Service Information

Cruze

DTC P0480 or P0481

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0480 00: Cooling Fan Relay 1 Control Circuit

DTC P0481 00: Cooling Fan Relay 2 Control Circuit

Diagnostic Fault Information

KR20A Cooling Fan Medium Speed 1 Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Ignition Circuit	-	P0480 00, P0481 00	-	-
Ignition Switch Circuit	1	2	-	-
Control Circuit	-	P0481 00	-	-
Control Output Circuit	1	2	3	-
Low and medium speed fan inoperative without a DTC. Medium speed fan inoperative without a DTC. Medium speed fan always ON without a DTC.

KR20B Cooling Fan Medium Speed 2 Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Ignition Circuit	-	2	-	-
Ignition Switch Circuit	1	2	-	-
Control Fan Circuit	3	2	4	-
Control Output Circuit	1	2	3	-
Low and medium speed fan inoperative without a DTC Low speed fan inoperative without a DTC. Low speed fan always ON without a DTC. Low and high speed fan inoperative without a DTC.

KR20D Cooling Fan High Speed Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Ignition Circuit	-	P0481 00	1	-
Ignition Switch Circuit	2	2	-	-
Control Fan Circuit	-	P0481 00	-	-
Control Output Circuit	2	2	3	-
Medium speed fan replaced by high speed fan without a DTC. High speed fan inoperative without a DTC. High speed fan always ON without a DTC.

KR20E Cooling Fan Speed Control Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Ignition Circuit	-	1	-	-
Ignition Switch Circuit	-	1	-	-
Control Fan Circuit	2	1	3	-
Control Output Circuit	-	1	4	-
High speed fan inoperative without a DTC. Low speed fan always ON without a DTC. Low and high speed fan inoperative without a DTC. High speed fan inoperative without a DTC.

KR20F Cooling Fan Relay

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Ignition Circuit	-	P0480 00	-	-
Ignition Switch Circuit	-	1	2	-
Control Fan Circuit	-	P0480 00	-	-
Control Output Circuit	-	2	2	-
Low speed fan always ON without a DTC and, if commanded, medium speed fan replace by high speed fan without a DTC. Low speed fan and high speed fan inoperative without a DTC.

The engine control module (ECM) commands the fan ON in either high speed, medium speed, or low speed, depending on cooling requirements. In low speed, the fan is turned ON at a reduced speed. In medium speed, the fan is turned ON at a higher reduced speed. In high speed, the fan is turned ON at full speed.

In low speed operation, the ECM provides ground from ECM terminal X2 67 to the cooling fan relay. The cooling fan relay activates and provides ground to the coils of the cooling fan medium speed 2 relay and the cooling fan speed control relay. The cooling fan speed control relay activates and provides power to the coil of the cooling fan high speed relay. The cooling fan high speed relay remains inactive because ECM terminal X2 66 is not grounded. The cooling fan medium speed 2 relay provides power to the cooling fan motor through cooling fan terminal 2 and the internal fan resistor.

In medium speed operation, the ECM provides ground from ECM terminal X2 66 to the cooling fan high speed relay and the cooling fan medium speed 1 relay. The cooling fan high speed relay remains inactive because power is not provided to the coil from the cooling fan speed control relay. The cooling fan medium speed 1 relay activates and provides power to the cooling fan motor through cooling fan terminal 3 and the internal fan resistor.

In high speed operation, the ECM provides ground from ECM terminals X2 66 and X2 67. As previously described, power is now provided to both cooling fan terminals 2 and 3. In addition, power and ground are now provided to the coil of the cooling fan high speed relay. The cooling fan high speed relay activates and provides power to the cooling fan motor through cooling fan terminal 4, bypassing the internal fan resistors.

Conditions for Running the DTC

•	The engine is running.

•	The ignition voltage is between 11-16 V.

•	The ECM driver transitions from ON to OFF or from OFF to ON.

Conditions for Setting the DTC

P0480 00

The ECM detects an open, short to ground, or short to voltage on the low speed cooling fan relay control circuit for more than 0.5 s.

P0481 00

The ECM detects an open, short to ground, or short to voltage circuit on the high speed cooling fan relay control circuit for more than 0.5 s.

Action Taken When the DTC Sets

•	DTCs P0480 00 and P0481 00 are Type B DTCs.

•	The service vehicle soon indicator will illuminate.

Conditions for Clearing the DTC

DTCs P0480 00, P0481 00, P0691 00, P0692 00, P0693 00, and P0694 00 are Type B DTCs.

Reference Information

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, command the Cooling Fan Relay 1 ON and OFF with a scan tool. You should hear the KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, and KR20B Cooling Fan Medium Speed 2 Relay click when commanded ON and OFF.
Command the Cooling Fan Relay 2 ON and OFF with a scan tool. You should hear the KR20A Cooling Fan Medium Speed 1 Relay click when commanded ON and OFF.
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

Ignition OFF, disconnect the KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, KR20A Cooling Fan Medium Speed 1 Relay, or KR20B Cooling Fan Medium Speed 2 Relay.
Ignition ON, verify that a test lamp illuminates between the KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, KR20B Cooling Fan Medium Speed 2 Relay coil ignition circuit terminal 85 and ground, or KR20A Cooling Fan Medium Speed 1 Relay coil ignition circuit terminal 3 and ground.

⇒

If the test lamp does not illuminate, test the KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, KR20A Cooling Fan Medium Speed 1 Relay, or KR20B Cooling Fan Medium Speed 2 Relay coil ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, KR20A Cooling Fan Medium Speed 1 Relay, or KR20B Cooling Fan Medium Speed 2 Relay coil ignition circuit fuses F42, F45, or F46 for an open, test all components connected to the ignition circuit and repair and replace as necessary.

Connect a test lamp between the KR20F Cooling Fan Relay, KR20D Cooling Fan High Speed Relay coil control circuit terminal 86 and B+, or KR20A Cooling Fan Medium Speed 1 Relay coil control circuit terminal 2 and B+.
Command the Cooling Fan Relay 1 Command, or Cooling Fan Relay 2 Command ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states for the appropriate relay.

⇒	If the test lamp is always ON, test the KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, KR20A Cooling Fan Medium Speed 1 Relay coil control circuit for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module.

⇒	If the test lamp is always OFF, test the relay coil control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

If all circuits test normal, test or replace the KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, KR20A Cooling Fan Medium Speed 1 Relay, or KR20B Cooling Fan Medium Speed 2 Relay.

Component Testing

Relay Test

Ignition OFF, disconnect the KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, KR20A Cooling Fan Medium Speed Relay, or KR20B Cooling Fan Medium Speed 2 Relay.
Measure for 70-110 Ω between terminals 85 and 86 of the KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, KR20B Cooling Fan Medium Speed 2 Relay, or terminals 1 and 2 of the KR20A Cooling Fan Medium Speed 1 Relay.

⇒	If the resistance is not within the specified range, replace the appropriate KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, KR20A Cooling Fan Medium Speed 1 Relay, or KR20B Cooling Fan Medium Speed 2 Relay.

Measure for infinite resistance between following terminals of the appropriate KR20F Cooling Fan Relay, KR20D Cooling Fan High Speed Relay, KR20B Cooling Fan Medium Speed 2 Relay, or KR20A Cooling Fan Medium Speed 1 Relay:

•	Terminals 30 and 86 KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, and KR20B Cooling Fan Medium Speed 2 Relay

•	Terminals 30 and 87 KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, and KR20B Cooling Fan Medium Speed 2 Relay

•	Terminals 30 and 85 KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, and KR20B Cooling Fan Medium Speed 2 Relay

•	Terminals 85 and 87 KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, and KR20B Cooling Fan Medium Speed 2 Relay

•	Terminals 3 and 2 KR20A Cooling Fan Medium Speed 1 Relay

•	Terminals 3 and 5 KR20A Cooling Fan Medium Speed 1 Relay

•	Terminals 3 and 1 KR20A Cooling Fan Medium Speed 1 Relay

•	Terminals 1 and 5 KR20A Cooling Fan Medium Speed 1 Relay

⇒	If continuity is detected, replace the appropriate KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, KR20A Cooling Fan Medium Speed 1 Relay, or KR20B Cooling Fan Medium Speed 2 Relay.

Connect a 20 A fused jumper wire from the positive terminal of the battery to the appropriate KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, KR20B Cooling Fan Medium Speed 2 Relay, terminal 85 or KR20A Cooling Fan Medium Speed 1 Relay. Connect a jumper wire from the negative terminal of the battery to KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, and KR20B Cooling Fan Medium Speed 2 Relay, terminal 86 or KR20A Cooling Fan Medium Speed 1 Relay terminal 2. Measure for less than 5 Ω between KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, and KR20B Cooling Fan Medium Speed 2 Relay terminal 30 and terminal 87 or KR20A Cooling Fan Medium Speed 1 Relay terminal 3 and terminal 5.

⇒	If the resistance measures more than 5 Ω, replace the appropriate KR20F Cooling Fan Relay, KR20E Cooling Fan Speed Control Relay, KR20D Cooling Fan High Speed Relay, KR20A Cooling Fan Medium Speed 1 Relay, or KR20B Cooling Fan Medium Speed 2 Relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Relay Replacement

•	Control Module References for Engine Control Module replacement, setup, and programming