The cruise control switch is an input to the body control module (BCM) and to the engine control module (ECM) with (LS4/LY7), or the powertrain control module (PCM) with (L26). The BCM monitors the cancel switch, and the ECM/PCM monitors the cruise control ON/OFF, Set/Coast, and the Resume/Accelerate switch signal circuits in order to detect when a cruise control function switch has been activated. The ECM/PCM detects a predetermined voltage signal when a cruise control function switch is applied, with each switch having a different voltage value.

The ECM/PCM detects that the Resume/Accel. switch is applied for longer than 90 seconds.

Schematic Reference

Cruise Control Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Engine ON, while rotating the steering wheel to both steering stops, observe the scan tool Cruise Control Switch parameter while pressing each of the cruise control switches. The parameter should toggle between ON, OFF, Resume and Set as the applicable switch is pressed.

1. Ignition OFF, disconnect the harness connector at the steering wheel controls switch - left.
2. Ignition OFF, test for less than 10 ohms between the ground circuit terminal 8 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, test for B+ between the ignition voltage circuit terminal 1 and ground.

⇒	If less than the specified value, test the ignition voltage circuit for a short to ground or an open/high resistance.

4. Ignition ON, test for B+ between the ignition voltage circuit terminal 1 and cruise control cancel switch terminal 5.

⇒	If less than the specified range, test the cruise control cancel circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

5. Verify the scan tool Cruise ON/OFF switch parameter displays OFF.

⇒	If not the specified value, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the ECM with (LS4/LY7), or PCM with (L26).

6. Install a 3A fused jumper wire between the signal circuit terminal 3 and the ignition voltage circuit terminal 1. Verify the scan tool Cruise ON/OFF Switch parameter displays ON.

⇒	If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM with (LS4/LY7), or PCM with (L26).

7. If all circuits test normal, test or replace the steering wheel controls switch - left.

Important: The cruise control switch must be ON in order to properly measure the resistance of the - /SET, and +/RES, switches.

1. Disconnect the harness connector at the steering wheel control switch-left.
2. Connect a DMM between terminals 1 and 3 signal circuit or terminals 1 and 5 for the cancel switch circuit of the steering wheel control switch-left.
3. Cruise control switch ON, measure the resistance while individually activating and holding each cruise control function switches 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 specified resistance values, replace the steering wheel control switch-left.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.