The cruise control switch is an input to the engine control module (ECM) with (LS4), or the powertrain control module (PCM) with (L26). 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.

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, Set, and Cancel as the applicable switch is pressed.

1. Ignition OFF, disconnect the X4 harness connector at the turn signal/multifunction switch.
2. 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.

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

⇒	If not the specified value, test the signal circuit terminal 5 for a short to voltage. If the circuit tests normal, replace the ECM with (LS4), or PCM with (L26).

4. Install a 3A fused jumper wire between the signal circuit terminal 5 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), or PCM with (L26).

5. If all circuits test normal, test or replace the turn signal/multifunction switch.

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, disconnect the X4 harness connector at the turn signal/multifunction switch.
2. Cruise control switch ON, measure the resistance between terminals 1 and 5 on 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 in the table for the appropriate switch.

⇒	If any resistance measurements for any of the switches are not within the listed resistance values, replace the turn signal/malfunction switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.