LBN, LEA, LE9, or LTD
DTC P0480, P0481, P0691, P0692, P0693, or P0694 (LBN, LEA, LE9, 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.
DTC Descriptors
DTC P0480
- Cooling Fan Relay 1 Control Circuit
DTC P0481
- Cooling Fan Relays 2 and 3 Control Circuit
DTC P0691
- Cooling Fan Relay 1 Control Circuit Low Voltage
DTC P0692
- Cooling Fan Relay 1 Control Circuit High Voltage
DTC P0693
- Cooling Fan Relays 2 and 3 Control Circuit Low Voltage
DTC P0694
- Cooling Fan Relays 2 and 3 Control Circuit High Voltage
Diagnostic Fault Information
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.
Conditions for Running the DTC
* The ignition voltage is greater 11 volts.
* The ECM has commanded the output driver ON and OFF at least once during the ignition cycle.
* The DTCs run continuously when the conditions above are met.
Conditions for Setting the DTC
The commanded state of the ECM driver and the actual state of the control circuit do not match for greater than 5 seconds.
Action Taken When the DTC Sets
DTCs P0480 P0481, P0691, P0692 , P0693, and P0694 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0480 P0481, P0691, P0692 , P0693, and P0694 are Type B DTCs.
Diagnostic Aids
* The ECM has the capability of providing command to the fan relays even when a scan tool output control is being used. Always refer to the scan tool Cooling Fan Relay Command parameters to know which fans are being commanded ON by the ECM.
* 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 System Description and Operation Cooling System
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
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Engine operating, command the cooling fans ON and OFF in each of the commanded states. An audible click should be heard in each of the commanded states.
2. Observe the DTC information with a scan tool. DTC P0480 P0481, P0691, P0692 , P0693, or P0694 should not set.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Ignition OFF, disconnect the KR20 cooling fan relays listed below:
* KR20F cooling fan relay
* KR20P cooling fan medium speed relay
* KR20D cooling fan high speed relay
Note: Ignition voltage to the KR20D high speed relay coil is supplied by the KR20E speed control relay, when commanded ON.
2. Connect a test lamp between B+ and the KR20D high speed relay coil ignition circuit terminal 86/1. The test lamp should Not illuminate.
• If the test lamp illuminates, test the ignition voltage supply circuit for a short to ground.
Note: The following test must be performed on each of the relay coil ignition circuits.
3. Ignition ON, verify that a test lamp illuminates between ground and the relay coil ignition circuit terminal listed below:
* KR20F cooling fan relay terminal 85
* KR20P cooling fan medium speed relay terminal 86/1
• If the test lamp does not illuminate, test the relay coil ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay coil ignition circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.
Note: The following tests must be performed on all three fan relay control circuits.
4. Connect the red lead of the DMM to a control circuit terminal listed below. Connect the black lead to ground. Set the DMM on the diode setting. The DMM should display OL.
* KR20F cooling fan relay terminal 86
* KR20P cooling fan medium speed relay terminal 85/2
* KR20D cooling fan high speed relay terminal 85/2
• If less than the specified range, test the appropriate relay coil control circuit for a short to ground. If the circuit tests normal, replace the K20 engine control module.
Note: The following test must be performed on all three fan relay circuits.
5. Command the cooling fan relay ON and OFF with a scan tool. The DMM should transition from OL when commanded OFF to less than 1 V when commanded ON.
• If the circuit voltage does not correspond to the specified values, test the control circuit for an open/high resistance or a short to voltage. If the circuit tests normal, replace the K20 engine control module.
6. If all circuits test normal, test or replace the appropriate KR20 relay.
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 cooling fan 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)
* Control Module References Control Module References for ECM replacement, setup, and programming