Skip to content
Tahoe / Yukon Service Manual

Adaptive Cruise Control Malfunction

Diagnostic Instructions 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. Diagnostic Fault Information

Circuit Number Circuit Function Short to Ground Open/High Resistance Short to Voltage Signal Performan
5737 Signal 2, 3, 4 2, 3, 4 2, 3, 4 —
1449 Low Reference — 1 — —
1. Cruise control inoperative 2. Unable to change adaptive cruise control following distance 3. Unable to disable lane keep assist 4. Cruise control set and resume second detent function inoperative

Circuit/System Description For an overview of the adaptive cruise control system, refer to Adaptive Cruise Control Description and Operation. Diagnostic Aids The adaptive cruise control system can be inhibited or disengaged for a number of reasons. These reasons may be a normal function of the vehicle or as a result of action the driver has taken. They also may be because of a fault in a vehicle system. The K124 Image Processing Module has an available scan tool data list that can help identify what may have caused an adaptive cruise control inhibit or disengage. The scan Adaptive Cruise Control Disable History Data list identifies conditions that will cause an adaptive cruise control inhibit, which would prevent adaptive cruise control from engaging when requested by the driver, or that will cause an adaptive cruise control disengage, which would immediately disengage adaptive cruise control if the driver was actively utilizing the system. When attempting to diagnose the system, it is important to discuss with the customer the conditions under which the apparent malfunction occurred. This is critical to help identify those scenarios where the inhibit or disengage is the result of a driver action or normal system response and clarify how the function works. It is also critical to identify when the apparent malfunction occurred when attempting to replicate the condition. The parameters in the scan tool Adaptive Cruise Control Disable History Data list can be used to help isolate what is causing an inhibit or disengage condition. The scan tool Adaptive Cruise Control Disable History Data list has parameters that identify the last eight causes of an inhibit and the last eight causes of a disengage. For each Adaptive Cruise Control Inhibit History and Adaptive Cruise Control Disengage History parameter, extra information is included in additional parameters: Odometer at First Malfunction, Odometer at Last Malfunction, Diagnostic Status, Malfunction Counter, and Ignition Cycles Since Last Diagnostic Event. The scan tool parameters are a rolling snapshot of the last eight inhibit and disengage reasons, however, if the same condition causes an inhibit or disengage, the reason will not be logged in the next parameter. Instead, the Malfunction Counter parameter will increment and the Odometer at Last Malfunction parameter will update with the most recent odometer value that the condition occurred. When diagnosing an inhibit or disengage concern, especially in the case of an intermittent condition, these parameters are useful in helping determine the cause. Recurring causes will have a larger number in the Malfunction Counter parameter and will likely have a wide variance between the Odometer at First Malfunction and Odometer at Last Malfunction value, indicating the condition has occurred over a period of time driving the vehicle. Refer to: Driver Assistance Systems Disable History Conditions Reference Information Schematic Reference Driver Assistance Systems Schematics Connector End View Reference Master Electrical Component List Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Scan Tool Reference Control Module References for scan tool information Circuit/System Verification

  1. Ignition ON.
  2. Verify there are no DTCs set. ⇒ If any DTC’s are set Refer to Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If no DTC’s are set
  3. Drive the vehicle.
  4. Verify the lane keep assist and forward collision alert systems are able to be turned on and off using their respective control switches, function properly, and there are no service messages displayed related to either system. ⇒ If the lane keep assist and forward collision alert system is not operating properly Diagnose any faults in these systems prior to diagnosing the adaptive cruise control system. Refer to Symptoms - Driver Assistance Systems. ⇓ If the lane keep assist and forward collision alert system are operating properly
  5. Press and release the Adaptive Cruise Control Gap Switch. Verify the adaptive cruise control gap setting on the P9 Driver Information Center Display changes between Far, Medium, and Near with each button press. ⇒ If the gap setting does not change Refer to Circuit/System Testing. ⇓ If the gap setting changes
  6. Drive the vehicle.
  7. Verify the adaptive cruise control system is able to be engaged and disengaged normally and all systems functions are operating as designed. ⇒ If the adaptive cruise control system malfunction is identified Use the scan tool Adaptive Cruise Control Disable History Data parameters as described in Diagnostic Aids to identify the cause of the inhibit or disable condition and diagnose and repair as necessary. ⇓ If the adaptive cruise control system is operating as designed
  8. All OK. A fault is currently not present and may be an intermittent condition. Refer to Diagnostic Aids. Circuit/System Testing
  9. Ignition OFF, disconnect the X2 and X4 connectors at the K9 Body Control Module, Ignition ON.
  10. Test for less than 1 V between signal circuit terminal 13 X2 and ground. ⇒ If 1 V or greater Repair the short to voltage on circuit 5737. ⇓ If less than 1 V
  11. Ignition OFF
  12. Test for infinite resistance between signal circuit terminal 13 X2 and ground. ⇒ If less than infinite resistance 4.1. Test circuit 5737 for a short to ground. ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found 4.2. Replace the S70L Cruise Control Switch. ⇓ If infinite resistance
  13. Test for 14.0 k to 14.5 kΩ between signal circuit terminal 13 X2 and low reference circuit terminal 3 X4. ⇒ If not between 14.0 k and 14.5 kΩ 5.1. Test circuit 5737 for an open/high resistance. ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open/high resistance is not found 5.2. Test circuit 1449 for an open/high resistance. ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open/high resistance is not found 5.3. Replace the S70L Cruise Control Switch. ⇓ If between 14.0 k and 14.5 kΩ
  14. Test for 3.3 k to 3.7 kΩ between signal circuit terminal 13 X2 and low reference circuit terminal 3 X4 while pressing and holding the adaptive cruise control gap switch. ⇒ If not between 3.3 k and 3.7 kΩ Replace the S70L Cruise Control Switch. ⇓ If between 3.3 k and 3.7 kΩ
  15. Replace the K9 Body Control Module. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Driver Assistance Systems Component Replacement Reference For control module replacement, programming, and setup refer to: Control Module References