For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
1 | Turn ON the ignition, with the engine OFF. Does the heater water auxiliary pump operate? | Go to Step 2 | Go to Step 3
2 | Make sure the engine temperature is below 95°C (203°F). Are the auxiliary engine coolant fans and/or the electric cooling fan operating with the engine temperature below 95°C (203°F)? | Go to Step 5 | Go to Step 4
3 | The heater water auxiliary pump does not operate. Refer to Water Pump Inoperative - Electric . Does the heater water auxiliary pump operate properly? | Go to Step 31 | --
4 |

1. Connect a 5 A fused jumper between the fan control relay K26 diagnostic enable circuit and a known good ground.
2. Grounding of the fan control relay K26 diagnostic enable circuit will simulate the closing of the primary coolant fan temperature switch stage 1 contacts, this will energize the fan control relay K26.

Does the auxiliary engine coolant fan #1 and auxiliary engine coolant fan #2 operate at low speed?

Go to Step 6

Go to Step 7

5 | The auxiliary engine coolant fans and/or the electric cooling fan run with the engine temperature below 95°C (203°F) Refer to Cooling Fan Always On - Auxiliary . Are the engine cooling fans operating properly? | Go to Step 31 | --
6 | Observe the electric cooling fan. Is the electric cooling fan operating at low speed? | Go to Step 9 | Go to Step 8
7 | The auxiliary engine coolant fan #1 and auxiliary engine coolant fan #2 do not operate. Refer to Cooling Fan Inoperative - Auxiliary . Are the engine cooling fans operating properly? | Go to Step 31 | --
8 | The electric cooling fan does not operate at low speed. Refer to Cooling Fan Inoperative at Low Speed - Electric . Are the engine cooling fans operating properly? | Go to Step 31 | --
9 |

1. Turn OFF the ignition.
2. Leave all previously connected jumpers connected.

Does the water auxiliary pump operate?

Go to Step 10

Go to Step 11

10 |

1. Turn ON the ignition, with the engine OFF.
2. Leave all previously connected jumpers connected.
3. Connect a 5 A fused jumper between the fan control relay K28 and fan control relay K52 diagnostic enable circuit and a known good ground.
4. Grounding of the fan control relay K28 and fan control relay K52 diagnostic enable circuit will simulate the closing of the secondary cooling fan temperature switch, this will energize the fan control relay K28 and fan control relay K52.

Does the auxiliary engine coolant fan #1 operate at high speed?

Go to Step 12

Go to Step 13

11 | Water auxiliary pump does not operate. Refer to Auxiliary Water Pump Inoperative . Does the water auxiliary pump operate properly? | Go to Step 31 | --
12 | Observe the auxiliary engine coolant fan #2. Does the auxiliary engine coolant fan #2 operate at high speed? | Go to Step 14 | Go to Step 15
13 | The auxiliary engine coolant fan #1 does not operate at high speed. Refer to Cooling Fan Inoperative - Auxiliary . Are the engine cooling fans operating properly? | Go to Step 31 | --
14 |

1. Leave all previously connected jumpers connected.
2. Connect a 5 A fused jumper between the fan control relay K67 diagnostic enable circuit and a known good ground.
3. Grounding of the fan control relay K67 diagnostic enable circuit will simulate the closing of the primary cooling fan temperature switch stage 2 contacts, this will energize the fan control relay K67.

Does the electric cooling fan operate at high speed?

Go to Step 16

Go to Step 17

15 | The auxiliary engine coolant fan #2 does not operate at high speed. Refer to Cooling Fan Inoperative - Auxiliary . Are the engine cooling fans operating properly? | Go to Step 31 | --
16 |

1. Remove all previously connected jumpers.
2. Start the engine and allow it to run.
3. Turn the A/C compressor clutch coil ON.

Does the auxiliary engine coolant fan #1 and auxiliary engine coolant fan #2 run at low speed when the compressor clutch coil is turned ON?

Go to Step 19

Go to Step 18

17 | The electrical cooling fan does not operate at high speed. Refer to Cooling Fan Inoperative . Are the engine cooling fans operating properly? | Go to Step 31 | --
18 | The auxiliary engine coolant fan #1 and auxiliary engine coolant fan #2 do not operate when the compressor is turned ON. Refer to Cooling Fan Inoperative - Auxiliary . Are the engine cooling fans operating properly? | Go to Step 31 | --
19 |

1. Install the scan tool.
2. Monitor the engine temperature using the scan tool.
3. Remove any previously connected jumpers.
4. Turn the A/C compressor clutch coil OFF.
5. Allow the engine to run until the primary cooling fan temperature switch reaches 100°C (212°F). The stage 1 contacts should close and energize the fan control relay K26.

Does the auxiliary engine coolant fan #1 and auxiliary engine coolant fan #2 operate at low speed?

Go to Step 20

Go to Step 21

20 | Continue to allow the engine to run until the secondary cooling fan temperature switch reaches 105°C (221°F). The secondary cooling fan temperature switch should close and energize the fan control relay K28 and fan control relay K52. Does the auxiliary engine coolant fan #1 and auxiliary engine coolant fan #2 operate at high speed? | Go to Step 24 | Go to Step 25
21 | Test the control circuit of the fan control relay K26 for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 31 | Go to Step 22
22 | Test the ground circuit of the primary cooling fan temperature switch for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 31 | Go to Step 23
23 | Replace the primary cooling fan temperature switch. Refer to Engine Cooling Fan Control Switch Replacement . Did you complete the repair? | Go to Step 31 | --
24 | Continue to allow the engine to run until the primary cooling fan temperature switch reaches 110°C (230°F). The stage 2 contacts should close and energize the fan control relay K67. Does the electric cooling fan operate at high speed? | Go to Step 29 | Go to Step 27
25 | Test the control circuit of the fan control relay K28 and fan control relay K52 for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 31 | Go to Step 26
26 | Replace the secondary cooling fan temperature switch. Did you complete the repair? | Go to Step 31 | --
27 | Test the fan control relay K67 control circuit of the relay coil for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 31 | Go to Step 28
28 | Replace the primary cooling fan temperature switch. Refer to Engine Cooling Fan Control Switch Replacement . Did you complete the repair? | Go to Step 31 | --
29 |

1. Install the A/C manifold gauge set to monitor A/C refrigerant pressure.
2. Turn the A/C compressor clutch coil on.
3. Continue to operate the engine until the A/C refrigerant pressure switch reaches 275 psi.

Does the auxiliary engine coolant fan #1 and auxiliary engine coolant fan #2 operate at high speed?

Go to Step 31

Go to Step 30

30 | The auxiliary engine coolant fan #1 and auxiliary engine coolant fan #2 do not operate at high speed when the A/C refrigerant pressure switch reaches 275 psi. Refer to Cooling Fan Inoperative - Auxiliary . Are the engine cooling fans operating properly? | Go to Step 31 | --
31 | Confirm that the engine cooling fans and auxiliary water pumps operate properly . Refer to Cooling System Description . Do the engine cooling fans and auxiliary water pumps operate properly? | System OK | Go to Step 1