For 1990-2009 cars

### 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 on/off, set/coast, and resume/accelerate switch signal circuits in order to detect when a cruise control function switch has been activated. The BCM detects a predetermined voltage signal when a cruise control function switch is applied, with each switch having a different voltage value. The BCM sends a GMLAN serial data message to the engine control module (ECM)/powertrain control module (PCM) indicating the status of the cruise control switches.

### 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

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:

• | Proper operation of the brake lamps--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

Cruise Control Schematics

#### Connector End View Reference

Cruise Control Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Circuit/System Verification

1. Ensure that the following cruise control switches are not stuck in the engaged position:

• | ON/OFF switch

• | - Set switch

• | + RES switch

2. Inspect for proper operation of the stop lamps. Refer to Exterior Lighting Systems Description and Operation .
3. Rotate the steering wheel to both steering stops while activating each cruise control switch separately. With a scan tool, observe the Cruise Control Switch parameter in the BCM. Ensure that each cruise control switch activated and that each displayed switch position in the Cruise Control Switch parameter do not match as the steering wheel is turned.

⇒ | If the displayed switch positions in the Cruise Control Switch parameter match with each depressed switch accordingly, replace the ECM (non 2.0L)/PCM (2.0L).

### 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 .

1. Ignition OFF, remove the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
2. Disconnect the harness connector of the cruise control on/off switch.
3. Ignition ON, measure for 10 volts or greater at the cruise control supply voltage circuit.

⇒ | If less than 10 volts, check for an open/high resistance or for a short to ground on the cruise control supply voltage circuit.

4. Ignition OFF, disconnect the harness connector of the set/cruise, resume/accelerate switch. Test for an open/high resistance, a short to ground, or a short to voltage in the cruise control switch signal circuit between the BCM and the set/cruise, resume/accelerate switch.
5. Test for an open/high resistance, a short to ground, or a short to voltage in the cruise control switch signal circuit between the cruise control on/off switch and the set/cruise, resume/accelerate switch.
6. Test the component. If the circuits and the component tests are normal, replace the BCM.

### 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 .

1. Ignition OFF, remove the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
2. Disconnect the harness connector at the cruise control on/off switch.
3. Verify that there is continuity between the voltage supply circuit and the cruise control switch signal circuit when switched ON, and open when switched OFF.

⇒ | If the resistance does not show continuity when switched ON and open when switched OFF, replace the cruise control on/off switch assembly.

4. Disconnect the harness connector at the cruise control set/cruise, resume/accelerate switch assembly.
5. Cruise control switch ON, measure the resistance between terminals 7 (UK3) or 4 (without UK3) and 6 (UK3) or 3 (without UK3) 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 - SET and the + RES.

⇒ | If any of the resistance measurements for the - SET and + RES are not within the listed resistance values, replace the cruise control set/cruise, resume/accelerate switch assembly.

Function Switch | Minimum Resistance Value | Maximum Resistance Value
--- | --- | ---
OFF | O.L. | O.L.
ON | 0.0k Ohms | 0.5k Ohms
- SET | 1.2k Ohms | 1.3k Ohms
+ RES | 2.7k Ohms | 3.0k Ohms

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Steering Wheel Control Switch Assembly Replacement

• | Control Module References for BCM, PCM (2.0L), or ECM (non 2.0L) replacement, setup, and programming