Why is your 2005 Impala engine temperature rising while idle significantly but returns to normal while driving?

Answer 1

Step Action Yes No Schematic Reference: Engine Cooling Schematics Connector End View Reference: Cooling System Connector End Views DEFINITION: One or both engine cooling fan motors do not operate properly in high or low speed modes. 1 Did you perform the Diagnostic System Check - Vehicle? Go to Step 2 Go to Diagnostic System Check - Vehicle in Vehicle DTC Information 2

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, command the Fans Low Speed ON and OFF.

Do the low speed engine cooling fans turn ON and OFF with each command? Go to Step 3 Go to Step 4 3 Important:: A 3 second delay occurs before the powertrain control module (PCM) changes the cooling fan speed.
With a scan tool, command the Fans High Speed ON and OFF. Do the high speed engine cooling fans turn ON and OFF with each command? Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 12 4

Important: Do NOT remove the 20-amp fused jumper wire connected during this step. Use a second 20-amp fused jumper wire while performing the following steps.

1. Remove the FAN CONT #1 relay.
2. Connect a 20-amp fused jumper between the battery positive switch side voltage circuit and the cooling fan motor supply voltage circuit of the FAN CONT #1 relay.

Do both cooling fans operate in low speed? Go to Step 22 Go to Step 5 5

1. Disconnect the FAN CONT #2 relay
2. Connect the second 20-amp fused jumper between the cooling fan low reference circuit and the cooling fan motor supply voltage circuit of the FAN CONT #2 relay.

Do both cooling fans operate in low speed? Go to Step 23 Go to Step 6 6 Connect the second 20-amp fused jumper between the battery positive voltage circuit and the cooling fan motor supply voltage circuit of the FAN CONT #2 relay. Does the right cooling fan operate in high speed? Go to Step 9 Go to Step 7 7

1. Install the FAN CONT #2 relay.
2. Disconnect the right cooling fan electrical connector.
3. Connect the second 20-amp fused jumper wire from the cooling fan motor supply voltage circuit to the ground circuit of the right cooling fan electrical connector.

Does the left cooling fan operate in high speed? Go to Step 25 Go to Step 8 8 Connect the second 20-amp fused jumper wire from the cooling fan motor supply voltage circuit of the right cooling fan electrical connector to a good ground. Does the left cooling fan operate in high speed? Go to Step 29 Go to Step 30 9

1. Install the FAN CONT #2 relay.
2. Disconnect the left cooling fan electrical connector.
3. Connect the second 20-amp fused jumper wire from the cooling fan motor supply voltage circuit to the cooling fan low reference circuit of the left cooling fan electrical connector.

Does the right cooling fan operate in high speed? Go to Step 26 Go to Step 10 10 Connect the second 20-amp fused jumper wire from the coil side battery positive voltage circuit to the cooling fan low reference circuit of the of the left cooling fan electrical connector. Does the right cooling fan operate in high speed? Go to Step 11 Go to Step 31 11 Probe the battery positive voltage circuit on the switch side of the FAN CONT #1 relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? Go to Step 27 Go to Step 32 12 Is the right cooling fan operating properly in high speed? Go to Step 19 Go to Step 13 13

1. Turn off the ignition.
2. Disconnect the FAN CONT #3 relay.
3. Turn ON the ignition, with the engine OFF.
4. Connect a test lamp between the high speed cooling fan relay control circuit and the battery positive voltage circuit on the coil side of the FAN CONT #3 relay.
5. With a scan tool command the High Speed Fans ON and OFF.

Does the test lamp turn ON and OFF with each command? Go to Step 15 Go to Step 14 14 Probe the battery positive voltage circuit on the coil side of the FAN CONT #3 relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? Go to Step 34 Go to Step 33 15 Install a 20-amp fused jumper between the battery positive voltage circuit on the switch side of the FAN CONT #3 relay and the cooling fan motor supply voltage circuit. Does the right cooling fan operate in high speed? Go to Step 24 Go to Step 16 16 Probe the battery positive voltage circuit on the switch side of the FAN CONT #3 relay with a test lamp connected to a good ground. Does the test lamp illuminate? Go to Step 17 Go to Step 33 17

1. With the 20-amp fused jumper still installed.
2. Disconnect the left cooling fan electrical connector.
3. Connect a test lamp from the cooling fan motor supply voltage circuit to the ground circuit of the right cooling fan electrical connector.

Does the test lamp illuminate? Go to Step 25 Go to Step 18 18 Probe the cooling fan motor supply voltage circuit of the right cooling fan electrical connector with a test lamp that is connected to a good ground. Does the test lamp illuminate? Go to Step 29 Go to Step 30 19

1. Turn OFF the ignition.
2. Disconnect the FAN CONT #2 relay
3. Turn ON the ignition, with the engine OFF.
4. Connect a 20-amp fused jumper between the cooling fan low reference circuit and the ground circuit of the FAN CONT #2 relay.
5. With a scan tool command the Fans High Speed ON and OFF.

Does the left cooling fan operate in high speed? Go to Step 20 Go to Step 28 20

1. Connect a test lamp between the high speed cooling fan relay control circuit of the FAN CONT #2 relay and the battery positive voltage circuit of the FAN CONT #2 relay.
2. With a scan tool command the Fans High Speed ON and OFF.

Does the test lamp turn ON and OFF with each command? Go to Step 23 Go to Step 21 21 Probe the battery positive voltage circuit of the FAN CONT #2 relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? Go to Step 34 Go to Step 33 22 Inspect for poor connections at the FAN CONT #1 relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? Go to Step 40 Go to Step 35 23 Inspect for poor connections at the FAN CONT #2 relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? Go to Step 40 Go to Step 36 24 Inspect for poor connections at the FAN CONT #3 relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? Go to Step 40 Go to Step 37 25 Inspect for poor connections at the harness connector of the right cooling fan. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? Go to Step 40 Go to Step 38 26 Inspect for poor connections at the harness connector of the left cooling fan. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? Go to Step 40 Go to Step 39 27 Repair the left cooling fan motor supply voltage circuit for an open. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? Go to Step 40 -- 28 Repair the left cooling fan ground circuit for an open. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? Go to Step 40 -- 29 Repair the right cooling fan ground circuit for an open. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? Go to Step 40 -- 30 Repair the right cooling fan motor supply voltage circuit for an open. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? Go to Step 40 -- 31 Repair the left cooling fan low reference circuit for a short to ground or an open. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? Go to Step 40 -- 32 Repair the FAN CONT #1 relay battery positive voltage circuit for an open. Is the repair complete? Go to Step 40 -- 33 Repair the battery positive voltage circuit for the FAN CONT #2 and #3 relay for an open. Is the repair complete? Go to Step 40 -- 34 Repair the high speed cooling fan relay control circuit for an open. Is the repair complete? Go to Step 40 -- 35 Replace the FAN CONT #1 relay. Is the repair complete? Go to Step 40 -- 36 Replace the FAN CONT #2 relay. Is the repair complete? Go to Step 40 -- 37 Replace the FAN CONT #3 relay. Is the repair complete? Go to Step 40 -- 38 Replace the right cooling fan. Refer to Cooling Fan Motor Replacement - Electric . Is the repair complete? Go to Step 40 -- 39 Replace the left cooling fan. Refer to Cooling Fan Motor Replacement - Electric . Is the repair complete? Go to Step 40 -- 40 Operate the system in order to verify the repair. Did you correct the condition? System OK Go to Step 3
I don't know if this is what you are looking for but I hope this is helpful.
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