Schematic Reference: Engine Cooling Schematics

Connector End View Reference: Cooling System Connector End Views

DEFINITION: One or both engine coolfan 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 Fan Relay 1 ON and OFF.

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

Go to Step 3

Go to Step 4

With a scan tool, command the Fan Relays 1, 2 & 3 ON and OFF.

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

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

Go to Step 11

Important: Do NOT remove the 20-A fused jumper wire connected during this step. Use a second 20-A fused jumper wire while performing the following steps.

1. Disconnect the coolfan 1 relay.
2. Connect the first 20-A fused jumper between the battery positive voltage circuit of the coolfan 1 relay and the coolfan motor supply voltage circuit of the coolfan 1 relay.

Do both coolfans operate in low speed?

Go to Step 13

Go to Step 5

1. Disconnect the coolfan 3 relay.
2. Connect the second 20-A fused jumper between the left coolfan circuit of the coolfan 3 relay and the right coolfan motor supply voltage circuit of the coolfan 3 relay.

Do both coolfans operate in low speed?

Go to Step 14

Go to Step 6

Connect the second 20-A fused jumper from the battery positive voltage to the coolfan motor supply voltage circuit of the coolfan 3 relay.

Does the right coolfan operate in high speed?

Go to Step 9

Go to Step 7

1. Install the coolfan 3 relay.
2. Disconnect the right coolfan electrical connector.
3. Connect the second 20-Amp fused jumper wire from the coolfan motor supply voltage circuit of the right electrical connector to the coolfan ground circuit of the right electrical connector.

Does the left coolfan operate in high speed?

Go to Step 16

Go to Step 8

Connect the second 20-Amp fused jumper wire from the coolfan supply voltage circuit of the right coolfan electrical connector to a good ground.

Does the left coolfan motor operate in high speed?

Go to Step 20

Go to Step 21

1. Install the coolfan 3 relay.
2. Disconnect the left coolfan electrical connector.
3. Connect the second 20-Amp fused jumper from the coolfan motor supply voltage circuit of the left coolfan electrical connector to the low reference circuit of the left coolfan electrical connector.

Does the right coolfan motor operate in high speed?

Go to Step 17

Go to Step 10

Connect the second 20-Amp fused jumper wire from battery positive voltage to the left coolfan low reference circuit of the left coolfan electrical connector.

Does the right coolfan operate in high speed?

Go to Step 18

Go to Step 22

Does the right coolfan operate in high speed?

Go to Step 12

Go to Step 15

1. Disconnect the coolfan 3 relay.
2. Connect a 20-A fused jumper between the left coolfan low reference circuit of the coolfan 3 relay and the ground circuit of the coolfan 3 relay.

Does the left coolfan operate properly in high speed?

Go to Step 14

Go to Step 19

Inspect for poor connections at the coolfan 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 coolfan 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 24

Inspect for poor connections at the coolfan 2 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 coolfan. 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 coolfan. 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 left coolfan motor supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 28

--

Repair the left coolfan ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 28

--

Repair the right coolfan ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 28

--

Repair the right coolfan motor supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 28

--

Repair the left coolfan low reference circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 28

--

Replace the coolfan 1 relay.

Is the repair complete?

Go to Step 28

--

Replace the coolfan 3 relay.

Is the repair complete?

Go to Step 28

--

Replace the coolfan 2 relay.

Is the repair complete?

Go to Step 28

--

Replace the right coolfan. Refer to Engine Coolant Fan Motor Replacement .

Is the repair complete?

Go to Step 28

--

Replace the left coolfan. 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