Diagnostic Instructions

DTC Descriptors

DTC P0480: Cooling Fan Relay 1 Control Circuit

DTC P0481: Cooling Fan Relay 2 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 Relay 2 Control Circuit Low Voltage

DTC P0694: Cooling Fan Relay 2 Control Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Relay Coil Ignition Circuit	P0691, P0693	P0480, P0481	--	--
Relay Switch Ignition Circuit	*	*	--	--
Fan 1 Relay Control Circuit	P0691	P0480	P0692	--
Fan 2 Relay and Fan S/P Relay Control Circuit	P0693	P0481	P0694	--
Relay Controlled Output Circuit	*	*	**	--
*Fans inoperative without a DTC. **Fans always ON without a DTC.

Circuit/System Description

The engine control module (ECM) commands the fans ON in either high speed or low speed, depending on cooling requirements. In low speed, both fans are turned ON at a reduced speed. High speed has both fans turned ON at full speed.

In low speed operation, the ECM applies ground to the coil side of the low speed fan 1 relay. This energizes the coil and applies voltage directly to the right cooling fan through the switch side of the relay. The right fan is connected in series to the left cooling fan through the de-energized series/parallel (S/P) fan relay. The series circuit operates both fans at low speed.

In high speed operation, the ECM applies a ground to the coil side of the fan 1 relay, the S/P fan relay, and the high speed fan 2 relay. When energized, the fan 2 relay applies voltage directly to the left cooling fan through the switch side of the relay. Simultaneously, the fan 1 relay and the S/P fan relay provide ignition voltage and a direct path to ground for the right cooling fan. With both fans connected in a parallel circuit, each fan receives full voltage and operates at high speed.

Conditions for Running the DTC

Conditions for Setting the DTC

P0480

The ECM detects an open on the low speed cooling fan 1 relay control circuit for more than 1 second.

P0481

The ECM detects an open circuit on the high speed cooling fan 2 relay control circuit for more than 1 second.

P0691

The ECM detects a short to ground on the low speed cooling fan 1 relay control circuit for more than 1 second.

P0692

The ECM detects a short to voltage on the low speed cooling fan 1 relay control circuit for more than 1 second.

P0693

The ECM detects a short to ground on the high speed cooling fan 2 relay control circuit for more than 1 second.

P0694

The ECM detects a short to voltage on the high speed cooling fan 2 relay control circuit for more than 1 second.

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.

Reference Information

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, command the appropriate fan relay ON and OFF with a scan tool. Listen or feel the relay click.
2. 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 three cooling fan relays.

Important:  The following test 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:

•	Fan 1 and Fan 2 relays terminal 85

•	Fan S/P 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.

Important:  The following test must be performed on all three fan relay circuits.

3. Test for 2.6-4.6 volts between ground and the relay coil control circuit terminal listed below:

•	Fan 1 and Fan 2 relays terminal 86

•	Fan S/P relay terminal 85

⇒	If less than the specified range, test the relay coil control circuit for an open/high resistance or for a short to ground. If the circuit tests normal, replace the ECM.

⇒	If greater than the specified range, test the relay coil control circuit for a short to voltage. If the circuit tests normal, replace the ECM.

Important:  The following test must be performed on all three fan relay circuits.

4. Connect a test lamp between the relay coil control circuit and the relay coil ignition circuit, terminals 85 and 86.
5. Command the fan relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always OFF, replace the ECM.

6. If all circuits test normal, test or replace the relay.

Component Testing

1. Ignition OFF, disconnect the cooling fan relay.
2. Test for 70-110 ohms between terminals 85 and 86.

⇒	If the resistance is not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If not the specified range, replace the relay.

4. Test for less than 2 ohms between terminals 30 and 87A.

⇒	If greater than the specified range, replace the relay.

5. Install a 20A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87.

⇒	If greater than the specified range, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.