Cooling Fan Inoperative (LBN, LEA, LE9, LLU, or LTD)
Cooling Fan Inoperative (LBN, LEA, LE9, LLU, or LTD)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Circuit/System Description
The engine cooling fan system is composed of one cooling fan, a series of 5 relays, the engine control module (ECM), and the associated wiring. The cooling fan assembly includes two resistors. This combination of components enables the ECM to operate the cooling fan at 3 speeds using two fan control circuits.
Diagnostic Aids
* The scan tool cooling fan output control operates as follows:
- Cooling Fan Relay 1 operates the fan at a low speed
- Cooling Fan Relay 2 and 3 operates the fan at a medium speed
- Cooling Fan Relay 1, 2 and 3 operates the fan at a high speed
* When disconnecting or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.
Reference Information
Schematic Reference
Engine Cooling Schematics [1][2]Cooling System
Connector End View Reference
* Component Connector End Views Sunshade - Left (DH6)
* Electrical Center Identification Views X70A Relay Block - Underhood Top View
Description and Operation
Cooling Fan Description and Operation (LFW) Cooling Fan Description and Operation (LFW)Cooling Fan Description and Operation (LBN, LEA, LE9, LLU, or LTD) Cooling Fan Description and Operation (LBN, LEA, LE9, LLU, or LTD)
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P0480, P0481, P0691, P0692, P0693, or P0694 is not set.
• If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
2. Command the cooling fan ON and OFF at low, medium, and high speed with a scan tool. The cooling fan should turn ON and OFF in each of the commanded states, refer to Diagnostic Aids.
Circuit/System Testing
1. Ignition OFF, disconnect the KR20F cooling fan relay.
2. Test for less than 1ohms between the KR20F Cooling Fan Relay controlled output circuit terminal 87 and ground.
• If greater than the specified range, test the output circuit for an open/high resistance.
3. Install the KR20F cooling fan relay.
4. Disconnect the following KR20 relays.
* KR20C cooling fan low speed relay
* KR20D cooling fan high speed relay
* KR20E cooling fan speed control relay
* KR20P cooling fan medium speed relay
5. Ignition ON, connect a test lamp between ground and each of the KR20 relay terminals listed below. The test lamp should illuminate.
* KR20C cooling fan low speed relay terminal 85
* KR20E cooling fan speed control relay terminal 86
• If the test lamp does not illuminate, test the appropriate relay coil B+ circuit for an open/high resistance.
6. Connect a test lamp between B+ and each of the KR20 relay terminals listed below. Command the cooling fan ON at low speed with a scan tool. The test lamp should illuminate.
* KR20C cooling fan low speed relay terminal 86
* KR20E cooling fan speed control relay terminal 85
• If the test lamp does not illuminate, test the relay coil control circuit for an open/high resistance. If the circuits test normal, test or replace the KR20F relay.
7. Ignition OFF, install the KR20E cooling fan speed control relay.
8. Ignition ON, connect a test lamp between ground and the KR20D high speed relay coil B+ circuit terminal 86/1. Command the cooling fan ON at low speed with a scan tool. The test lamp should illuminate.
• If the test lamp does not illuminate, test the KR20E relay controlled output circuit and the B+ supply circuit for an open/high resistance. If the circuits test normal, test or replace the KR20E cooling fan speed control relay.
9. Ignition OFF, install all the previously removed KR20 cooling fan relays.
10. Ignition OFF, disconnect the harness connector at the G10 Engine Cooling Fan.
11. Test for less than 1.0ohms between the G10 Engine Cooling Fan ground circuit terminal 1 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
12. Ignition ON, connect a test lamp between ground and each of the G10 cooling fan circuit terminals listed below. Command the cooling fan ON at low, medium, and high speed with a scan tool. The test lamp should illuminate at each terminal as commanded.
* G10 cooling fan low speed circuit terminal 2
* G10 cooling fan medium speed circuit terminal 3
* G10 cooling fan high speed circuit terminal 4
• If the test lamp does not illuminate, test the appropriate KR20 relay controlled output and B+ supply circuit for a short to ground or for an open/high resistance. If the circuits test normal and the 60 A fuse is OK, test or replace the appropriate KR20 cooling fan relay.
13. If all of the circuits and relays test normal, test or replace the G10 cooling fan. Replace the fuse if necessary.
Component Testing
1. Ignition OFF, disconnect the KR20 cooling fan relay.
2. Test for 70-110 ohms between terminals 85/2 and 86/1, 95-135 ohms for the KR20F relay.
• If not within the specified range, replace the KR20 cooling fan relay.
3. Measure the resistance between the terminals listed below. The DMM should display OL.
* 30/3 and 86/1
* 30/3 and 87/5
* 30/3 and 85/2
* 85/2 and 87/5
• If less than the specified range, replace the KR20 cooling fan relay.
4. Connect a 20 A fused jumper wire between relay terminal 85/2 and B+. Connect a jumper wire between relay terminal 86/1 and ground. Test for less than 2 ohms between terminals 30/3 and 87/5.
• If greater than the specified range, replace the KR20 cooling fan relay.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)
* Engine Coolant Fan Replacement (L4) Engine Coolant Fan Replacement (L4)Engine Coolant Fan Replacement (V6) Engine Coolant Fan Replacement (V6)