Cooling Fan Always On Dual Fan

The engine control module (ECM) grounds the K2 relay, the K10 relay, and the K11 relay control circuits through an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line that is monitored by the ECM. When the ECM is commanding a component ON, the voltage potential of the control circuit should be low, near 0 volts. When the ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high, near battery voltage. If the ECM detects that the actual state of the control circuit does not match the expected state, a DTC will set.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Description and Operation

Cooling Fan 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

1. If DTCs P0691, P0692, P0693 or P0694 are set, then perform those diagnostics first.
2. Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
3. Ignition ON, observe that the fan is not activated.

Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, disconnect the relays.
2. Ignition ON, observe that the fans are not activated.

⇒	If the fans are not activated, replace the faulty relay.

⇒	If a fan is activated, test the fan voltage supply circuits for a short to voltage.

1. Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
2. Ignition ON, observe that the fan is not activated.

Cooling Fan Always On Single Fan

The engine control module (ECM) grounds the relay control circuits through an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line that is monitored by the ECM. When the ECM is commanding a component ON, the voltage potential of the control circuit should be low, near 0 volts. When the ECM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high, near battery voltage. If the ECM detects that the actual state of the control circuit does not match the expected state, a DTC will set.

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Description and Operation

Cooling Fan 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

1. If DTCs P0691, P0692, P0693 and P0694 are set, perform those diagnostics first.
2. Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
3. Ignition ON, observe that the fan is not activated.

Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, disconnect the appropriate relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.

⇒	If the test lamp illuminates, test the control circuit for a short to voltage.

3. Verify that a test lamp illuminates between the ignition circuit terminal 30 and ground.

⇒

If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the appropriate relay.

4. Verify that a test lamp illuminates between the ignition circuit terminal 86 and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for an open/high resistance.

5. Disconnect the harness connector at the cooling fan.
6. Test for less than 1 ohm between the cooling fan ground circuit terminal 1 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

7. Connect the harness connector at the cooling fan.
8. Connect a 20A fused jumper wire between the ignition circuit terminal 30 and the control circuit terminal 87. Verify the cooling fan is activated.

⇒	If the cooling fan does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the cooling fan.

9. Connect a test lamp between the ignition circuit terminal 86 and the control circuit terminal 85.
10. Clear the DTCs with a scan tool.
11. Command the appropriate 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 ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.

⇒	If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

12. If all circuits test normal, test or replace the appropriate relay.

Relay Test

1. Ignition OFF, disconnect the appropriate relay.
2. Test for 75-90 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 value, replace the relay.

4. Test for less than 1 ohm between terminals 30 and 87A.

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

5. Install a 5A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 1 ohm between terminals 30 and 87.

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

1. Ignition ON, verify with a scan tool that the ECM is not commanding fan activation.
2. Ignition ON, observe that the fan is not activated.