For 1990-2009 cars

Refer to

#### Cooling Fan Controls

Engine Controls Components
Information Sensors/Switches Description
A/C Controls
OBDII Symbol Description Notice
Handling Electrostatic Discharge Sensitive Parts Notice
.

### Circuit Description

The relay coils are energized when the PCM completes the ground path. The PCM Output Driver Module (ODM) B output 1 is grounded for Fan 1 operation.

During Fan 1 operation the PCM supplies a ground path for the Fan 1 relay through ODM B Output 1. This closes the relay contacts and current flows through the relay and to the cooling fan. The primary cooling fan is grounded at the engine block.

### Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table:

1. Stored Diagnostic Trouble Codes (That may not illuminate the Malfunction indicator Lamp) may enable the engine cooling fans. This Diagnostic Table may lead to improper diagnosis and replacement of good parts if Diagnostic Trouble Codes are present.

2. Ambient temperature must be above 9°C (48°F) before the PCM will enable the cooling fans due to A/C request. The PCM will enable the cooling fans if A/C refrigerant pressure increases regardless of ambient temperature.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Are any DTCs stored? | -- | Go to Applicable DTC | Go to Step 3
3 |

1. Engine coolant below 100°C (212°F).
2. Turn the A/C OFF.
3. Turn the ignition ON.

Is Fan 1 ON?

--

Go to Step 4

Go to Step 22

4 | Select scan tool Misc. Tests, Relay Control function and command Fan 1 ON. Is Fan 1 ON? | -- | Go to Diagnostic Aids | Go to Step 5
5 |

1. Remove Fan 1 relay.
2. Turn the ignition ON and leave the engine OFF.
3. Connect a test light between battery positive voltage and cooling fan relay control in relay harness connector.
4. Select scan tool Misc. Test, Relay Control Function and command Fan 1 ON.

Is the test light ON?

--

Go to Step 6

Go to Step 14

6 | Check for a blown fuse. Is the fuse blown? | -- | Go to Step 18 | Go to Step 7
7 |

1. Connect a test light to ground.
2. Check for battery positive voltage in Fan 1 relay harness connector.

Is the test light ON?

--

Go to Step 9

Go to Step 8

8 | Locate and repair open battery feed circuit in Fan 1 relay connector. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 29 | --
9 |

1. Turn the ignition OFF.
2. Connect a 20 Amp fused jumper between battery positive voltage and cooling fan circuit in the Fan 1 relay connector.
3. Observe Fan 1.

Is Fan 1 running?

--

Go to Step 28

Go to Step 10

10 |

1. Disconnect the Fan 1 electrical connector.
2. With the 20 Amp fused jumper between battery positive voltage and cooling fan circuit in the Fan 1 relay connector, connect a test light between Fan 1 harness connector terminals.

Is the test light ON?

--

Go to Step 27

Go to Step 11

11 |

1. Connect the test light to battery positive voltage.
2. Probe the Engine Cooling Fan Motor ground circuit at the Fan 1 connector

Is the test light ON?

--

Go to Step 12

Go to Step 13

12 | Locate and repair open in Engine Cooling Fan Motor feed circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 29 | --
13 | Locate and repair open in the Engine Cooling Fan Motor Ground circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 29 | --
14 |

1. Connect a test light to ground.
2. Probe cavity 85 at the Fan 1 relay connector.

Is the test light ON?

--

Go to Step 15

Go to Step 16

15 |

1. Turn the ignition OFF.
2. Disconnect the PCM connector.
3. Connect a test light between Battery feed and Cooling Fan relay control circuits at Fan 1 relay connector.
4. Jumper the Fan 1 relay driver circuit to ground at PCM connector.

Is the test light ON?

--

Go to Step 26

Go to Step 17

16 | Locate and repair open in the battery feed circuit to 85 in Fan 1 relay connector. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 29 | --
17 | Locate and repair open in Fan 1 relay driver circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 29 | --
18 |

1. Remove fuse to Cooling Fan relay.
2. Connect a test light to battery positive voltage.
3. Probe cavity 30 at Fan 1 Relay connector.

Is the test light ON?

--

Go to Step 19

Go to Step 20

19 | Locate and repair short to ground in battery feed circuit to cavity 30 in Fan 1 relay connector. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 29 | --
20 |

1. Disconnect Engine Cooling Fan Motor connector.
2. Connect test light to battery positive voltage.
3. Probe cavity 87 at Fan 1 relay connector.

Is test light ON?

--

Go to Step 21

Go to Step 27

21 | Locate and repair short to ground in Engine Cooling Fan Motor feed circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 29 | --
22 | Using scan tool monitor A/C pressure. Does scan tool indicate A/C pressure greater than the specified value? | 190 psi | Go to Step 23 | Go to Step 24
23 |

1. Disconnect A/C Pressure sensor.
2. Using scan tool monitor A/C pressure.

Is A/C pressure display at the specified value?

0 psi

Go to Step 25

Go to Step 26

24 | Locate and repair short to voltage in Engine Cooling Fan motor feed circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 29 | --
25 | Replace A/C Pressure sensor. Is the action complete? | -- | Go to Step 29 | --
26 | Important: : The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace PCM. Is the action complete? | -- | Go to Step 29 | --
27 | Replace Engine Cooling Fan motor. Is the action complete? | -- | Go to Step 29 | --
28 | Replace Fan 1 Relay. Is the action complete? | -- | Go to Step 29 | --
29 |

1. Engine coolant temperature less than 100°C (212°F).
2. A/C select switch OFF.
3. Turn the ignition ON.

Is Engine Cooling Fan OFF?

--

System OK

Go to Step 3