| 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
Cell 21: Engine Data Sensors-Cooling Fan Controls
Circuit Description:
During low speed operation, the engine coolant fans receive power from a 30 amp maxifuse. The PCM supplies a ground path for the Cool Fan 1 relay through the Coolant Fan #1 Relay Control circuit. This energizes the relay coil, closes the Fan 1 relay contacts, and supplies current to engine coolant fan motor #1. The ground path for cooling fan #1 is through the series/parallel cooling fan relay (Cool Fan 2 relay) and engine cooling fan motor #2. The result is a series circuit with both fans running at low speed.
During high speed fan operation, engine coolant fan motor #1 receives power from the 30 amp maxifuse. However, engine coolant fan motor #2 receives power from the 25 amp fan #3 fuse.
To command 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 (series/parallel) and Cool Fan 3 relays through the High Speed Fans Control circuit. During high speed operation, both engine coolant fans have their own ground path.
Diagnostic Aids
Check 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, and poor terminal to wire connection. |
| • | 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 applicable DTC Table first before proceeding with this table.
-
Allow engine coolant temperature to cool below 100°C (212°F) before proceeding with diagnosis.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (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 | With a scan tool, command the cooling fan relay 1 ON. Are both cooling fans ON? | -- | Go to Cooling Fan table #2 | |
5 | With a scan tool, command cooling fan relay 2 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 Functional Check for further diagnosis of the A/C system. | |
9 | Does the scan tool display A/C request as YES? | -- | Go to Functional Check for further diagnosis of the A/C Refrigerant Pressure Sensor | Go to Functional Check for further diagnosis of the A/C system. |
10 |
Important: Program the replacement PCM. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM.Is the action complete? | -- | System OK | -- |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Cooling Fan Functional Check? | -- | Go to Cooling Fan Functional Check | |
2 | Disconnect fan relay #1 Are both fans OFF? | -- | ||
3 | Disconnect fan relay #2 Are both fans OFF? | -- | ||
4 |
Does the test lamp illuminate? | -- | ||
5 | Probe terminal A of the fan 1 connector using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
6 | Probe the cooling fan high speed control circuit (473) at the cooling fan relay #2 connector location (B8) using a test lamp that is connected to B+. Does the test lamp illuminate? | -- | ||
7 |
Is the test lamp still illuminated? | -- | ||
8 | Probe the cooling fan relay low speed control circuit (335) at the cooling fan relay #1 connector location (B4) using the test lamp that is connected to B+. Does the test lamp illuminate? | -- | ||
9 |
Is the test lamp still illuminated? | -- | ||
10 | Repair the fan 2 feed circuit (504) for a short to voltage. Refer to Wiring Repairs . Did you find and correct the condition? | -- | Go to Cooling Fan Functional Check | |
11 | Repair the fan 1 feed circuit (409) for a short to voltage. Refer to Wiring Repairs . Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
12 | Repair the short to voltage in the relay #2 switch feed circuit (532). Refer to Wiring Repairs . Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
13 | Replace the cooling fan relay #1. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
14 | Repair the relay high speed control circuit (473) or the relay 1 control circuit (335) for a short to ground. Refer to Wiring Repairs . Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
15 | Replace the cooling fan relay #3. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
16 |
Important:: Program the replacement PCM. 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 | Did you perform the Cooling Fan Functional Check? | -- | Go to Cooling Fan Functional Check | |
2 | Did either fan turn ON when cooling fan relay #1 was commanded ON? | -- | ||
3 |
Did the other fan turn OFF? | -- | ||
4 | Disconnect fan relay #3. Did the fan turn OFF? | -- | ||
5 |
Does the test lamp illuminate? | -- | ||
6 | Probe both feed circuits (342 and 540) at the relay 1 connector locations (C4 and C6) using a test lamp that is connected to ground. Does test lamp illuminate for both circuits? | -- | ||
7 |
Important: Leave jumper in place for remainder of this table. Connect a fused jumper wire between the switch feed circuit (342) and the fan 1 feed circuit (409) at the relay #1 connector locations (B6 and C4). Do both fans turn ON? | -- | ||
8 |
Does the test lamp illuminate? | -- | ||
9 | Connect a second fused jumper wire between the fan harness connector terminals. Is the right fan ON? | -- | ||
10 |
Does the test lamp illuminate? | -- | ||
11 | Using the second jumper wire, jumper the switch ignition feed circuit (532) and fan 2 feed circuit (504) together at relay #2 connector locations (B9 and C8). Do the fans come ON? | -- | ||
12 |
Is the left fan ON? | -- | ||
13 |
Is the test lamp ON? | -- | ||
14 | Inspect the PCM connections. Repair faulty connections as necessary. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs . Did you find a problem and correct it? | -- | Go to Cooling Fan Functional Check | |
15 | Repair the relay low speed control circuit (335) for an open or shorted to B+. Refer to Wiring Repairs . Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
16 | Inspect the fan motor ground circuit for a open or the fan motor connections and repair as necessary. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs or Wiring Repairs . Did you find and correct the condition? | -- | Go to Cooling Fan Functional Check | |
17 | Replace the fan motor. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
18 | Repair the fan 2 feed circuit (504) for an open. Refer to Wiring Repairs . 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 #3. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
21 | Repair the relay #2 switch feed circuit (532) for a short to ground. Refer to Wiring Repairs . Did you find and correct the condition? | -- | Go to Cooling Fan Functional Check | |
22 | Repair the open or the grounded circuit for the circuit that did not light. Refer to Wiring Repairs . 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 the fan 1 feed circuit (409) for a open. Refer to Wiring Repairs . Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
25 | Repair the relay #2 switch feed circuit (532) for a open. Refer to Wiring Repairs . Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
26 | Replace fan relay #2. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
27 |
Important: Program the replacement PCM. 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 | Did you perform the Cooling Fan Functional Check? | -- | Go to Cooling Fan Functional Check | |
2 |
Did both fans operate with no change? | -- | ||
3 | Did fan 1 stop operating? | -- | ||
4 |
Does the test lamp illuminate after several seconds? | -- | ||
5 | Probe the coil feed circuit (1442) at relay #3 connector location (B4) using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
6 | Probe the switch feed circuit (1442) at the relay #3 connector location (C4) using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
7 | Jumper the switch ignition feed circuit (1442) and the fan 2 feed circuit (504) together at the relay #3 connector locations (C4 and B6). 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 (B10) using a test lamp that is connected to B+. Does the test lamp illuminate? | -- | ||
11 | Probe the coil feed circuit (540) at the relay #2 connector location (C10) using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
12 | Repair the relay high speed control circuit (473) for an open between fan relay #3 and the splice. Refer to Wiring Repairs . Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
13 | Repair the open in the relay #3 coil feed circuit (1442). Refer to Wiring Repairs . Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
14 | Repair the open in the relay #3 switch feed circuit (1442). Refer to Wiring Repairs . Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
15 | Replace the fan relay #3. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
16 | Repair the open in the fan 2 feed circuit (504) between fan relay #3 and the splice. Refer to Wiring Repairs . Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
17 | Repair the fan relay high speed control circuit (473) for an open or for a short to B+. Refer to Wiring Repairs . Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
18 | Repair the open in the fan relay high speed control circuit (473) between fan relay #2 and the splice. Refer to Wiring Repairs . Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
19 | Repair the open in the ground circuit (1050). Refer to Wiring Repairs . Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
20 | Replace the fan relay #2. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
21 | Repair the open in relay #2 coil feed circuit (540). Refer to Wiring Repairs . Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
22 |
Did you find and correct the condition? | -- | Go to Cooling Fan Functional Check | |
23 |
Important:: Program the replacement PCM. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | Go to Cooling Fan Functional Check | -- |
