Electric Cooling Fan Diagnosis Functional Test
Refer to Engine Controls Schematics
Coolant Fan Motor #1 and Coolant Fan Motor #2
for a wiring diagram.
Circuit Description:
The engine cooling fans receive power from two separate 30-amp maxifuses that are located in the underhood electrical center.
During low speed operation, the PCM supplies a ground path for the Cool Fan 1 relay through the control circuit for the low speed fans. This energizes the relay coil, closes the Fan 1 relay contacts, and supplies current to the engine cooling fan #1 motor. The ground path for engine cooling fan #1 motor is through the series/parallel cooling fan relay and the engine cooling fan #2 motor. The result is a series circuit with both fans running at low speed.
In order to command the high speed cooling fan operation, the PCM first supplies a ground path for the Cool Fan 1 relay through the low speed fans control circuit. After a 3-second delay, the PCM supplies a ground path for the Cool Fan 2 and the Cool Fan 3 relays through the high speed fans control circuit. During high speed operation, current is supplied to both engine cooling fan motors through their respective maxifuses. Each fan has its own ground path.
The PCM will command the low speed cooling fans operation during any of the following conditions:
VIN K
| • | When the A/C is requested and the ambient temperature is more than 50°C (122°F). |
| • | When the engine coolant temperature exceeds 106°C (223°F). |
| • | When the A/C refrigerant pressure is more than 190 psi (2 volts). |
| • | When the ignition is off, and engine coolant temperature is more than 140°C (284°F). |
VIN 1
| • | When the A/C is requested and the ambient temperature is more than 40°C (104°F). |
| • | When the engine coolant temperature exceeds 100°C (212°F). |
| • | When the A/C refrigerant pressure is more than 190 psi (2 volts). |
| • | When the ignition is off, and the engine coolant temperature is more than 140°C (284°F). |
The PCM will command the high speed cooling fans operation during any of the following conditions:
VIN K
| • | When the engine coolant temperature exceeds 110°C (230°F). |
| • | When the A/C refrigerant pressure is more than 240 psi (2.5 volts). |
VIN 1
| • | When the engine coolant temperature exceeds 108°C (226°F). |
| • | When the A/C refrigerant pressure is more than 240 psi (2.5 volts). |
Diagnostic Aids
Inspect for the following conditions:
| • | A poor connection at the PCM, the cooling fan relays, or the cooling fan motors. Inspect the harness connectors for the following conditions: |
| - | Backed-out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly-formed terminals |
| - | Damaged terminals |
| - | Poor terminal-to-wire connections |
| • | A damaged harness--Inspect the wiring harness for damage. |
Test Description
The numbers below refer to numbers on the diagnostic table.
-
The PCM will enable the engine cooling fans when certain Diagnostic Trouble Codes are set. Go to the applicable DTC Table first, before you proceed with this table.
-
Allow the engine coolant temperature to cool to less than 100°C (212°F) before proceeding with the diagnosis.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | ||
Are any other DTCs set? | -- | |||
Are the cooling fans OFF? | 100°C (212°F) | Go to Electric Cooling Fan Diagnosis Table 1 | ||
4 | Use a scan tool in order to command the low speed cooling fan relay ON. Do both cooling fans turn ON? | -- | Go to Electric Cooling Fan Diagnosis Table 2 | |
5 | Use a scan tool in order to command the high speed cooling fan relay ON. Do both cooling fans switch to high speed? | -- | Go to Electric Cooling Fan Diagnosis Table 3 | |
6 |
Are the cooling fans ON? | -- | ||
7 | Turn ON the A/C. Are the cooling fans ON? | -- | System OK | |
8 | Does the scan tool display A/C request as YES? | -- | ||
9 |
Important: Program the replacement PCM. Refer to Powertrain Control Module Replacement/Programming Replace the PCM.Did you complete the replacement? | -- | System OK | -- |
Electric Cooling Fan Diagnosis Table #1
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Cooling Fan Functional Check? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |
2 |
Are both fans OFF? | -- | ||
3 | Disconnect the series/parallel fan relay. Are both fans OFF? | -- | ||
4 | Remove the high speed fan relay. Are both fans OFF? | -- | ||
5 |
Does the test lamp illuminate? | -- | ||
6 | Probe the series/parallel relay switch feed terminal at the right fan connector, using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
7 | Probe the series/parallel cooling fan relay control circuit at the series/parallel cooling fan relay connector, using a test lamp that is connected to B+. Does the test lamp illuminate? | -- | ||
8 |
Is the test lamp still illuminated? | -- | ||
9 | Probe the low speed cooling fan relay control circuit at the low speed cooling fan relay connector, using a test lamp that is connected to B+. Does the test lamp illuminate? | -- | ||
10 |
Is the test lamp still illuminated? | -- | ||
11 | Test the left fan feed circuit for a short to voltage, and repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct a condition? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |
12 | Repair the right fan feed circuit for a short to voltage. Refer to Wiring Repairs in Wiring System. Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
13 | Repair the short to voltage in the series/parallel relay switch feed circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
14 | Replace the low speed cooling fan relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
15 | Repair the high speed cooling fan relay control circuit, or repair the low speed cooling fan relay control circuit for a short to ground. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
16 | Replace the high speed cooling fan relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
17 | Replace the series/parallel cooling fan relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
18 |
Important:: Program the replacement PCM. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
Electric Cooling Fan Diagnosis Table #2
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Cooling Fan Functional Check? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |
2 | Did either fan turn ON when the low speed cooling fan relay was commanded ON? | -- | ||
3 | With a scan tool, command the high speed cooling fan relay ON. Did the inoperative fan from step 2 turn ON? | -- | ||
4 | Disconnect the high speed cooling fan relay. Did the inoperative fan from step 2 turn OFF? | |||
5 |
Does the test lamp illuminate? | -- | ||
6 | Probe both feed circuits at the low speed cooling fan relay connector, using a test lamp that is connected to a good ground. Does test lamp illuminate for both circuits? | -- | ||
7 |
Important: Leave the jumper in place for remainder of this table. Connect a 30-amp fused jumper wire between the switch feed circuit and the right fan feed circuit at the low speed cooling fan relay connector. Do both fans turn ON? | -- | ||
8 |
Does the test lamp illuminate? | -- | ||
9 | Connect a second 30-amp fused jumper wire between the right fan harness connector terminals. Does the left fan turn ON? | -- | ||
10 |
Does the test lamp illuminate? | -- | ||
11 | Using the second jumper wire, jumper the switch feed circuit and the left fan feed circuit together at the series/parallel relay connector. Do the fans turn ON? | -- | ||
12 |
Does the test lamp illuminate? | -- | ||
13 |
Does the test lamp illuminate? | -- | ||
14 |
Did you find a problem and did you correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |
15 |
Did you find a problem and correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
16 |
Did you find and correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |
17 | Inspect the fan motor and inspect the harness connectors for faulty terminals, and replace any problem components as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct a condition? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |
18 | Replace the fan motor. Refer to Engine Cooling Fan Replacement in Engine Cooling. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
19 | Repair the left fan feed circuit for an open. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
20 | Test the supply circuit to the inoperative fan for a short to ground, and repair the condition as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct a condition? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |
21 | Replace the fan which was not operating. Refer to Engine Cooling Fan Replacement in Engine Cooling. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
22 | Replace the high speed fan relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
23 | Repair the series/parallel fan relay switch feed circuit for a short to ground. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |
24 |
Important: If the fuse is blown, locate and repair a short to ground on the load circuit or a shorted component. Repair the open or the grounded circuit for the circuit that did not illuminate the test lamp. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
25 | Inspect the low speed fan relay and connector for faulty terminals and replace as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct a condition? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |
26 | Replace the low speed fan relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
27 | Repair the right fan feed circuit for an open. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
28 | Repair the series/parallel relay switch feed circuit for an open. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
29 | Inspect the series/parallel fan relay and connector for faulty terminals and replace as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct a condition? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |
30 | Replace the series/parallel fan relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
31 |
Important: Program the replacement PCM. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
Electric Cooling Fan Diagnosis Table #3
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Cooling Fan Functional Check? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |
2 |
Did both fans operate with no change? | -- | ||
3 | Did the right fan stop operating? | -- | ||
4 |
Does the test lamp illuminate after a few seconds? | -- | ||
5 | Probe the coil feed circuit at the high speed fan relay connector, using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
6 | Probe the switch feed circuit at the high speed fan relay connector, using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
7 | Install a 30-amp fused jumper between the high speed fan relay switch feed circuit and the left fan feed circuit at the high speed fan relay connector. Does the left fan turn ON? | -- | ||
8 |
Do the fans switch from low to high speed? | -- | ||
9 |
Does the test lamp illuminate after a few seconds? | -- | ||
10 | Probe the ground circuit at the series/parallel fan relay connector using a test lamp that is connected to B+. Does the test lamp illuminate? | -- | ||
11 | Probe the coil feed circuit at the series/parallel relay connector, using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
12 | Repair the high speed fan relay control circuit for an open between the high speed fan relay and the splice. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
13 | Repair the open in the high speed fan relay coil feed circuit . Refer to Wiring Repairs in Wiring System. Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
14 |
Important: If the fuse is blown, locate and repair a short to ground on the load circuit or on the shorted component. Repair the open in the high speed fan relay switch feed circuit . Refer to Wiring Repairs in Wiring System. Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
15 | Replace the high speed fan relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
16 | Repair the open in the left fan feed circuit between the high speed fan relay and the splice. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
17 | Repair the high speed fan relay control circuit for an open or for a short to B+. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
18 | Repair the open in the high speed fan relay control circuit between the series/parallel fan relay and the splice. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
19 | Repair the open in the ground circuit. Refer to Wiring Repairs in Wiring System. Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
20 | Replace the series/parallel fan relay. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
21 |
Important: If the fuse is blown, locate and repair the short to ground on the load circuit or on a shorted component. Repair the open in series/parallel fan relay coil feed circuit . Refer to Wiring Repairs in Wiring System. Did you complete the repair? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
22 |
Did you find and correct the condition? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | |
23 |
Important:: Program the replacement PCM. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the replacement? | -- | Go to Electric Cooling Fan Diagnosis Functional Check | -- |
