P0480
DTC P0480, P0481, P0691, P0692, P0693, or P0694
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 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. The ECM activates the applicable relay by grounding the control circuit with a solid state device called a driver. Each 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 greater than 11 volts.
* The ECM driver transitions from ON to OFF or from OFF to ON.
* DTCs P0480, P0481, P0691, P0692, P0693, and P0694 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 fan control command parameters on the scan tool 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 both fans at a low speed
- Cooling Fan Relays 2 and 3 operates one fan at a high speed
- Cooling Fan Relays 1, 2 and 3 operates both fans at a high speed
Reference Information
Schematic Reference
Engine Cooling Schematics [1][2]Cooling System
Connector End View Reference
* Component Connector End Views Fuel Pump and Level Sensor Assembly
* Electrical Center Identification Views Application and ID
Description and Operation
Cooling Fan Description and Operation Cooling Fan
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. Ignition ON.
2. Verify an audible click is heard or felt from each cooling fan relay when commanding the cooling fans ON and OFF with a scan tool.
• If a click is not heard or felt at one or more of the relays
Refer to Circuit/System Testing
• If a click is heard or felt at each of the relays
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.
4. Verify the DTC does not set.
• If the DTC sets
Refer to Circuit/System Testing
• If the DTC does not set
5. All OK.
Circuit/System Testing
1. Ignition OFF, disconnect all of the KR20 Cooling Fan Relays. Ignition ON.
Note: The following tests must be performed on all three fan relay circuits.
2. Verify that a test lamp illuminates between ground and a relay coil ignition circuit terminal listed below:
* KR20C Cooling Fan Low Speed Relay terminal 85/1
* KR20D Cooling Fan High Speed Relay terminal 86/2
* KR20E Cooling Fan Speed Control Relay terminal 86/2
• If the test lamp does not illuminate
1. Ignition OFF.
2. Test for less than 2 ohms in the ignition circuit of the appropriate KR20 Cooling Fan Relay, 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 not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the appropriate KR20 Cooling Fan Relay ignition circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance.
• If the test lamp illuminates
3. Ignition ON.
Note: The following tests must be performed on all three fan relay circuits.
4. Connect a DMM, set on the diode setting, between ground and a relay control circuit terminal listed below:
* KR20C cooling fan low speed relay terminal 86/2
* KR20D cooling fan high speed relay terminal 85/1
* KR20E cooling fan speed control relay terminal 85/1
5. Verify the DMM reading is greater than 2.5 V or displays O.L with the Cooling Fan Relays commanded OFF with a scan tool.
• If 2.5 V or less
1. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the appropriate relay coil control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K20 Engine Control Module.
• If greater than 2.5 V or displays O.L.
6. Verify the DMM reading is less than 1 V when commanding the Cooling Fan Relays ON with a scan tool.
• If 1 V or greater
1. Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module, ignition ON.
2. Test for less than 1 V between the appropriate KR20 cooling fan relay control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V.
3. Ignition OFF.
4. Test for less than 2 ohms in the appropriate KR20 Cooling Fan Relay control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 Engine Control Module.
• If less than 1 V
7. Test or replace the appropriate KR20 Cooling Fan Relay.
Component Testing
1. Ignition OFF.
2. Disconnect a KR20 Cooling Fan Relay.
3. Test for 70-110 ohms between terminals 85/2 and 86/1.
• If less than 70 ohms or greater than 110 ohms
Replace the KR20 cooling fan relay.
• If between 70-110 ohms
4. Test for infinite resistance between the following terminals:
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
OR
* 3 and 2
* 3 and 5
* 3 and 1
* 1 and 5
• If less than infinite resistance
Replace the KR20 Cooling Fan Relay.
• If infinite resistance
Note: This test only applies to the speed control relay.
5. Test for less than 2 ohms between KR20E Cooling Fan Speed Control Relay terminals 30/3 and 87A/4.
• If 2 ohms or greater
Replace the KR20E Cooling Fan Speed Control Relay.
• If less than 2 ohms
6. Install a 20 A fused jumper wire between relay terminal 85 or 2 and 12 V.
7. Install a jumper wire between relay terminal 86 or 1 and ground.
8. Test for less than 2 ohms between terminals 3/30 and 5/87.
• If 2 ohms or greater
Replace the KR20 Cooling Fan Relay.
• If less than 2 ohms
9. All OK.
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 Control Module References for ECM replacement, setup, and programming