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Tahoe / Yukon Service Manual

DTC C1187-C118C or C118E-C1193

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. DTC Descriptors DTC C1187 Left Front Air Spring Pressure Above Threshold DTC C1188 Right Front Air Spring Pressure Above Threshold DTC C1189 Left Rear Air Spring Pressure Above Threshold DTC C118A Right Rear Air Spring Pressure Above Threshold DTC C118B Left Front Air Spring Pressure Below Threshold DTC C118C Right Front Air Spring Pressure Below Threshold DTC C118E Left Rear Air Spring Pressure Below Threshold DTC C118F Right Rear Air Spring Pressure Below Threshold DTC C1190 Left Front Intake Accumulator Performance DTC C1191 Right Front Intake Accumulator Performance DTC C1192 Left Rear Intake Accumulator Performance DTC C1193 Right Rear Intake Accumulator Performance For symptom byte information, refer to Symptom Byte List. Circuit/System Description A single pressure sensor that is internal to the Air Suspension Controller provides a signal to the K5 Automatic Level Control Module, which interprets the voltage to determine the pressure in the components of the system. Conditions for Running the DTC Updated during active leveling event. Conditions for Setting the DTC C1187, C1188, C1189, or C118A The K5 Automatic Level Control Module measures the pressure is greater than 14.3 bar. C118B, C118C, C118E, or C118F The K5 Automatic Level Control Module measures the pressure is less than 0.6 bar. C1190, C1191, C1192, or C1193 The K5 Automatic Level Control Module determines that 15 intake events have completed without exhaust event or a single intake event took longer than 300sec. Action Taken When the DTC Sets System offline. Speed limited possible. The K5 Automatic Level Control Module sends a message to the instrument panel cluster to display SERVICE LEVELING SYSTEM message. Conditions for Clearing the DTC A present DTC will clear on the next consecutive malfunction-free ignition cycle. A history DTC will clear after 41 consecutive malfunction-free ignition cycles. Diagnostic Aids Air line proper seating or damage is the primary cause for DTC to set. Inspection needs to be thorough. Corner of vehicle high or low can be directly related to DTCs and indicate what part of system has a fault. If a corner is low, an air spring leak may be present.. Remove the lower protective boot, using a soap and water solution, test for leaks at the upper mount and lower spring seat area’s. Reference Information Schematic Reference Electronic Suspension Control Schematics Connector End View Reference Master Electrical Component List Description and Operation Electronic Suspension Control Description and Operation 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. With vehicle on level ground, perform Pneumatic Connection Pressure Test using the scan tool.
  3. Verify Pneumatic Connection Pressure Test passes and corners of vehicle are not excessively high or low. ⇒ If test fails or corners are high or low Refer to Circuit/System Testing ⇓ If test passes and corners are equal
  4. A fault is not currently present and may be an intermittent condition. Circuit/System Testing
  1. Ignition OFF and all vehicle systems OFF.
  2. Inspect the appropriate air lines for damage or improper seating. ⇒ If an issue is found Repair or replace as necessary ⇓ If an issue is not found
  3. Clear DTCs. Operate system under the Conditions for Running the DTC.
  4. Verify DTCs do not reset. ⇒ If DTC sets Replace the K5 Automatic Level Control Module ⇓ If the DTC does not set
  5. A fault is not currently present and may be an intermittent condition. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Control Module References for K5 Automatic Level Control Module replacement, programming and setup.