w/LLT and Dual Fan
DTC P0480, P0481, P0691, P0692, P0693, or P0694 (w/LLT and Dual Fan)
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
Typical Scan Tool Data
Circuit/System Description
The engine cooling fan system consists of a cooling fan assembly containing two electric cooling fans. The engine control module (ECM) uses two fan control circuits and a series of three relays to command the fans ON in either high speed or low speed, depending on cooling requirements. To operate the fan, the ECM activates the applicable relay by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage. In low speed, both fans are turned ON at a reduced speed. High speed has both fans turned ON at full speed.
Conditions for Running the DTC
* The ignition voltage is between 10-26 volts.
* The engine speed is greater than 80 RPM.
* The ECM driver transitions from ON to OFF or from OFF to ON.
* DTC P0480, P0481, P0691, P0692, P0693, and P0694 run continuously when the conditions above are met.
Conditions for Setting the DTC
P0480
The ECM detects an open in the cooling fan relay 1 control circuit for greater than 1.5 S.
P0481
The ECM detects an open in the cooling fan relay 2 and 3 control circuit for greater than 1.5 S.
P0691
The ECM detects a short to ground in the cooling fan relay 1 control circuit for greater than 1.5 S.
P0692
The ECM detects a short to voltage in the cooling fan relay 1 control circuit for greater than 1.5 S.
P0693
The ECM detects a short to ground in the cooling fan relay 2 and 3 control circuit for greater than 1.5 S.
P0694
The ECM detects a short to voltage in the cooling fan relay 2 and 3 control circuit for greater than 1.5 S.
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 scan tool cooling fan output control operates as follows:
- Fan Relay 1 operates both fans at a low speed
- Fan Relay 2 and 3 operates one fan at a high speed
- Fan Relay 1, 2 and 3 operates the fan at a high speed
* KR20 cooling fan relay identification:
- KR20C cooling fan low speed FAN 1 Relay
- KR20D cooling fan high speed FAN 2 Relay
- KR20E cooling fan speed control FAN 3 or S/P Relay
* 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 (Connector End Views By Name)
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 (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Engine operating, observe the DTC information with a scan tool. DTC P0480, P0481, P0691, P0692, P0693, or P0694 should not set.
2. Command the cooling fans ON and OFF at high speed while observing the scan tool circuit test status parameters listed below:
* FC Relay 1 Ckt Open, Short Gnd, and Short Volts Test Status
* FC Relay 2 and 3 Ckt Open, Short Gnd, and Short Volts Test Status
The parameters should display OK or Not Run in each of the commanded states.
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 all of the KR20 cooling fan relays.
Note: The following tests must be performed on all three fan relay circuits.
2. Ignition ON, verify that a test lamp illuminates between ground and the relay coil ignition circuit terminal listed below:
* KR20C cooling fan low speed relay terminal 85
* KR20D cooling fan high speed relay terminal 85
* KR20E cooling fan speed control relay terminal 86
• 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 control circuits for the cooling fan relays are pulled-up to a voltage within the ECM, 2.6-4.6 volts on the control circuit is normal.
* The following test must be performed on all three fan relay control circuit terminals.
3. 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.
* KR20C cooling fan low speed relay terminal 86
* KR20D cooling fan high speed relay terminal 86
* KR20E cooling fan speed control relay terminal 85
• 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 ECM.
Note: The following tests must be performed on all three fan relay circuits.
4. 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 for a short to voltage. If the circuit tests normal, replace the K20 ECM.
5. 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 215-255 ohm between terminals 85 and 86.
• 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 and 86
* 30 and 87
* 30 and 85
* 85 and 87
• If less than the specified range, replace the KR20 cooling fan relay.
4. Test for less than 2 ohm between terminals 30 and 87A.
• If greater than the specified range, replace the KR20E cooling fan relay.
5. Connect a 20 A fused jumper wire between relay terminal 85 and B+. Connect a jumper wire between relay terminal 86 and ground. Test for less than 2 ohm between terminals 30 and 87.
• 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 (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming