| 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
Engine Cooling Fans
.
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 actually overheating and the gage indicated overheating, but the cooling fan is not coming ON, the Engine Coolant Temperature (ECT) sensor has probably shifted out of calibration and should be replaced.
If the engine is overheating and the cooling fans are ON, the cooling system should be checked, refer to Section 6B.
The PCM will command low speed fans ON at 108°C (226°F) and OFF at 105°C (221°F) and, high speed fans ON at 112°C (234°F) and OFF at 109°C (229°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? | -- | ||
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 the cooling fan relay #1 ON. Are both the cooling fans ON? | -- | Go to Cooling Fan table #2 | |
5 | Using a scan tool, command cooling fan relays #1, #2, #3 ON. Do both the 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? | -- | Go to Air Conditioning (A/C) Request Circuit Check for further diagnosis. | |
9 | Does the scan tool display A/C request as YES? | -- | Go to DTC P0530 Air Conditioning (A/C) Refrigerant Pressure Sensor Circuit for further diagnosis of the A/C Refrigerant Pressure Sensor | Go to Air Conditioning (A/C) Request Circuit Check for further diagnosis. |
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 J2. 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 D2. 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 D5 and D1. Does test light illuminate for both circuits? | -- | ||
7 | Connect a fused jumper wire between fan relay #1 harness connector terminals D1 and D4. (Leave jumper in place for remainder of this table.) 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 J4 and J3 together. Does the fan come 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 150. 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 Cooling Fan Functional Check performed? | -- | Go to Cooling Fan Functional 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 and #3 ON. Did the test light illuminate? | -- | ||
5 | Probe fan relay #2 harness connector Terminal F2 with a test light to ground. Does the test light illuminate? | -- | ||
6 | Probe fan relay #2 harness connector terminal F4 with a test light to ground. Does the test light illuminate? | -- | ||
7 | Jumper fan relay #2 harness connector terminals F4 to F1. 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 terminal J1 with a test light to B+. Does the test light illuminate? | -- | ||
11 | Probe fan relay #3 harness connector Terminal J5 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 1440 for an open to fan relay #2. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
14 | Repair circuit 402 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 150. 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 1440 to fan relay #3. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
22 | 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 | |
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 | -- |
