| Table 1: | Electric Cooling Fan Functional Check |
| Table 2: | Electric Cooling Fan Table #1 |
| Table 3: | Electric Cooling Fan Table #2 |
| Table 4: | Electric Cooling Fan Table #3 |
Circuit Description:
The cooling fans are controlled by the PCM based on various inputs. Ignition voltage is supplied to all three cooling fan relay coils. The PCM controls cooling fan relay # 1 by providing the ground path. The PCM controls cooling fan relays # 2 and # 3 together by providing a ground path. The left and right cooling fans are connected in series. This will enable both fans on low speed when the fan # 1 relay is energized. When all three fan relays are energized, both fans will operate at high speed. The high speed is possible because the fan relays are wired in a parallel circuit. When the PCM detects that certain DTCs are set, the PCM will enable the cooling fans.
The PCM will enable the engine cooling fans when certain Diagnostic Trouble
Codes are set. For the Fan schematic, refer to
Fan Controls
.
Diagnostic Aids
If the owner complained of an overheating problem, it must be determined if the complaint was due to an actual boil over, or the warning indicator light, or engine coolant temperature gage indicated overheating. The gage accuracy can also be checked by comparing the Engine Coolant Temperature (ECT) sensor reading using a scan tool and comparing its reading with the gage reading.
If the engine is overheating and the cooling fans are ON, the cooling system should be checked, refer to Section 6B.
The PCM controls the low speed cooling fans in the following manner:
| • | If the vehicle is moving, the PCM will command the low speed fans ON at 108.5°C (227°F) and will command the low speed fans OFF at 104°C (219°F). |
| • | If the vehicle is at rest, the PCM will command the low speed fans ON at 104°C (219°F) and will command the low speed fans OFF at 98°C (208°F). |
The PCM controls the high speed cooling fans in the following manner:
| • | If the vehicle is moving, the PCM will command the high speed fans ON at 113°C (235°F) and will command the low speed fans OFF at 108.5°C (227°F). |
| • | If the vehicle is at rest, the PCM will command the high speed fans ON at 108.5°C (227°F) and will command the low speed fans OFF at 102.5°C (216.5°F). |
Test Description
Number(s) below refer to number(s) on the diagnostic table.
-
The PCM will enable the engine cooling fans when certain Diagnostic Trouble Codes are set. Go to applicable DTC Table first before proceeding with this table.
-
Allow engine coolant temperature to cool below 100°C (212°F) before proceeding with diagnosis diagnoses.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Powertrain OBD System Check | |
Are any DTCs set? | -- | Go to applicable DTC Table | ||
Are the cooling fans OFF? | 100°C (212°F) | Go to Cooling Fan table #1 | ||
4 | Using a scan tool, command cooling fan relay #1 ON. Are both cooling fans ON? | -- | Go to Cooling Fan table #2 | |
5 | Using a scan tool, command cooling fan relays #1, #2, #3 ON. Do both cooling fans switch to high speed? | -- | Go to Cooling Fan table #3 | |
6 |
Are the cooling fans ON? | -- | ||
7 | Turn the A/C ON. Are the cooling fans ON? | -- | System OK | |
8 | Does the scan tool display A/C request as YES? | -- | Refer to A/C Request Circuit Table for further diagnosis of the A/C system. | |
9 | Does the scan tool display A/C request as YES? | -- | Refer to DTC P0530 for further diagnosis of the A/C Refrigerant Pressure Sensor | Refer to A/C Request Circuit Table for further diagnosis of the A/C system. |
10 |
Important: Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | System OK | -- |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Cooling Fan Functional Check performed? | -- | Go to Cooling Fan Functional Check | |
2 | Disconnect fan relay #1 Are both fans OFF | -- | ||
3 | Disconnect fan relay #3 Are both fans OFF | -- | ||
4 | Using a test light connected to B+, probe cooling fan relay #3 harness connector terminal 86. Does the test light illuminate? | -- | ||
5 |
Is the test light still ON? | -- | ||
6 | Using the test light connected to B+, probe cooling fan relay #1 harness connector terminal 86. Does the test light illuminate? | -- | ||
7 |
Is the test light still ON? | -- | ||
8 | Repair circuit 409 and/or 504 for a short to B+. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
9 | Replace the cooling fan relay. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
10 | Repair circuit 473 or 335 for a short to ground. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
11 |
Important:: Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Cooling Fan Functional Check performed? | -- | Go to Cooling Fan Functional Check | |
2 | Did either fan turn ON when cooling fan relay #1 was commanded ON? | -- | ||
3 | Using a scan tool, command cooling fan relay #1 ON. Did the other fan turn OFF? | -- | ||
4 | Disconnect fan relay #2. Did the fan turn OFF? | -- | ||
5 |
Does the test light illuminate? | -- | ||
6 | With a test light connected to ground, probe fan relay #1 harness connector terminals 85 and 30. Does test light illuminate for both circuits? | -- | ||
7 |
Important: Leave jumper in place for remainder of this table. Connect a fused jumper wire between fan relay #1 harness connector terminals 30 and 87. Do both fans come ON? | -- | ||
8 |
Does the test light illuminate | -- | ||
9 | Connect a second fused jumper wire between fan harness connector terminals. Is the right fan ON | -- | ||
10 |
Is the test light ON? | -- | ||
11 | Using the second jumper wire, jumper fan relay #3 harness connector terminals 30 and 87A together. Does the fan comes ON? | -- | ||
12 |
Is the left fan ON? | -- | ||
13 |
Is the test light ON? | -- | ||
14 | Inspect the PCM connections. If connections are found to be faulty repair as necessary. Was a problem found and corrected? | -- | Go to Cooling Fan Functional Check | |
15 | Repair circuit 335 for an open or shorted to B+. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
16 | Inspect the fan motor connections and repair as necessary. Was a problem and corrected? | -- | Go to Cooling Fan Functional Check | |
17 | Replace the fan motor. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
18 | Repair open circuit 250. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
19 | Replace the fan which was not operating. Is the action complete? | -- | Go to Cooling Fan Functional Check | --
|
20 | Replace fan relay #2. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
21 | Repair circuit 532 for a shorted to ground. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
22 | Repair open or grounded circuit for the circuit that did not light. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
23 | Replace fan relay #1. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
24 | Repair open circuit 409. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
25 | Repair open circuit 532. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
26 | Replace fan relay #3. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
27 |
Important: Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Powertrain OBD System Check | |
2 |
Did both fans operate with no change? | -- | ||
3 | Did the left fan stop operating? | -- | ||
4 |
Using a scan tool, command cooling fan relay #2, #3 ON. Did the test light illuminate? | -- | ||
5 | Probe fan relay #2 harness connector terminals 85 with a test light to ground. Does the test light illuminate? | -- | ||
6 | Probe fan relay #2 harness connector terminals 30 with a test light to ground. Does the test light illuminate? | -- | ||
7 | Jumper fan relay #2 harness connector terminals 30 to 87. Is the right fan ON? | -- | ||
8 |
Do the fans switch from low to high speed? | -- | ||
9 |
Did the test light illuminate? | -- | ||
10 | Probe fan relay #3 harness connector terminals 87 with a test light to B+. Does the test light illuminate? | -- | ||
11 | Probe fan relay #3 harness connector terminals 85 with a test light to ground. Does the test light illuminate? | -- | ||
12 | Repair circuit 473 for an open between fan relay #2 and the splice. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
13 | Repair circuit 1039 for an open to fan relay #2. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
14 | Repair circuit 742 for an open to fan relay #2. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
15 | Replace the fan relay #2. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
16 | Repair open circuit 504 between fan relay #2 and the splice. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
17 | Repair circuit 473 for an open or for a short to B+. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
18 | Repair open circuit 473 between fan relay #3 and the splice. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
19 | Repair open circuit 250. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
20 | Replace the fan relay #3. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
21 | Repair open circuit 1039 to fan relay #3. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
22 |
Was a problem found and corrected? | -- | Go to Cooling Fan Functional Check | |
23 |
Important:: Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
