Circuit Description
The powertrain control module (PCM) sends a pulse width modulation (PWM) signal of 0-12 volts via the cooling fan clutch control circuit to the cooling fan relay. The PCM uses this PWM to control the position of the oil control valve located inside the cooling fan clutch. If during operation, the PCM detects an improper circuit condition on the cooling fan clutch control circuit DTC P1482 will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1482 Cooling Fan Speed Output Circuit
Conditions for Running the DTC
System voltage is greater than 8.5 volts.
Conditions for Setting the DTC
| • | An improper voltage level has been detected on the cooling fan clutch control circuit. |
| • | The above condition is present for at least 6 seconds. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM stores the conditions present when the DTC sets as Freeze Frame/Failure Records data. |
| • | The PCM commands the cooling fan clutch to 100 percent. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL after the third consecutive trip the diagnostic has run and passed. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool Clear DTC Information function. |
Diagnostic Aids
| • | An inline connector could cause an intermittent DTC. Ensure to test for poor connections and pin retention at all inline connectors. Refer to system schematics for connector and locations. |
| • | If the condition is not present, refer to Testing for Intermittent Conditions and Poor Connections . |
| • | Disconnect the harness connector of the cooling fan clutch from the shroud. Inspect the exposed wires between the harness connector and the tubing. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The cooling fan noise should increase as the cooling fan clutch engages. It can take up to 2 minutes for full cooling fan clutch engagement. If cooling fan clutch is previously fully engaged, then there will not be a noticeable change in cooling fan noise. Compare noise to a known good vehicle. If fan noise is louder than the known good vehicle, answer Yes.
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In the previous step the cooling fan clutch was fully engaged. This step tests to ensure that the cooling fan clutch will disengage. A noticeable noise difference should be heard between a fully engaged cooling fan clutch and a disengaged cooling fan clutch. The cooling fan clutch is completely disengaged when the excessive fan noise is not heard.
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This step tests for the ability of the PCM to control cooling fan clutch speed. If answer to question is Yes, refer to all Diagnostic Aids.
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This step verifies the ignition 1 voltage circuit of the cooling fan relay.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Cooling Schematics Connector End View Reference: Cooling System Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
Does the scan tool indicate the DTC Failed this ignition cycle? | -- | Go to Step 5 | Go to Step 3 | |
|
Important: DTC P1482, for 4.2L (LL8) will set when the cooling fan relay is disconnected.
Does the cooling fan engage? | -- | Go to Step 4 | Go to Step 5 | |
|
Important: Continuously excessive fan noise is due to the powertrain control module (PCM) commanding the cooling fan to 100 percent engaged or a mechanical failure. If the fan noise decreases during this step, then this DTC is due to an electrical malfunction. Replacing the cooling fan will not correct the condition.
Does the cooling fan clutch disengage? | -- | Go to Step 6 | Go to Step 16 | |
Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 10 | |
6 | Test the cooling fan clutch control circuit of the cooling fan relay for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 7 |
7 | Test the cooling fan clutch control circuit of the cooling fan relay for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 8 |
8 |
Does the test lamp flash dim? | -- | Go to Step 13 | Go to Step 9 |
9 | Command the fan control to 100 percent. Does the test lamp flash bright? | -- | Go to Step 12 | Go to Step 13 |
10 | Inspect the Eng Fan fuse. Is the fuse open? | -- | Go to Step 11 | Go to Step 14 |
11 | Test the cooling fan clutch control circuit of the cooling fan relay for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 14 |
12 | Inspect for poor connections at the cooling fan relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 15 |
13 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 17 |
14 | Repair the ignition 1 voltage circuit of the cooling fan relay. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 18 | -- |
15 | Replace the cooling fan relay. Did you complete the replacement? | -- | Go to Step 18 | -- |
16 | Replace the cooling fan clutch. Refer to Fan Clutch Replacement . Did you complete the replacement? | -- | Go to Step 18 | -- |
17 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 18 | -- |
18 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
