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Tahoe / Yukon Service Manual

Cooling Fan Malfunction (L84, L87)

DTC P0494, P2CB9, P30EE-P30F1, U0632, U0633, U1314, or U1315 - Cooling Fan Malfunction (L84, L87) Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions DTC Descriptor DTC P0494 Cooling Fan Speed Too Low — Left Side DTC P2CB9 Cooling Fan 2 Underspeed — Right Side DTC P30EE Cooling Fan Speed Too Low — Internal Component Fault — Left Side DTC P30EF Cooling Fan Speed Too High — Internal Component Fault — Left Side DTC P30F0 Cooling Fan 2 Speed Too Low — Internal Component Fault — Right Side DTC P30F1 Cooling Fan 2 Speed Too High — Internal Component Fault — Right Side DTC U0632 Lost Communication with Cooling Fan — Left Side DTC U0633 Lost Communication with Cooling Fan 2 — Right Side DTC U1314 Invalid Data Received from Cooling Fan — Left Side DTC U1315 Invalid Data Received from Cooling Fan 2 — Right Side Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performanc e
B+ — Terminal 2 @ G10L Cooling Fan Motor - Left U0632 U0632 — U1314
Control — Terminal 4 @ G10L Cooling Fan Motor - Left U0632 U0632 U0632 U1314
Ground — Terminal 1 @ G10L Cooling Fan Motor - Left — U0632, U0633, U067C — —
B+ — Terminal 2 @ G10R Cooling Fan Motor - Right U0633 U0633 — U1315
Control — Terminal 4 @ G10R Cooling Fan Motor - Right U0633 U0633 U0633 U1315
Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performanc
Ground — Terminal 1 @ G10R Cooling Fan Motor - Right — U0632, U0633, U067C — —

Circuit/System Description For an overview of the component/system, refer to: Cooling Fan Description and Operation

Circuit Description
B+ Supplied from a fuse.
Serial Data Digitally encoded information for communication between devices.
Ground Chassis Ground
Component Description
G10L Cooling Fan Motor - Left G10R Cooling Fan Motor - Right An electric DC motor.
K20 Engine Control Module The control module contains a microprocessor used to process input data to control outputs. The control module controls a series of actuators to ensure optimal engine performance. The control module does this by reading values from a variety of sensors, interprets the data and adjusts the engine actuators accordingly.

Conditions for Running the DTC { P30EE, P30EF, P30F0, P30F1 } DTC U0632, U0633, U1314, U1315 = Not set Cooling Fan = Commanded On Ignition = On Ignition Voltage = Greater than 11 V { U0632, U0633, U1314, U1315 } Power Mode = Run Frequency the DTC runs = Continuously — After the running conditions are met Conditions for Setting the DTC P0494, P2CB9 Cooling Fan Speed / Cooling Fan 2 Speed = Commanded state does not match the actual state — For greater than 16 s P30EE, P30F0 Cooling Fan Speed / Cooling Fan 2 Speed = Less than 110 RPM Less than a predefined threshold — For greater than 16 s P30EF, P30F1 Cooling Fan Speed / Cooling Fan 2 Speed = Greater than 3,999 RPM or Greater than a predefined threshold — For greater than 16 s U0632, U0633 Serial data message from component: G10L Cooling Fan Motor - Left / G10R Cooling Fan Motor - Right = Not Received — For greater than 1 s U1314, U1315 Serial data message from component: G10L Cooling Fan Motor - Left / G10R Cooling Fan Motor - Right = Invalid Data Received — For greater than 1 s Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type B DTC Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type B DTC Diagnostic Aids A DTC may set depending on certain driving conditions and would not require a component replacement. The following conditions could cause DTC P0494, P2CB9 to set: Cold Regions = Ice / Snow @ G10 Cooling Fan Motor — Blade & Engine Coolant Fan Shroud Dry Regions = Dirt / Dust / Sand @ G10 Cooling Fan Motor — Blade & Engine Coolant Fan Shroud Wet Regions = Dirt / Mud @ G10 Cooling Fan Motor — Blade & Engine Coolant Fan Shroud Reference Information Schematic Reference Engine Heating/Cooling Schematics Connector End View Reference Master Electrical Component List Component View Reference Component Connector End Views Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions Scan Tool Reference Control Module References Circuit/System Verification

  1. Engine » Idling
  2. Verify DTC U1345 is not set. ⇒ If the DTC is set Refer to: DTC U1345-U1349 ⇓ If the DTC is not set
  3. Verify DTC U0632, U0633 U1314, U1315 is not set. ⇒ If any of the DTCs are set Refer to: Circuit/System Testing ⇓ If none of the DTCs are set
  4. Verify DTC P30EE, P30EF, P30F0, P30F1 is not set. ⇒ If any of the DTCs are set Replace the appropriate component: G10 Cooling Fan Motor ⇓ If none of the DTCs are set
  5. Ignition/Vehicle » Off
  6. Verify a condition does not exist with the component: Cooling Fan Motor — Binding or Sticking / Worn / Visible Damage Blade — Cracked / Missing / Visible Damage Blade / Engine Coolant Fan Shroud — Blocked by debris / Foreign objects For example: – Ice – Mud – Snow ⇒ If a condition exists Repair or replace as necessary ⇓ If no condition exists
  7. Ignition » On / Vehicle » In Service Mode
  8. Perform the scan tool function: Clear the DTCs.
  9. Engine » Idling
  10. Perform the appropriate scan tool control function: { P0494, P30EE, P30EF } Cooling Fan » 50% — For 2 min { P2CB9, P30F0, P30F1 } Cooling Fan 2 » 50% — For 2 min Verify DTC P0494, P2CB9, P30EE, P30EF, P30F0, P30F1 is not set. ⇒ If any of the DTCs are set Replace the appropriate component: G10 Cooling Fan Motor ⇓ If none of the DTCs are set
  11. Ignition » On / Vehicle » In Service Mode
  12. Perform the appropriate scan tool control function: { Left Side } Cooling Fan » Command the component to the maximum position/speed { Right Side } Cooling Fan 2 » Command the component to the maximum position/speed Verify a condition does not exist with the component: Cooling Fan — Turns Off – Perform the action while monitoring the component: Wiggle the harness and connector: G10L Cooling Fan Motor - Left Wiggle the harness and connector: G10R Cooling Fan Motor - Right Wiggle the harness and connector: K20 Engine Control Module Wiggle the harness and connector: X50A Engine Wiring Harness Junction Block Wiggle the component: Fuse @ X50A Engine Wiring Harness Junction Block ⇒ If a condition exists Repair as necessary » Wiring / Terminal(s) / Electrical Connector(s) ⇓ If no condition exists
  13. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. Verify the DTC does not set. ⇒ If the DTC sets Repeat the procedure starting at step 2 ⇓ If the DTC is not set
  14. All OK. Circuit/System Testing
  15. Ignition/Vehicle & All vehicle systems » Off
  16. Disconnect the appropriate electrical connector: G10 Cooling Fan Motor
  17. Test for less than 5 Ω between the test points: Ground circuit terminal 1 & Ground ⇒ If 5 Ω or greater 3.1. Disconnect the ground connection: Ground terminal 3.2. Test for less than 2 Ω between the test points: Ground circuit terminal 1 @ Component harness & The other end of the circuit @ Ground terminal ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Repair the open/high resistance in the ground connection. ⇓ If less than 5 Ω
  18. Ignition » On / Vehicle » In Service Mode
  19. Verify a test lamp turns On between the test points: B+ circuit terminal 2 & Ground ⇒ If the test lamp does not turn On and the circuit fuse is OK 5.1. Ignition/Vehicle » Off & Remove » Test lamp 5.2. Test for less than 2 Ω between the test points: B+ circuit terminal 2 & Output terminal @ Fuse ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Verify the fuse is OK and there is voltage at the fuse. ⇒ If the test lamp does not turn On and the circuit fuse is open 5.1. Ignition/Vehicle » Off & Remove » Test lamp 5.2. Test for infinite resistance between the test points: B+ circuit terminal 2 & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇒ If infinite resistance » Replace the component: G10 Cooling Fan Motor ⇓ If the test lamp turns On
  20. Connect a DMM between the test points: Serial Data circuit terminal 4 @ Component harness & Ground Verify the DMM displays between 3.5 and 12 V & Fluctuates ⇒ If less than 3.5 V and does not fluctuate 6.1. Ignition/Vehicle » Off 6.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 6.3. Test for infinite resistance between the test points: Serial Data circuit terminal 4 @ Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇓ If infinite resistance 6.4. Test for less than 2 Ω between the test points: Serial Data circuit terminal 4 @ Component harness & The other end of the circuit @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K20 Engine Control Module ⇒ If greater than 12 V and does not fluctuate 6.1. Ignition/Vehicle » Off 6.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 6.3. Ignition » On / Vehicle » In Service Mode 6.4. Test for less than 1 V between the test points: Serial Data circuit terminal 4 @ Component harness & Ground ⇒ If 1 V or greater » Repair the short to voltage on the circuit. ⇒ If less than 1 V » Replace the component: K20 Engine Control Module ⇓ If between 3.5 and 12 V and fluctuates
  21. Test or replace the component: G10 Cooling Fan Motor Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Engine Cooling Fan Motor Replacement For control module replacement, programming, and setup refer to: Control Module References