Express 1500 RWD V8-5.3L (2008)
Important: Repair any brake system related symptoms and DTCs before performing this diagnostic.
In order to avoid misdiagnosis, inspect for the following:
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Verify there are no DTCs set as current. If any DTCs are set as current, refer to Diagnostic Trouble Code (DTC) List - Vehicle and perform the
appropriate diagnostics/repairs before proceeding with symptom based diagnostics. See: Powertrain Management/Computers and Control
Systems/Testing and Inspection/Diagnostic Trouble Code Descriptions
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Inspect the cruise control switches for any sticking or binding conditions.
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Inspect for proper operation of the stop lamps.
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With the ignition 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. Ensure that each cruise control switch activates and that each of the displayed switch
position parameters match the currently activated switch, and do not read Error. This may aid in locating an intermittent fault within the inflatable
restraint steering wheel module coil.
Circuit/System Verification
Ignition ON, cruise on/off switch ON. With a scan tool, observe the scan tool Cruise Control Switch parameter in the BCM. While pressing each of the
cruise control switches, the scan tool display should change to display the current switch being actuated. Road test the vehicle to ensure the cruise control
system functions as described in Cruise Control Description and Operation.
Circuit/System Testing
1. Ignition OFF, remove the inflatable restraint steering wheel module.
2. Disconnect the harness connector at the cruise control switch.
3. Ignition ON, test for B+ between the supply circuit terminal 1 and ground.
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If less than the specified range, test the supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the
BCM.
4. Verify the scan tool Cruise Control Switch parameter is OFF.
^
If not the specified value, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the BCM.
5. Ignition OFF, connect the harness connector at the cruise control switch.
6. Ignition ON, cruise control switch ON, observe the scan tool Cruise Control Switch parameter. The parameter should display ON.
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If not the specified value, test the signal circuit terminal 3 for a short to ground or an open/high resistance. If the circuit tests normal, test or
replace the cruise control switch.
7. Observe the scan tool Cruise Control Switch parameter while pressing the RES + portion of the cruise control switch. The parameter should
display Resume.
^
If not the specified value, test or replace the cruise control switch.
8. Observe the scan tool Cruise Control Switch parameter while pressing the SET - portion of the cruise control switch. The parameter should display
Set.
^
If not the specified value, test or replace the cruise control switch.
9. Observe the scan tool Cruise Control Switch parameter while pressing the Cancel portion of the cruise control switch. The parameter should
display Cancel.
^
If not the specified value, test or replace the cruise control switch.
10. If all circuits and the component test normal, replace the BCM.
Component Testing
Important: The cruise control switch must be ON in order to properly measure the resistance of the - /SET, the +/ RES, and the Cancel
switches.
1. With the ignition OFF, remove the inflatable restraint steering wheel module.
2. Remove the steering wheel cruise control switch.
3. 3. Connect a DMM between terminals 1 and 3 of the cruise control switch. Cruise control ON/OFF switch ON, measure the resistance while
individually activating and holding each cruise control function switch and compare the resistance reading to the values in the table for the
