锟斤拷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.
4. Command the appropriate 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.
锟斤拷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 70-110 ohm between terminals 85 and 86.
锟斤拷If not within the specified range, replace the KR20 cooling fan relay.
3. Measure the resistance between the terminals listed below:
* 30 and 86
* 30 and 87
* 30 and 85
* 85 and 87
The DMM should display OL.
锟斤拷If less than the specified range, replace the KR20 cooling fan relay.
4. Test the KR20 Fan Control Relay for less than 2 ohm between terminals 30 and 87A.
锟斤拷If greater than the specified range, replace the fan control 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.
锟斤拷If greater than the specified range, replace the KR20 cooling fan relay.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Relay Replacement (Attached to Wire Harness) (See: Power and Ground Distribution/Power Distribution Relay/Service and Repair/Relay
Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (See: Power and Ground Distribution/Power
Distribution Relay/Service and Repair/Relay Replacement (Within an Electrical Center))
* Underhood Electrical Center or Junction Block Replacement (See: Maintenance/Fuses and Circuit Breakers/Fuse Block/Service and
Repair/Removal and Replacement/Underhood Electrical Center or Junction Block Replacement)
* Engine Coolant Fan Replacement (HP2) (See: Engine, Cooling and Exhaust/Cooling System/Radiator Cooling Fan/Service and
Repair/Engine Coolant Fan Replacement)Engine Coolant Fan Replacement (Non-HP2) (See: Engine, Cooling and Exhaust/Cooling
System/Radiator Cooling Fan/Service and Repair/Engine Coolant Fan Replacement)
* Control Module References (See: Testing and Inspection/Programming and Relearning)for ECM replacement, setup, and programming
P0481
DTC P0480 or P0481 (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0480
- Cooling Fan Relay 1 Control Circuit
