Cruise Control Inoperative/Malfunctioning
Cruise Control Inoperative/Malfunctioning
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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 engine control module (ECM) / powertrain control module (PCM). The ECM (5.3L) / PCM (3.8L) monitors the cruise control set/coast and resume/accelerate switch signal circuit in order to detect when a cruise control function has been requested. The ECM detects a specific voltage signal on the cruise control set/coast and resume/accelerate switch signal circuit when a cruise control function switch is activated, with each switch having a different predetermined voltage value.
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.
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:
* Verify that DTC P0573 is not current in the PCM/ECM. If the DTC is current, go to DTC P0573. P0573
* Ensure that the following cruise control switches are not stuck in the engaged position:
- On/Off switch
- Set/Coast switch
- Resume/Accel 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/PCM 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.
* 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 in Diagnostic Aids. Component Tests and General Diagnostics
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/PCM. 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
Important: Repair any brake system related symptoms and DTCs before performing this diagnostic.
Caution: Refer to SIR Caution.
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 C4 of the multifunction turn signal lever.
3. Ignition ON, measure for 10 volts or greater at the multifunction turn signal lever control supply voltage circuit terminal 1.
• 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.
4. Test the cruise control switch signal circuit for an open/high resistance, a short to ground or a short to voltage.
5. If the circuits test normal, test the component. If the component tests normal, replace the PCM/ECM.
Component Testing
Caution: Refer to SIR Caution.
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/cruise and the resume/accel switches.
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 switch.
3. 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/cruise, and the resume/accel.
• If any of the resistance measurements for the OFF, ON, set/cruise, resume/accel are not within the listed resistance values, replace the cruise control switch assembly.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Turn Signal Multifunction Switch Replacement
* Programming and RelearningProgramming and Relearning