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. |
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. The BCM sends a GMLAN serial data message to the engine control module (ECM) indicating the status of the cruise control switch.
Conditions for Enabling Cruise Control
| • | The vehicle speed is greater than 40 km/h (25 mph). |
| • | The vehicle is not in PARK, REVERSE, NEUTRAL, or 1st gear. |
| • | The system voltage is within 9-16 volts. |
| • | The park brake or brakes are not applied. |
Diagnostic Aids
Important: Repair any brake system related symptoms and DTCs before performing this diagnostic.
Caution: Refer to SIR Caution in the Preface section.
Disable the inflatable restraint steering wheel module when performing this diagnostic table. Refer to SIR Disabling and Enabling .
In order to avoid misdiagnosis, inspect for the following:
| • | Ensure that the following cruise control switches are not stuck in the engaged position: |
| - | On/Off switch |
| - | - SET switch |
| - | + RES switch |
| • | Rotate the steering wheel to both steering stops and activate each cruise control switch separately. With a scan tool, observe the Cruise On/Off Switch, Cruise Resume/Accel Switch and Cruise Set/Coast Switch parameters in the ECM Cruise Control data list. This will help eliminate the possibility of an internally shorted inflatable restraint steering wheel module coil. |
| • | Inspect for proper operation of the stop lamps and the braking system. Refer to Exterior Lighting Systems Description and Operation . |
| • | Electromagnetic interference (EMI) on the speed sensor signal circuit may cause erratic cruise control operation. |
| • | For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections . |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Important: Repair any brake system related symptoms and DTCs before performing this diagnostic.
Ignition ON, cruise on/off switch ON, rotate the steering wheel to both steering stops while activating each cruise control switch separately. With a scan tool, observe all cruise control switch parameters in the ECM. Verify that each cruise control switch activated and that each displayed switch position parameters do not match or reads Invalid, as the steering wheel is turned.
| ⇒ | If the parameters match with each depressed switch accordingly, go to Diagnostic Aids. |
Circuit/System Testing
Caution: Refer to SIR Caution in the Preface section.
Disable the inflatable restraint steering wheel module when performing this diagnostic. Refer to SIR Disabling and Enabling .
Important: Repair any brake system related symptoms and DTCs before performing this diagnostic.
- Ignition OFF, remove the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
- Disconnect the harness connector C4 of the multifunction turn signal lever.
- Ignition ON, measure for 10 volts or greater at the 12-volt reference circuit terminal 1.
- Test the cruise control switch signal circuit for an open/high resistance, a short to ground or a short to voltage.
- If the circuits test normal, test the component. If the component tests normal, replace the ECM.
| ⇒ | If less than the specified value, check for an open/high resistance or a short to ground on the multifunction turn signal lever control supply voltage circuit. |
Component Testing
Caution: Refer to SIR Caution in the Preface section.
Disable the inflatable restraint steering wheel module when performing this diagnostic. Refer to SIR Disabling and Enabling .
Important: The cruise control switch must be ON in order to properly measure the resistance of the - SET and the + RES switches.
- Ignition OFF, remove the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
- Disconnect the harness connector C4 at the turn signal/multifunction switch.
- Cruise control switch ON, measure the resistance between terminals 1 and 5 at the cruise control switch side of the connector. Individually activate and hold each cruise control function switch and compare the resistance reading to the values on the schematic for the On, Off, - SET, and + RES switches.
| ⇒ | If any of the resistance measurements for the On, Off, - SET, and + RES switches are not within the listed resistance values, replace the turn signal/multifunction switch. |
Function Switch | Minimum Resistance Value | Maximum Resistance Value |
|---|---|---|
Off | O.L. | O.L. |
On | 6.5k Ohms | 7.1k Ohms |
- SET | 1.4k Ohms | 1.6k Ohms |
+ RES | 3.7k Ohms | 3.9k Ohms |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
