| 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 |
Refer to
RH and LH Cooling Fans
.
Circuit Description
Power for the fan motors is supplied through the underhood accessory wiring junction block. The cooling fan relays are energized when current flows from the fan control 1 fuse and fan 2 and 3 control fuse in the underhood accessory wiring junction block through the relay coils to ground through the Powertrain Control Module (PCM). The low speed fans control circuit is grounded for low speed fans operation. The low speed fans control circuit and the high speed fans control circuits are all grounded for high speed fans operation.
During low speed fans operation the PCM supplies a ground path for the cool fan 1 relay. This closes cool fan 1 relay contacts, allowing current to flow from the underhood accessory wiring junction block through the relay contacts to the right hand cooling fan motor. During low speed operation, the ground path for the right hand cooling fan motor is through the cool fan 2 relay and the left hand engine cooling fan motor. The result is a series circuit with both cooling fans running at low speed.
During high speed cooling fan operation the PCM supplies a ground path for the cool fan 1 relay. The PCM also supplies a ground path for cool fan 2 and cool fan 3 relays. This closes all three cooling fan relays. During high speed fans operation, both the right and the left hand engine cooling fans are supplied current from the underhood accessory wiring junction block and each cooling fan has its own ground path.
Diagnostic Aids
If the owner complained of an overheating problem, determine if the complaint was due to an actual boil over, the warning indicator illuminated, or the engine coolant temperature (ECT) gauge indicated overheating. The gauge accuracy can also be checked by comparing the ECT sensor reading using a scan tool and comparing its reading with the gauge reading. If the engine is actually overheating and the gauge indicated overheating, but the cooling fans are not turning on, the ECT sensor may have shifted out of calibration and should be replaced. If the engine is overheating and the cooling fans are on, the cooling system is suspect and should be checked.
Inspect for the following conditions:
| • | Poor connection at the PCM, cooling fan relays, or cooling fan motors--Inspect harness connectors for: |
| - | Backed out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| - | Poor terminal to wire connection |
| • | Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. |
| • | Damaged harness--Inspect the wiring harness for damage. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. |
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 (DTCs) are set. Refer to the applicable DTC table first before proceeding with this table.
-
Allow the engine coolant temperature to cool below 100°C (212°F) before proceeding with diagnosis.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Are any DTCs set? | -- | Go to the applicable DTC table | ||
Are the cooling fans OFF? | 100°C (212°F) | Go to Cooling Fan table #1 | ||
4 | With a scan tool, command Low Speed Fans ON. Are both cooling fans ON? | -- | Go to Cooling Fan table #2 | |
5 |
Important: Allow a 3-5 second delay before determining if the fans have switched from low to high speed. With a scan tool, command High Speed Fans ON. Do both cooling fans switch to high speed? | -- | Go to Cooling Fan 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? | -- | Go to VDOT Air Conditioning (A/C) System Diagnosis in HVAC | |
9 | Does the scan tool display A/C request as YES? | -- | Go to Powertrain Control Module Controlled Air Conditioning (A/C) Circuit Diagnosis | Go to VDOT Air Conditioning (A/C) System Diagnosis in HVAC |
10 |
Important : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .Is the action complete? | -- | System OK | -- |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Cooling Fan Functional Check? | -- | Go to Cooling Fan Functional Check | |
2 | Disconnect cool fan 1 relay. Are both fans OFF? | -- | ||
3 | Disconnect cool fan 2 relay. Are both fans OFF? | -- | ||
4 |
Does the test lamp illuminate? | -- | ||
5 | Probe terminal A of the left fan connector using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
6 | Probe the high speed fans control circuit (473) at the cool fan 2 relay connector location (85) using a test lamp that is connected to battery positive voltage. Does the test lamp illuminate? | -- | ||
7 |
Is the test lamp still illuminated? | -- | ||
8 | Probe the low speed fans control circuit (335) at the cool fan 1 relay connector location (85) using the test lamp that is connected to battery positive voltage. Does the test lamp illuminate? | -- | ||
9 |
Is the test lamp still illuminated? | -- | ||
10 | Repair the RH fan feed circuit (504) for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Cooling Fan Functional Check | |
11 | Repair the LH fan feed circuit (409) for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
12 | Repair the short to voltage in the cool fan 2 relay switch feed circuit (532). Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
13 | Replace the cool fan 1 relay. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
14 | Repair the high speed fans control circuit (473) or the low speed fans control circuit (335) for a short to ground. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
15 | Replace the cool fan 3 relay. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
16 |
Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Cooling Fan Functional Check? | -- | Go to Electric Cooling Fan Functional Check | |||||||
2 | Did either fan turn ON when the Low Speed Fans were commanded ON? | -- | ||||||||
3 |
Did the Left fan turn OFF? | -- | ||||||||
4 |
Does the test lamp illuminate? | -- | ||||||||
5 | Probe both feed circuits at the relay #1 connector locations (86 and 87) using a test lamp that is connected to a good ground. Does test lamp illuminate for both circuits? | -- | ||||||||
6 |
Important: Leave jumper in place for remainder of this table. Connect a fused jumper wire between the #1 relay switch feed circuit and the LH fan feed circuit (409) at the relay #1 connector locations (87 and 30). Do both fans turn ON? | -- | ||||||||
7 |
Does the test lamp illuminate? | -- | ||||||||
8 | Connect a second fused jumper wire between the fan harness connector terminals. Is the right fan ON? | -- | ||||||||
9 |
Does the test lamp illuminate? | -- | ||||||||
10 | Using a second jumper wire, jumper the switch ignition feed circuit (532) and the RH fan feed circuit (504) together at relay #2 connector locations (30 and 87A). Do the fans come ON? | -- | ||||||||
11 |
Is the left fan ON? | -- | ||||||||
12 |
Is the test lamp illuminated? | -- | ||||||||
13 | Inspect the fan motor ground circuit for a open or the fan motor connections and repair as necessary. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs or Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Electric Cooling Fan Functional Check | |||||||
14 |
Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- | ||||||
15 | Repair the RH fan feed circuit (504) for an open or short to ground and replace fuse if necessary.Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | |||||||
16 | Replace fan relay #3. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- | ||||||
17 | Repair the relay #2 switch feed circuit (532) for a short to ground. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Electric Cooling Fan Functional Check | |||||||
18 | Replace the fan motor. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- | ||||||
19 | Replace fan relay #1. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- | ||||||
20 | Repair the LH fan feed circuit (409) for a open. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- | ||||||
21 | Repair the relay #2 switch feed circuit (532) for a open. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- | ||||||
22 | Replace fan relay #2. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Cooling Fan Functional Check? | -- | Go to Electric Cooling Fan Functional Check | |
2 |
Did both fans operate with no change? | -- | ||
3 | Did the left fan stop operating? | -- | ||
4 |
Does the test lamp illuminate after several seconds? | -- | ||
5 | Probe the coil feed circuit at relay #3 connector location (85) using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
6 | Probe the switch feed circuit (2140) at the relay #3 connector location (30) using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
7 | Jumper the switch ignition feed circuit (2140) and the RH fan feed circuit (504) together at the relay #3 connector locations (30 and 87). Is the right fan ON? | -- | ||
8 |
Do the fans switch from low to high speed? | -- | ||
9 |
Does the test lamp illuminate? | -- | ||
10 | Probe the ground circuit (1050) at the relay #2 connector location (87) using a test lamp that is connected to B+. Does the test lamp illuminate? | -- | ||
11 | Probe the coil feed circuit at the relay #2 connector location (86) using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
12 | Repair the relay 2 and 3 control circuit (473) for an open between fan relay #3 and the splice or replace the underhood wiring electrical center.Refer to Wiring Repairs in Wiring Systems or Underhood Electrical Center or Junction Block Replacement in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
13 | Repair the open in the relay #3 coil feed circuit or replace the underhood wiring electrical center. Refer to Wiring Repairs in Wiring Systems or Underhood Electrical Center or Junction Block Replacement in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
14 | Repair the open or short to ground in the relay #3 switch feed circuit (2140) or replace the underhood wiring electrical center. Refer to Wiring Repairs in Wiring Systems or Underhood Electrical Center or Junction Block Replacement in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
15 | Replace the fan relay #3. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
16 | Repair the open in the RH fan feed circuit (504) between fan relay #3 and the splice or replace the underhood wiring electrical center. Refer to Wiring Repairs in Wiring Systems or Underhood Electrical Center or Junction Block Replacement in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
17 | Repair the fan 2 and 3 relay control circuit (473) for an open or for a short to B+ or replace the underhood wiring electrical center.Refer to Wiring Repairs in Wiring Systems or Underhood Electrical Center or Junction Block Replacement in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
18 | Repair the open in the fan 2 and 3 relay control circuit (473) between fan relay #2 and the splice or replace the underhood wiring electrical center.Refer to Wiring Repairs in Wiring Systems or Underhood Electrical Center or Junction Block Replacement in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
19 | Repair the open in the ground circuit (1050). Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
20 | Replace the fan relay #2. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
21 | Repair the open in relay #2 coil feed circuit or replace the underhood wiring electrical center.Refer to Wiring Repairs in Wiring Systems or Underhood Electrical Center or Junction Block Replacement in Wiring Systems. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
22 |
Did you find and correct the condition? | -- | Go to Electric Cooling Fan Functional Check | |
23 |
Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the repair? | -- | Go to Electric Cooling Fan Functional Check | -- |
