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 |
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 the fan 2 and 3 control fuse in the underhood accessory 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 junction block through the relay contacts to the right cooling fan motor. During low speed operation, the ground path for the right cooling fan motor is through the cool fan 2 relay and the left 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 3 cooling fan relays. During high speed fans operation, both the right and the left engine cooling fans are supplied current from the underhood accessory junction block and each cooling fan has a ground path.
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:
• | A poor connection at the PCM, the cooling fan relays, or the cooling fan motors. Inspect the harness connectors for the following conditions. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems: |
- | Backed-out terminals |
- | Improper mating |
- | Broken locks |
- | Improperly formed or damaged terminals |
- | Poor terminal-to-wire connections |
• | A damaged harness. Inspect the wiring harness for damage. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. |
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 | Values | Yes | No |
---|---|---|---|---|
1 | Did you perform the Powertrain OBD System Check? | -- | ||
Are any DTCs set? | -- | Go to applicable DTCs | ||
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 Cooling Insufficient - Air Conditioning (A/C) System in Heating, Ventilation, and Air Conditioning | |
9 | Does the scan tool display A/C request as YES? | -- | Go to Air Conditioning (A/C) Compressor Control Circuit Diagnosis | Go to Cooling Insufficient - Air Conditioning (A/C) System in Heating, Ventilation, and Air Conditioning |
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 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 known good ground. Does the test lamp illuminate? | -- | ||
6 | Probe
the High Speed Fans control circuit (473) at the Cool Fan Relay connector
in the
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 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 (409) 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 (532) for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
12 | Repair the short to voltage in the Cool Fan Relay feed circuit (504). Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
13 | Replace the Cool Fan 1 Relay. Did you complete the repair? | -- | 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. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
15 | Replace the Cool Fan Relay. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
16 |
Important:: Program the replacement PCM. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
Step | Action | Values | Yes | No |
---|---|---|---|---|
1 | Did you perform the Cooling Fan Functional Check? | -- | Go to Cooling Fan Functional Check | |
2 | Did either fan turn on when Cool Fan 1 Relay was commanded on? | -- | ||
3 |
Did the other fan turn off? | -- | ||
4 | With the Low Speed Fans Commanded ON, Disconnect Cool Fan Relay. Did the left fan turn off? | -- | ||
5 |
Does the test lamp illuminate? | -- | ||
6 | Probe both feed circuits (342) at the Cool Fan 1 Relay Connector 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 LH fan feed circuit (532) at the Cool Fan 1 Relay Connector. Do both fans turn on? | -- | ||
8 |
Does the test lamp illuminate? | -- | ||
9 | Connect a second fused jumper wire between the left fan harness connector terminals. Is the right fan on? | -- | ||
10 |
Does the test lamp illuminate? | -- | ||
11 | Using a second jumper wire, jumper the switch feed circuit (504) and the RH fan feed circuit (409) together at Cool Fan Relay connector. Do the fans come on? | -- | ||
12 |
Is the left fan on? | -- | ||
13 |
Did the test lamp illuminate? | -- | ||
14 | Inspect the PCM connections. Repair faulty connections as necessary. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Cooling Fan Functional Check | |
15 | Repair the Low Speed Fans Control circuit (335) for an open or shorted to battery positive voltage. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
16 | Inspect the fan motor ground circuit for a open or the fan motor connections. 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 Cooling Fan Functional Check | |
17 | Replace the faulty fan motor. Refer to Engine Cooling Fan Replacement in Engine Cooling. Did you complete the replacement? | -- | Go to Cooling Fan Functional Check | -- |
18 | Repair the RH fan feed circuit (409) for an open. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
19 | Replace the fan which was not operating. Refer to Engine Cooling Fan Replacement in Engine Cooling. Did you complete the replacement? | -- | Go to Cooling Fan Functional Check | -- |
20 | Replace Cool Fan Relay. Did you complete the replacement? | -- | Go to Cooling Fan Functional Check | -- |
21 | Repair the Cool Fan Relay feed circuit (504) for a short to ground. Refer to Wiring Repairs in Wiring Systems. 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 in Wiring Systems. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
23 | Replace Cool Fan 1 Relay. Did you complete the replacement? | -- | Go to Cooling Fan Functional Check | -- |
24 | Repair the LH fan feed circuit (532) for an open. Refer to Wiring Repairs in Wiring Systems. Did you complete the replacement? | -- | Go to Cooling Fan Functional Check | -- |
25 | Repair the Cool Fan Relay switch feed circuit (504) for an open. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
26 | Replace Cool Fan Relay . Did you complete the replacement? | -- | Go to Cooling Fan Functional Check | -- |
27 |
Important: : Program the replacement PCM. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Cooling Fan Functional Check | -- |
Step | Action | Values | 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 the left fan stop operating? | -- | ||
4 |
Does the test lamp illuminate after several seconds? | -- | ||
5 | Probe the coil feed circuit (1442) at Cool Fan 2 Relay connector using a test lamp that is connected to a known good ground. Does the test lamp illuminate? | -- | ||
6 | Probe the switch feed circuit (1442) at the Cool Fan 2 Relay connector using a test lamp that is connected to a good ground. Does the test lamp illuminate? | -- | ||
7 | Jumper the switch feed circuit (1442) and the RH fan feed circuit (409) together at the Cool Fan 2 Relay connector. 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 Cool Fan Relay connector using a test lamp that is connected to battery positive voltage. Does the test lamp illuminate? | -- | ||
11 | Probe the coil feed circuit (1442) at the Cool Fan Relay connector using a test lamp that is connected to a known good ground. Does the test lamp illuminate? | -- | ||
12 | Repair the High Speed Fans Control circuit (473) for an open between Cool Fan Relay and the splice. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
13 | Repair the open in the Cool Fan 2 Relay coil feed circuit (1442). Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
14 | Repair the open in the Cool Fan 2 Relay switch feed circuit (1442). Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
15 | Replace Cool Fan 2 Relay. Did you complete the replacement? | -- | Go to Cooling Fan Functional Check | -- |
16 | Repair the open in the RH fan feed circuit (409) between Cool Fan 3 Relay and the splice. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
17 | Repair the High Speed Fans Control circuit (473) for an open or for a short to battery positive voltage. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
18 | Repair the open in the High Speed Fans Control circuit (473) between Cool Fan Relay and the splice. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to 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 Cooling Fan Functional Check | -- |
20 | Replace the Cool Fan relay. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
21 | Repair the open in Cool Fan Relay coil feed circuit (1442). Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Cooling Fan Functional Check | -- |
22 | Inspect the PCM connections. Refer to Testing for Intermittent Conditions and Poor Connections , and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Cooling Fan Functional Check | |
23 |
Important: : Program the replacement PCM. Replace the PCM.Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Cooling Fan Functional Check | -- |