Schematic Reference: Engine Cooling Schematics

DEFINITION: One or both engine cooling fan motors do not operate properly in high or low speed modes.

1

Did you perform the Engine Cooling Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Engine Cooling

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, command the Fans Low Speed ON and OFF.

Do the low speed engine cooling fans turn ON and OFF with each command?

Go to Step 3

Go to Step 4

Important:: Before the PCM changes the speed of the cooling fans, a 3 second delay will occur.

With a scan tool, command the Fans High Speed ON and OFF.

Do the high speed engine cooling fans turn ON and OFF with each command?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 11

1. Remove the cooling fan 1 relay.
2. Connect a 20 A fused jumper between the battery positive voltage circuit of the cooling fan 1 relay and the cooling fan motor supply voltage circuit of the cooling fan 1 relay.

Do both cooling fans operate in low speed?

Go to Step 13

Go to Step 5

1. Leave the fused jumper wire in place of the cooling fan 1 relay.
2. Remove the cooling fan S/P relay.
3. Connect a 20 A fused jumper between the eng cool LH fan low circuit of the cooling fan S/P relay and the eng cool RH fan supply voltage circuit of the cooling fan S/P relay.

Do both cooling fans operate in low speed?

Go to Step 14

Go to Step 6

1. Leave the fused jumper wire in place of the cooling fan 1 relay.
2. Connect a 20 A fused jumper between the battery positive voltage circuit of the cooling fan S/P relay and the cooling fan motor supply voltage circuit of the cooling fan S/P relay.

Does the eng cool RH fan operate in high speed?

Go to Step 9

Go to Step 7

1. Leave the fused jumper wire in place of the cooling fan 1 relay.
2. Install the cooling fan S/P relay.
3. Disconnect the eng cool RH fan electrical connector.
4. Connect a 20 Amp fused jumper wire from the cooling fan motor supply voltage circuit of the right cooling fan electrical connector to the cooling fan motor ground circuit of the right cooling fan electrical connector.

Does the left cooling fan operate in high speed?

Go to Step 16

Go to Step 8

1. Leave the fused jumper wire in place of the cooling fan 1 relay.
2. Connect a 20 Amp fused jumper wire from the cooling fan motor supply voltage circuit of the right cooling fan electrical connector to a good ground.

Does the left cooling fan operate in high speed?

Go to Step 20

Go to Step 21

1. Leave the fused jumper wire in the cooling fan 1 relay.
2. Install the cooling fan S/P relay.
3. Disconnect the left cooling fan electrical connector.
4. Connect a 20 Amp fused jumper wire from battery positive voltage circuit of the left cooling fan electrical connector to the cooling fan motor ground circuit of the left cooling fan electrical connector.

Does the right cooling fan operate in high speed?

Go to Step 17

Go to Step 10

1. Leave the fused jumper wire in place of the cooling fan 1 relay.
2. Connect a 20 Amp fused jumper wire from battery positive voltage to the left cooling fan low circuit of the of the eng cool LH fan electrical connector.

Does the eng cool RH fan operate in high speed?

Go to Step 18

Go to Step 22

Is the right cooling fan operating properly in high speed?

Go to Step 12

Go to Step 15

1. Remove the cooling fan S/P relay
2. Connect a 20 A fused jumper between the eng cool LH fan low circuit of the cooling fan S/P relay and the ground circuit of the cooling fan S/P relay.

Does the left cooling fan operate properly in high speed?

Go to Step 14

Go to Step 19

Inspect for poor connections at the cooling fan 1 relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 23

Inspect for poor connections at the cooling fan S/P relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 24

Inspect for poor connections at the cooling fan 3 relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 25

Inspect for poor connections at the harness connector of the right cooling fan. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 26

Inspect for poor connections at the harness connector of the left cooling fan. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 28

Go to Step 27

Repair the cooling fan motor supply voltage circuit of the left cooling fan. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 28

--

Repair the cooling fan low reference circuit of the left cooling fan. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 28

--

Repair the ground circuit of the right cooling fan. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 28

--

Repair the cooling fan motor supply voltage circuit of the right cooling fan. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 28

--

Repair the cooling fan low reference circuit of the left cooling fan. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 28

--

Replace the cooling fan 1 relay.

Is the repair complete?

Go to Step 28

--

Replace the cooling fan S/P relay.

Is the repair complete?

Go to Step 28

--

Replace the cooling fan 3 relay.

Is the repair complete?

Go to Step 28

--

Replace the right cooling fan. Refer to Engine Coolant Fan Motor Replacement .

Is the repair complete?

Go to Step 28

--

Replace the left cooling fan. Refer to Engine Coolant Fan Motor Replacement .

Is the repair complete?

Go to Step 28

--

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3