rsaz

FYI. Found fan relay mounted on fuse block not in socket. GM # 15016745 (cross w/Airtex 1R1944, $30).

OBD-II trouble code P1482 on Chevrolet Trailblazer.

Research found:
- P1482, Fan Relay 2 Circuit High. P1482, Fan Relay 2 Circuit Low ...
- code P1482 is a fault code for the fan clutch. the engine fan clutch has a electric clutch mounted on front of the fan.

jackyshaikh

If you are good in diagnosis then follow this to solve your problem.

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[/align]DTC P1482 [/align][/align][/align]
Circuit Description
The powertrain control module (PCM) sends a pulse width modulation (PWM) signal of 0-12volts 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 DTCP1482 will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTCP1482 Cooling Fan Speed Output Circuit
Conditions for Running the DTC
System voltage is greater than 8.5volts.
Conditions for Setting the DTC[align=left]



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An improper voltage level has been detected on the cooling fan clutch control circuit.[/align][align=left]



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The above condition is present for at least 6seconds.[/align]
Action Taken When the DTC Sets[align=left]



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The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.[/align][align=left]



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The PCM stores the conditions present when the DTC sets as Freeze Frame/Failure Records data.[/align][align=left]



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The PCM commands the cooling fan clutch to 100percent.[/align]
Conditions for Clearing the MIL/DTC[align=left]



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The PCM turns OFF the MIL after the third consecutive trip the diagnostic has run and passed.[/align][align=left]



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The history DTC will clear after 40consecutive warm-up cycles have occurred without a malfunction.[/align][align=left]



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The DTC can be cleared by using the scan tool Clear DTC Information function.[/align]
Diagnostic Aids[align=left]



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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.[/align][align=left]



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If the condition is not present, refer to Testing for Intermittent Conditions and Poor Connections .[/align][align=left]



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Disconnect the harness connector of the cooling fan clutch from the shroud. Inspect the exposed wires between the harness connector and the tubing.[/align]
Test Description
The numbers below refer to the step numbers on the diagnostic table.
[ol]

The cooling fan noise should increase as the cooling fan clutch engages. It can take up to 2minutes 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.

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.

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.

This step verifies the ignition1 voltage circuit of the cooling fan relay.[/ol]




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 Step2

Go to Diagnostic System Check - Vehicle


1011

[ol]With a scan tool, observe the Powertrain DTC list.
Start the engine.
Operate the vehicle within the Conditions for Running in the DTC. [/ol]
Does the scan tool indicate the DTC Failed this ignition cycle?



Go to Step5

Go to Step3


1617

Important:DTCP1482, for 4.2L (LL8) will set when the cooling fan relay is disconnected.
[ol]Turn OFF the ignition.
Disconnect the coolant fan relay.
Connect a 10-amp fused jumper wire between the cooling fan clutch supply voltage circuit of the cooling fan and the ignition3 voltage circuit of the cooling fan relay.
Start the engine.
Raise engine speed to 2,000RPM for 2minutes. [/ol]
Does the cooling fan engage?



Go to Step4

Go to Step5


2425

Important:Continuously excessive fan noise is due to the powertrain control module (PCM) commanding the cooling fan to 100percent 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.
[ol]Turn OFF the ignition.
Remove the 10-amp fused jumper wire.
Install the cooling fan relay.
Disconnect the cooling fan clutch connector.
Start the engine.
Raise engine speed to 2,000RPM for 2minutes. [/ol]
Does the cooling fan clutch disengage?



Go to Step6

Go to Step16


3233

[ol]Turn OFF the ignition.
Disconnect the cooling fan relay.
Turn ON the ignition, with the engine OFF.
Probe the ignition1 voltage circuit of the cooling fan relay with a test lamp connected a good ground. [/ol]
Does the test lamp illuminate?



Go to Step6

Go to Step10


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 Step18

Go to Step7


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 Step18

Go to Step8


8

[ol]Connect a test lamp to the cooling fan clutch control circuit of the cooling fan relay and battery voltage.
Start the engine.
Command the fan control to 0percent. [/ol]
Does the test lamp flash dim?



Go to Step13

Go to Step9


9

Command the fan control to 100percent.
Does the test lamp flash bright?



Go to Step12

Go to Step13


10

Inspect the Eng Fan fuse.
Is the fuse open?



Go to Step11

Go to Step14


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 Step18

Go to Step14


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 Step18

Go to Step15


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 Step18

Go to Step17


14

Repair the ignition1 voltage circuit of the cooling fan relay. Refer to Wiring Repairs .
Did you complete the repair?



Go to Step18




15

Replace the cooling fan relay.
Did you complete the replacement?



Go to Step18




16

Replace the cooling fan clutch. Refer to Fan Clutch Replacement .
Did you complete the replacement?



Go to Step18




17

Replace the PCM. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?



Go to Step18




18

[ol]Use the scan tool in order to clear the DTCs .
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. [/ol]
Does the DTC reset?



Go to Step2

System OK[/align]. [/align]