For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Engine Cooling Schematics Connector End View Reference: Cooling System Connector End Views DEFINITION: One or both cooling fan motors are inoperative in either high/low speed or both speeds.
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Install a scan tool.
2. Turn the ignition switch ON, 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

3 | Important: A 3 second delay occurs before the powertrain control module (PCM) changes the cooling fan speed. 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 | Go to Step 6
4 |

Important: Do not remove the connected jumper wire until your testing is completed. If the low speed fan fuse opens when you connect the jumper wire, repair the cooling fan motor supply voltage circuit of the right cooling fan motor for a short to ground.

1. Disconnect the low speed fan relay.
2. Connect a jumper wire between the battery positive voltage circuit and the cooling fan motor supply voltage circuit of the low speed fan relay.

Do both cooling fans operate in low speed?

Go to Step 14

Go to Step 5

5 |

1. Disconnect the S/P fan relay.
2. With a test lamp connected to a good ground, probe the cooling fan low reference circuit at the S/P fan relay.

Does the test lamp illuminate?

Go to Step 9

Go to Step 8

6 | Does the right cooling fan operate at high speed? | Go to Step 16 | Go to Step 7
7 | Inspect the ground circuit of the S/P fan relay for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the problem? | Go to Step 25 | Go to Step 15
8 |

1. Install the S/P fan relay.
2. Disconnect the right cooling fan electrical connector.
3. With a test lamp connected to a good ground, probe the cooling fan motor supply voltage circuit at the right cooling fan motor connector.

Does the test lamp illuminate?

Go to Step 12

Go to Step 13

9 |

1. Install the S/P fan relay.
2. Disconnect the left cooling fan motor connector.
3. With a test lamp connected to a good ground, probe the cooling fan motor supply voltage circuit at the left cooling fan connector.

Does the test lamp illuminate?

Go to Step 11

Go to Step 10

10 | Inspect the cooling fan motor supply voltage circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the problem? | Go to Step 25 | Go to Step 15
11 | Inspect the ground circuit of the left cooling fan for an open or high resistance. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the problem? | Go to Step 25 | Go to Step 18
12 | Inspect the cooling fan low reference circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the problem? | Go to Step 25 | Go to Step 17
13 | Inspect the cooling fan motor supply voltage circuit of the right cooling fan for an open or high resistance. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the problem? | Go to Step 25 | Go to Step 19
14 | Inspect the low speed cooling fan relay for poor connections. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the problem? | Go to Step 25 | Go to Step 20
15 | Inspect for poor connections at the S/P fan relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the problem? | Go to Step 25 | Go to Step 21
16 | Inspect the high speed cooling fan relay for poor connections. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the problem? | Go to Step 25 | Go to Step 22
17 | Inspect the harness connector of the right cooling fan for poor connections. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the problem? | Go to Step 25 | Go to Step 23
18 | Inspect the harness connector of the left cooling fan for poor connections. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the problem? | Go to Step 25 | Go to Step 24
19 | Repair the battery positive voltage circuit for an open or high resistance. Refer to Wiring Repairs . Did you complete the repairs? | Go to Step 25 | --
20 | Replace the low speed fan relay. Did you complete the replacement? | Go to Step 25 | --
21 | Replace the S/P fan relay. Did you complete the replacement? | Go to Step 25 | --
22 | Replace the high speed fan relay. Did you complete the replacement? | Go to Step 25 | --
23 | Replace the right cooling fan. Refer to Fan Replacement . Did you complete the replacement? | Go to Step 25 | --
24 | Replace the left cooling fan. Refer to Fan Replacement . Did you complete the replacement? | Go to Step 25 | --
25 | Operate the system in order to verify the repairs. Did you correct the problem? | System OK | Go to Step 3