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Pete
Pete, Auto Service Technician
Category: Chevy
Satisfied Customers: 26699
Experience:  14 years GM dealer Technician.
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Chevrolet Silverado: I have a 2013 Chevy 3500 srw with a Duramax.

Customer Question

I have a 2013 Chevy 3500 srw with a Duramax. Yesterday I had a message to turn off my A/C and at that point discovered it was running hotter than normal. I pulled over and raised the hood. The fan didn't appear to be running very fast. I stopped by a parts store and bought a new rely, but that didn't change anything. Out on the highway it cooled off some as long as I didn't run the A/C.
Can you tell me if it's my fan clutch or some sensor? The fan clutch seems pretty tight, no real wobble in it. The check engine light came on last night as I pulled into the driveway, but the motor was not overheating. Please let me know. I have a friend of mine with a computer who was planning on hooking it up this evening. I don't know how to test the fan clutch either. Thank you for your time.
Submitted: 11 months ago.
Category: Chevy
Expert:  Pete replied 11 months ago.
Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay. If your model uses a fan clutch and does not have the electronic fan as some have below is the procedure on how to test this clutch assembly.I have had to replace the fan clutch on this model here before due to this issue and the check engine light coming on is most likely a fault code set for the EV fan clutch failure needing replaced. Circuit/System Description The ECM controls the EV fan clutch operation. The ECM regulates a 12-volt pulse width modulated signal (PWM) to the cooling fan relay. The PWM signal determines the ON time of the relay. As the ECM command increases, so does the ON time of the relay. The relay ON time directly controls the amount of time the solenoid, which is internal to the fan clutch, is energized. When the solenoid in the fan clutch is energized, it opens the spring loaded valve and allows fluid to flow from the storage chamber to the fluid coupling of the cooling fan clutch, which increases the fan speed. When the solenoid is de-energized, the spring loaded valve closes, and allows the fluid in the coupling of the fan clutch to drain back to the storage chamber, which reduces fan speed. The rapid modulation of the fan clutch solenoid valve gives the ECM the ability to precisely control the amount of fluid that remains in the fluid coupler, allowing more effective regulation of the fan speed and powertrain cooling requirements. Circuit/System Verification 1. Ignition OFF. 2. Verify the conditions listed below do not exist with the cooling fan system: * A loose, worn, or mis-routed drive belt* Oil leaks at the cooling fan clutch * A free-spinning cooling fan * A seized cooling fan clutch * A broken cooling fan * Inspect the cooling fan clutch harness connector and the fan clutch jumper harness for the conditions listed below: - Poorly mated connectors - Backed/pushed out connector terminals - Poor terminal tension - Cut, chaffed, or nicked harness wiring at the fan clutch ◊If a condition is found Repair as necessary ◊If a condition is not found 3. Ignition ON. 4. Verify DTC P0480, P0483, P0495, or P0526 is not set. ◊If a DTC is set Refer to Diagnostic Trouble Code (DTC) List - Vehicle See: A L L Diagnostic Trouble Codes ( DTC ) > Diagnostic Trouble Code Descriptions > Diagnostic Trouble Code (DTC) List - Vehicle ◊If a DTC is not set 5. Engine at operating temperature. 6. Verify the scan tool Fan Speed and Desired Fan Speed parameters are within 500 RPM while performing the test listed below: 1. Increase engine speed to 1,500 RPM Note: In each of the commanded states, it may take up to 2 minutes for the Fan Speed to achieve the Desired Fan Speed. 2. Command the Cooling Fan slowly from 10 % to 80 % with a scan tool. 3. Command the Cooling Fan to 10 % with a scan tool. ◊The Fan Speed is not within 500 RPM of the Desired Fan Speed Refer to Circuit/System Testing ◊The Fan Speed is within 500 RPM of the Desired Fan Speed 7. All OK Circuit/System Testing 1. Ignition OFF, and all vehicle systems OFF, disconnect the cooling fan relay. It may take up to 2 minutes for all vehicle systems to power down. 2. Verify a test lamp illuminates between the B+ circuit terminal 2 and ground. ◊If the test lamp does not illuminate 1. Remove the Fan Fuse. 2. Test for less than 2 ohms in the B+ circuit end to end. ◊If 2 ohms or greater, repair the open/high resistance in the circuit. ◊If less than 2 ohms, verify the fuse is OK and there is voltage at the fuse. ◊If the test lamp illuminates 3. Test for less than 5 ohms between the fan relay ground circuit terminal 6 and ground. ◊If 5 ohms or greater 1. Test for less than 2 ohms in the ground circuit end to end. ◊If 2 ohms or greater, repair the open/high resistance in the circuit. ◊If less than 2 ohms, repair the open/high resistance in the ground connection. ◊If less than 5 ohms 4. Test for 7-17 ohms between fan relay terminal 4 and terminal 6. ◊If less than 7 ohms 1. Disconnect the engine cooling fan harness connector. 2. Verify a test lamp does not illuminate between the fan relay terminal 4 and B+. ◊If the test lamp illuminates, repair the short to ground in the solenoid valve control circuit terminal 4. ◊If the test lamp does not illuminate, test the circuits of the jumper harness for a shorted condition. If the jumper harness tests normal, replace the cooling fan clutch assembly. ◊If greater than 17 ohms 1. Disconnect the engine cooling fan harness connector. 2. Test for less than 2 ohms between relay terminal 4 and fan harness connector terminal B. ◊If 2 ohms or greater, repair the open/high resistance in the fan clutch solenoid valve control circuit. ◊If less than 2 ohms. 3. Test for less than 2 ohms between the fan harness connector terminal A and ground. ◊If 2 ohms or greater, repair the open/high resistance in the circuit. ◊If less than 2 ohms, test the circuits of the jumper harness for an open/high resistance condition. If the jumper harness tests normal, replace the cooling fan clutch assembly. ◊If within 7-17 ohms 5. Engine operating, connect a 10 A fused jumper wire between fan relay terminal 4 and B+. Note: It may take several minutes for the fan clutch to fully engage with the engine at idle. 6. Verify the fan gets much louder to indicate the fan clutch is engaged. Note: It may take anywhere from 10-52 minutes for the fan clutch to disengage depending on the factors below: * Engine speed * Coupler fluid temperature * Elevation above sea level 7. Disconnect the 10 A fused jumper wire from B+. The fan should become quiet to indicate the clutch is disengaged. ◊If the fan clutch doesn't engage or disengage according to the test Replace the cooling fan clutch assembly. ◊If the fan clutch engages and disengages according to the test 8. Test or replace the fan relay. Component Testing Relay Test 1. Remove the cooling fan clutch relay. 2. Connect a 10 A fused jumper wire between relay terminal 2 and B+. Connect a jumper wire between relay terminal 6 and ground. 3. Test for less than 1 V between terminal 4 and ground. ◊If greater than the specified value, replace the fan relay. 4. Connect a jumper wire between terminal 5 and ground. 5. Test for B+ between terminal 4 and ground. ◊If less than the specified value, replace the fan relay. If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.Thanks Pete
Customer: replied 11 months ago.
Thank you, ***** ***** check all of this out. I can say that with the engine off and the key off the fan turns freely. Is that supposed to be that way?
Expert:  Pete replied 11 months ago.
Your welcomeYes as the EV clutch is then released so it will turn freely like this here.I suspect the clutch needs replaced as it is the most common to fail. Let me know if you need anything else and feel free to rate my help here. Thanks Pete