switch, functionally is a common feature that is shared between the Adaptive Cruise Control (ACC) System and the regular Cruise Control System. The ACC System will not operate if any cruise switch fails. The cruise control switch comprises the following cruise control function switches

1. On/off switch
2. Set/decrease switch
3. Resume/increase switch

The cruise control function switches are arranged in a resistive ladder design whereby each switch function is set up with different resistance values. The instrument panel module (IPM) through the cruise control switch signal circuit detects a predetermined voltage value when any cruise control switch function is activated. The associated cruise control function signal detected by the IPM is then sent to the engine control module (ECM) as a GMLAN serial data circuit message. The ECM on receiving the message provides the cruise control function requested by the IPM. The ECM is responsible for recognizing and responding to cruise control switch requests sent by the IPM. The cruise control function switches are used by the ECM to communicate to the distance sensing cruise control (DSCC) module the driver selected vehicle speed. The driver selected vehicle speed is communicated through GMLAN serial data circuit to the DSCC module and the IPM. The ACC System engages and adjusts vehicle speeds based on the activation of the following cruise control function switches

On/Off Switch

The IPM monitors the cruise control set/coast and resume/accel switch signal circuit in order to determine when the On/Off switch is disabled or activated. The IPM detects a predetermined voltage value on the cruise control set/coast and resume/accel switch signal circuit. The On/Off switch state is then relayed to the ECM via the GMLAN serial data circuit. The ECM sends the On/Off switch input status to the DSCC module. When the On/Off switch is turned ON, the ACC System enters either a standby enabled or a standby disabled mode. The standby enabled mode indicates that every condition required for the ACC System to function has been met, but the ACC is not engaged. When the ACC is in the standby disabled mode, the conditions necessary for the ACC System to function has not been met. When the On/Off switch is turned OFF, the ACC will enter the disabled mode. The ACC will not activate in the disabled mode. When the automatic braking is active and the ACC On/Off switch is turned OFF, the ACC will delay entering the disabled mode.

Set/Decrease Switch

The ACC System is engaged when the ACC On/Off switch is turned ON and the set/decrease switch is momentarily pressed and released. When the set/decrease switch is pressed, the selected vehicle speed is set to the current vehicle speed by the ECM. The vehicle speed must be at or greater than 48 km/h (30 mph). While in the engaged state, the selected vehicle speed and the following distance can be adjusted. Pressing and holding the set/decrease switch, when the ACC System is engaged, will decrease the selected vehicle speed without deactivating the ACC. Momentarily pressing and releasing the set/decrease switch, when the ACC is engaged, decreased the selected vehicle speed by 1.6 km/h (1 mph) for each time that the set/decrease switch is pressed.

Resume/Increase Switch

The resume/increase switch is used in order to increase the selected vehicle speed when ACC is active. The amount selected vehicle speed can be increased from the resume/increase switch depends on how long the switch is pressed. The presence of a slower moving vehicle in the path of the ACC vehicle will limit the extent to which the selected vehicle speed can be achieved. If there is no preceding vehicle in front, limiting the ACC vehicle acceleration, then the vehicle speed that is attained is the new selected vehicle speed. Acceleration is terminated when the resume/increase switch is released. Momentarily pressing and releasing the resume/increase switch will allow the selected vehicle to accelerate in at 1.6 km/h (1 mph) increments for each time that the resume/increase switch is momentarily pressed.

Gap Up/Down Switch

The gap up/down switch allows the driver to determine how closely the adaptive cruise control (ACC) vehicle follows a target vehicle while ACC is engaged. When the ACC vehicle speed is being limited due to a slower travelling vehicle, the ACC vehicle speed is automatically controlled to the follow speed limit. The gap switch has 6 following distance selections that range from 1-2 seconds. The gap switch following distance between the ACC vehicle and the target vehicle is expressed in time as opposed to actual distance. The distance maintained for a selected gap will vary based on vehicle speed. The faster the vehicle speed, the further back you will follow. The gap setting can only be adjusted when the ACC System is engaged. The gap up/down switch is hard-wired to the instrument panel module (IPM) and voltage is provided to the switch from the IPM via the gap up/down ignition 1 voltage circuit. Based on voltage variations, the IPM is able to read the selected gap up/down switch selection and communicates the switch status on the GMLAN serial data circuit to the distance sensing cruise control (DSCC) module. The gap up/down switch is a 3 position momentary switch-Center, Gap Up and Gap Down-with the following valid signal values

1. No Activation
2. Increase Gap
3. Decrease Gap

The initial push of the gap switch recalls the current setting and activates the display. Subsequent pushes of the gap switch will change the gap setting. Momentarily pressing the gap up/down switch will adjust the switch to the desired gap setting. When the voltage from the gap up/down switch circuit is in an invalid range, the IPM will default to increasing the gap value.

SERVICE RADAR CRUISE

The DSCC module commands the display of the SERVICE RADAR CRUISE message in the driver information center (DIC) when it detects a malfunction in the Adaptive Cruise Control (ACC) System. The DSCC module sends a request to the instrument panel module (IPM) via the GMLAN serial data circuit to display the SERVICE RADAR CRUISE message in the DIC. The DIC displays the SERVICE RADAR CRUISE message when it receives a GMLAN serial data message request from the IPM. The SERVICE RADAR CRUISE is displayed in the DIC only when a diagnostic condition is present, the cruise switch is in the On position and the vehicle speed is above 48 km/h (30 mph). When the message is displayed in the DIC the ACC System disengages. The DIC sounds an internal chime anytime it displays the SERVICE RADAR CRUISE message.

CRUISE NOT READY

The DSCC module commands the display of the CRUISE NOT READY message in the DIC when ACC cannot engage due to a temporary condition. The ACC vehicle conditions that prompt the display of the CRUISE NOT READY message are temporary and do not require service. If no target is identified by the radar at the time of vehicle ignition, the CRUISE NOT READY message will be displayed in the DIC until the radar is able to identify a target. CRUISE NOT READY message is also displayed in the DIC when the DSCC transceiver is too hot and the brakes are too hot. The DIC sounds an internal chime anytime it displays the CRUISE NOT READY message.

CLEAN RADAR

The CLEAN RADAR message displays in the DIC when the DSCC module detects a blockage of the radar. The radar may be blocked by snow, ice, dirt, heavy rain or road spray. In rare instances, a vertically misaligned radar may trigger the activation of the CLEAN RADAR message in the DIC. The DSCC module commands the display of the CLEAN RADAR message via a GMLAN serial data circuit request to the IPM. The DIC displays the CLEAN RADAR message when it receives a GMLAN serial data message request from the IPM. When the CLEAN RADAR message is displayed in the DIC, safely park the vehicle and turn OFF the ignition. Clean the front fascia cover to eliminate the blockage. It may be necessary to clean both the outside surface of the cover, the inside surface of the cover and the DSCC module surface. Refer to Distance Sensing Cruise Control Maintenance for more cleaning information. It is important to turn the ignition OFF before cleaning any of the named surfaces. This is because the CLEAN RADAR message may still display in the DIC after cleaning the three surfaces. Cycling the ignition to OFF for 10 seconds is necessary to clear the CLEAN RADAR indicator if the indicator remains ON in the DIC. If the CLEAN RADAR indicator still remains ON after cleaning the radar and cycling the ignition, then the radar alignment will need to be checked and verified. Perform the Distance Sensing Cruise Control Aiming , if the radar is misaligned. The DIC sounds an internal chime anytime it displays the CLEAN RADAR message.

Cruise Engaged Indicator

The ACC engaged indicator is displayed in the driver information center (DIC) when the ACC is engaged by pressing the set/decrease switch. When the set/decrease switch is pressed by the driver, the IPM forwards the switch state to the engine control module (ECM) over the GMLAN serial data circuit. The ECM will use the switch input information from the IPM to determine the driver intended vehicle speed. The ECM communicates to the DSCC module over the GMLAN serial data circuit the ACC engaged state and the driver selected speed. When the DSCC module receives the ECM message indicating that ACC is active, the DSCC module commands the display of the ACC engaged indicator via a GMLAN serial data message to the IPM. The HUD displays the ACC engaged indicator when it receives a GMLAN serial data message from the IPM requesting the display.

Set Speed

The ACC vehicle set speed is displayed at all times in the DIC when ACC is engaged. The DSCC module set speed display request is sent to the IPM via the GMLAN serial data circuit. The DIC displays the set speed when it receives a GMLAN serial data message from the IPM requesting the set speed displayed. The DIC controls when the set speed is displayed.

Follow Distance

The DIC displays the driver selected following distance when ACC is engaged and the gap up/down switch is active. The current follow distance setting is displayed in the DIC for a few seconds after the gap up/down switch is pressed to increase or decrease the following distance. The DSCC module follow distance display request is sent to the IPM via the GMLAN serial data circuit. The DIC displays the follow distance when it receives a GMLAN serial data message from the IPM requesting the follow distance displayed in the DIC. The DIC will not display the follow distance if an indicator with a higher priority needs to be displayed in the DIC.

Vehicle Ahead Indicator

The vehicle ahead indicator is displayed in the DIC when the radar identifies an in-path vehicle. The vehicle ahead indicator is a warning to the driver that a vehicle is ahead within a distance of 100 meters (109.3 yards). The indicator also serves as a feedback to the driver that the radar is functioning properly. The DSCC module commands the display of the vehicle ahead indicator via a GMLAN serial data message to the IPM. The DIC displays the vehicle ahead indicator when it receives a GMLAN serial data message request from the IPM. The vehicle ahead indicator only displays with the ACC active and may sometimes display for stationary road objects.

Driver Alert

The driver alert indicator warns the driver of a certain road or vehicle conditions that require his attention. When the driver alert indicator flashes in the DIC it is accompanied by an audible warning from the audio amplifier. The driver alert indicator flashes in the DIC and the audible warning sounds when one of the following occurs

1. DSCC module is requesting maximum automatic braking.
2. DSCC module automatic braking request not sufficient to safely stop the vehicle in certain road conditions.
3. Cruise disengagement not initiated by driver or any driver action.
4. Vehicle speed is below 32 km/h (20 mph)
5. Abnormal cruise disengagement

The DSCC module requests the driver alert indicator and the audible warning via a GMLAN serial data message to the IPM. The IPM then sends a GMLAN serial data message to the DIC and to the audio amplifier requesting the driver alert indicator and the audible warning to be activated.

Cruise Engaged

The Adaptive Cruise Control (ACC) System will engage and adjust vehicle speeds based on the activation of the following cruise switches

1. On/off
2. Set/decrease
3. Resume/increase

ACC will not engage if any inhibit criteria is active. Also, the driver must step on the brakes at each ignition cycle before attempting to engage ACC. The engine control module (ECM) looks to the instrument panel module (IPM) for the brake initial travel achieved signal indicating that the driver has stepped on the brakes before attempting to engage ACC.

The vehicle speed must be at or above 48 km/h (30 mph) and below 188.3 km/h (117 mph) for the ACC System to be engaged. In the engaged state, the ACC System allows the driver to override the controlled vehicle speed temporarily while still remaining in the engaged state.

DSCC Module Inhibits

The distance sensing cruise control (DSCC) module inhibits the Adaptive Cruise Control (ACC) System when any of the following conditions exists

1. The RADAR NOT READY message is active in the driver information center (DIC).
2. Initial brake pedal travel signal from brake pedal position (BPP) sensor is not present
3. An ACC System malfunction and/or failure is present.
4. The CLEAN RADAR indicator is active in the DIC.
5. An invalid vehicle speed
6. The Antilock Brake System (ABS) is active during automatic braking.
7. The Cruise Switch failed message from the IPM is sent to the DSCC module.
8. Automatic braking failure-a GMLAN signal from the electronic brake control module (EBCM) the to DSCC module indicating an automatic braking failure
9. The brakes overheated signal from ABS
10. The ACC System audible warning is not present, due to an audio amplifier failure.
11. The DSCC module transceiver temperature is hot.
12. The ACC is not present-the ACC can be disabled through the IPM ACC disable feature.
13. The driver applied brake pressure.

ECM Inhibits

The ECM inhibits the ACC System operation when any of the following conditions exists

1. The ACC inhibited signal from DSCC is present.
2. The vehicle speed is at or less than 40 km/h (25 mph).
3. The vehicle speed is greater than 193.1 km/h (120 mph).
4. Automatic braking failure-a GMLAN signal from EBCM to the ECM indicating an automatic braking failure
5. The ACC present signal from the IPM is false.
6. The driver applied brake pressure.
7. A cruise control switch failure is present.
8. The park brake switch signal from the IPM is active.
9. A Throttle Actuator Control (TAC) System failure is present.
10. The Traction Control System (TCS) is active.
11. The ABS is active.
12. The engine speed protection is active.
13. The vehicle speed protection is active.
14. The engine speed is too high or too low.
15. The automatic transmission is in first gear, Park, Neutral or Reverse.
16. The initial brake pedal travel signal from the BPP sensor is not present.
17. The system voltage is too low.

Cruise Disengaged

The Adaptive Cruise Control (ACC) System disengages when any of the following occurs

1. The driver depresses the brake pedal.
2. The driver turns the ACC On/Off switch OFF.

Pressing the brake pedal while the ACC is engaged will disengage the ACC System.

Mechanical Alignment

When the radar is out of alignment, DTC C1002 is set by the distance sensing cruise control (DSCC) module. When DTC C1002 is set, it becomes necessary to mechanically align the radar using the special alignment tool. Refer to DTC C1002 . For further information on how to aim and align the radar, refer to Distance Sensing Cruise Control Aiming . An out of alignment condition may be as a result of tampering or damage to the DSCC module mounting structures or the adjuster settings. An out of alignment condition may also be as a result of damage to the front end of the vehicle or merely as a result of wear and tear. Refer to Distance Sensing Cruise Control Module Replacement on how to properly mount and adjust the DSCC module. Performance of the adaptive cruise control (ACC) System may be degraded after a DSCC module replacement. Normal vehicle driving will correct the performance of the ACC System.

Illustration Tool Number/ Description BO-047670 Adaptive Cruise Control (ACC) Radar Alignment Tool

Scheme 5

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Steering Wheel Secondary/Configurable Control Schematics
• Component Connector End Views
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Control Module References
• Inflatable Restraint Steering Wheel Module Replacement
• Diagnostic Repair Verification
• Exterior Lights Schematics
• Diagnostic Trouble Code (DTC) List - Vehicle
• Checking Aftermarket Accessories
• SIR Caution
• SIR Disabling and Enabling
• Instrument Cluster Schematics
• Indicator/Warning Message Description and Operation
• Fastener Notice
• Fascia Grille Replacement
• Throttle Actuator Control (TAC) System Description
• ABS Description and Operation
• DTC B3794
• Cruise Control Description and Operation (Conventional Cruise Control)
• Fastener Tightening Specifications
• Distance Sensing Cruise Control Maintenance