• | 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. |
The cruise control switch is an input to the body control module (BCM). The BCM monitors the cruise control on/off, set/coast, resume/accelerate, and cancel 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 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 is not applied. |
Important: Repair any brake system related symptoms and DTCs before performing this diagnostic.
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 |
- | Cancel 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, Cruise Set/Coast Switch and Cruise Cancel 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. |
Cruise Control Description and Operation
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 BCM. Verify that each cruise control switch activated and that each displayed switch position parameters match accordingly with each depressed switch, as the steering wheel is turned.
⇒ | If less than 10 volts, test the 12-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
⇒ | If greater than the specified range, test the cruise control switch signal circuit for an open/high resistance. |
⇒ | If less than the specified value, test the cruise control switch signal circuit for a short to ground. |
⇒ | If greater than the specified value, test the cruise control switch signal circuit for a short to voltage. |
Important: The cruise control ON/OFF switch must be ON in order to properly measure the resistance of the - SET, the + RES, and the Cancel switches.
⇒ | If any of the resistance measurements for the OFF, ON, - SET, + RES, and Cancel switches are not within the listed resistance values, replace the cruise control switch assembly. |
Function Switch | Minimum Resistance Value | Maximum Resistance Value |
---|---|---|
OFF | O.L. | O.L. |
ON | 6.5k ohms | 7.0k ohms |
- SET | 2.2k ohms | 2.4k ohms |
+ RES | 3.7k ohms | 3.8k ohms |
Cancel | 1.4k ohms | 1.6k ohms |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for BCM replacement, setup, and programming |