Please Help! Code P0480
Thread Starter
Intermediate
Joined: Oct 2006
Posts: 46
Likes: 0
Please Help! Code P0480
I have the P0480 code ( Cooling Fan Relay 1 Control Circuit) and I cannot figure out what is causing it. Don't know very much about electrical stuff so I need some major help.
I have replaced relay #45 - looked fine when I pulled it.
Checked relays # 43 & 44 - they look fine.
I have checked fuses 14, 46, and 49 - they all look ok.
Here is the tech info - doesn't make much sense to me.
http://www.gearchatter.com/viewtopic8557.php
What should I do next? Thanks for your help!
I have replaced relay #45 - looked fine when I pulled it.
Checked relays # 43 & 44 - they look fine.
I have checked fuses 14, 46, and 49 - they all look ok.
Here is the tech info - doesn't make much sense to me.
http://www.gearchatter.com/viewtopic8557.php
What should I do next? Thanks for your help!
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,396
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Heres the entire service manual troubleshooting procedure. If you have ant questions, please let me know:
DTC P0480
Circuit Description
Battery positive voltage is supplied to the coolfan 1 relay from the coolfan 1 fuse. The powertrain control module (PCM) controls the coolfan 1 relay by grounding the low speed coolfan relay control circuit through an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component on, the voltage potential of the control circuit should be low, near 0 volts. When the PCM is commanding the control circuit to a component off, the voltage potential of the circuit should be high, near battery voltage. If the fault detection circuit senses a voltage other than what is expected, the DTC will set.
The PCM will monitor the control circuit for the following:
A short to ground
A short to voltage
An open circuit
An open relay coil
An internally shorted or excessively low resistance relay coil.
When the PCM detects any of the above conditions, the DTC will set and the affected driver will be disabled.
Conditions for Running the DTC
The ignition voltage is between 6 and 18 volts.
The engine speed is more than 400 RPM.
Conditions for Setting the DTC
An improper voltage level has been detected on the low speed coolfan relay control circuit.
The above conditions are present for at least 5 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 will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.
Conditions for Clearing the MIL/DTC
The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been 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.
Diagnostic Aids
Check for the following conditions:
A faulty connection at the PCM, inspect the harness connectors for the following conditions.
Backed out terminals
Improper mating
Broken locks
Improperly formed or damaged terminals
Faulty terminal to wire connections
Inspect the wiring harness for damage.
If the harness appears to be OK, disconnect the PCM, turn the ignition ON and observe a digital multimeter (DMM) connected between the low speed coolfan relay control circuit of the coolfan 1 relay and ground at the PCM harness connector. While moving connectors and the wiring harness related to the coolfan 1 relay, a change in voltage will indicate the location of the fault.
Review the Freeze/Failure Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Listen for an audible click when the coolfan 1 relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
Tests for voltage at the coil side of the coolfan 1 relay. The coolfan 1 fuse supplies battery positive voltage to the coil side of the coolfan 1 relay.
Verifies that the PCM is providing ground to the coolfan 1 relay.
Tests if ground is constantly being applied to the coolfan 1 relay.
Step
Action
Yes
No
Schematic Reference: Engine Cooling Schematics
Connector End View Reference: Cooling System Connector End Views
1
Did you perform the Engine Cooling Diagnostic System Check?
Go to Step 2
Go to Diagnostic System Check - Engine Cooling
2
Install a scan tool.
Turn ON the ignition, with the engine OFF.
With a scan tool, command the Fan Relay 1 ON and OFF.
Does the coolfan 1 relay turn ON and OFF with each command?
Go to Diagnostic Aids
Go to Step 3
3
Turn OFF the ignition.
Disconnect the coolfan 1 relay
Turn ON the ignition, with the engine OFF.
Probe the battery voltage circuit of the coolfan 1 relay with a test lamp that is connected to a good ground.
Does the test lamp illuminate?
Go to Step 4
Go to Step 10
4
Connect a test lamp between the control circuit of the coolfan 1 relay and the battery positive voltage circuit of the coolfan 1 relay.
With a scan tool, command the Fan Relay 1 ON and OFF .
Does the test lamp turn ON and OFF with each command?
Go to Step 8
Go to Step 5
5
Does the test lamp remain illuminated with each command?
Go to Step 7
Go to Step 6
6
Test the control circuit of the coolfan 1 relay for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 14
Go to Step 9
7
Test the control circuit of the coolfan 1 relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 14
Go to Step 9
8
Inspect for poor connections at the coolfan 1 relay. Refer to the following procedures in Wiring Systems.
Circuit Testing
Wiring Repairs
Did you find and correct the condition?
Go to Step 14
Go to Step 12
9
Inspect for poor connections at the harness connector of the PCM. Refer to the following procedures in Wiring Systems.
Circuit Testing
Wiring Repairs
Did you find and correct the condition?
Go to Step 14
Go to Step 13
10
Test the battery positive voltage circuit for an open or a short to ground. Refer to the following procedures in Wiring Systems:
Circuit Testing
Wiring Repairs
Did you find and correct the condition?
Go to Step 14
Go to Step 11
11
Repair the coolfan motor supply voltage circuit for a short to ground. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 14
--
12
Replace the coolfan 1 relay.
Did you complete the replacement?
Go to Step 14
--
13
Important
Perform the set up procedure for the PCM.
Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement in Engine Controls.
Did you complete the replacement?
Go to Step 14
--
14
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.
Does the DTC reset?
Go to Step 2
System OK
BC
DTC P0480
Circuit Description
Battery positive voltage is supplied to the coolfan 1 relay from the coolfan 1 fuse. The powertrain control module (PCM) controls the coolfan 1 relay by grounding the low speed coolfan relay control circuit through an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component on, the voltage potential of the control circuit should be low, near 0 volts. When the PCM is commanding the control circuit to a component off, the voltage potential of the circuit should be high, near battery voltage. If the fault detection circuit senses a voltage other than what is expected, the DTC will set.
The PCM will monitor the control circuit for the following:
A short to ground
A short to voltage
An open circuit
An open relay coil
An internally shorted or excessively low resistance relay coil.
When the PCM detects any of the above conditions, the DTC will set and the affected driver will be disabled.
Conditions for Running the DTC
The ignition voltage is between 6 and 18 volts.
The engine speed is more than 400 RPM.
Conditions for Setting the DTC
An improper voltage level has been detected on the low speed coolfan relay control circuit.
The above conditions are present for at least 5 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 will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.
Conditions for Clearing the MIL/DTC
The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been 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.
Diagnostic Aids
Check for the following conditions:
A faulty connection at the PCM, inspect the harness connectors for the following conditions.
Backed out terminals
Improper mating
Broken locks
Improperly formed or damaged terminals
Faulty terminal to wire connections
Inspect the wiring harness for damage.
If the harness appears to be OK, disconnect the PCM, turn the ignition ON and observe a digital multimeter (DMM) connected between the low speed coolfan relay control circuit of the coolfan 1 relay and ground at the PCM harness connector. While moving connectors and the wiring harness related to the coolfan 1 relay, a change in voltage will indicate the location of the fault.
Review the Freeze/Failure Records vehicle mileage since the diagnostic test last failed. This may help determine how often the condition that caused the DTC to be set occurs.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Listen for an audible click when the coolfan 1 relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
Tests for voltage at the coil side of the coolfan 1 relay. The coolfan 1 fuse supplies battery positive voltage to the coil side of the coolfan 1 relay.
Verifies that the PCM is providing ground to the coolfan 1 relay.
Tests if ground is constantly being applied to the coolfan 1 relay.
Step
Action
Yes
No
Schematic Reference: Engine Cooling Schematics
Connector End View Reference: Cooling System Connector End Views
1
Did you perform the Engine Cooling Diagnostic System Check?
Go to Step 2
Go to Diagnostic System Check - Engine Cooling
2
Install a scan tool.
Turn ON the ignition, with the engine OFF.
With a scan tool, command the Fan Relay 1 ON and OFF.
Does the coolfan 1 relay turn ON and OFF with each command?
Go to Diagnostic Aids
Go to Step 3
3
Turn OFF the ignition.
Disconnect the coolfan 1 relay
Turn ON the ignition, with the engine OFF.
Probe the battery voltage circuit of the coolfan 1 relay with a test lamp that is connected to a good ground.
Does the test lamp illuminate?
Go to Step 4
Go to Step 10
4
Connect a test lamp between the control circuit of the coolfan 1 relay and the battery positive voltage circuit of the coolfan 1 relay.
With a scan tool, command the Fan Relay 1 ON and OFF .
Does the test lamp turn ON and OFF with each command?
Go to Step 8
Go to Step 5
5
Does the test lamp remain illuminated with each command?
Go to Step 7
Go to Step 6
6
Test the control circuit of the coolfan 1 relay for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 14
Go to Step 9
7
Test the control circuit of the coolfan 1 relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 14
Go to Step 9
8
Inspect for poor connections at the coolfan 1 relay. Refer to the following procedures in Wiring Systems.
Circuit Testing
Wiring Repairs
Did you find and correct the condition?
Go to Step 14
Go to Step 12
9
Inspect for poor connections at the harness connector of the PCM. Refer to the following procedures in Wiring Systems.
Circuit Testing
Wiring Repairs
Did you find and correct the condition?
Go to Step 14
Go to Step 13
10
Test the battery positive voltage circuit for an open or a short to ground. Refer to the following procedures in Wiring Systems:
Circuit Testing
Wiring Repairs
Did you find and correct the condition?
Go to Step 14
Go to Step 11
11
Repair the coolfan motor supply voltage circuit for a short to ground. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 14
--
12
Replace the coolfan 1 relay.
Did you complete the replacement?
Go to Step 14
--
13
Important
Perform the set up procedure for the PCM.
Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement in Engine Controls.
Did you complete the replacement?
Go to Step 14
--
14
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.
Does the DTC reset?
Go to Step 2
System OK
BC
Thread Starter
Intermediate
Joined: Oct 2006
Posts: 46
Likes: 0
Yeah, I have this (that's what I linked too).
How do I do this?
"turn the ignition ON and observe a digital multimeter (DMM) connected between the low speed coolfan relay control circuit of the coolfan 1 relay and ground at the PCM harness connector. While moving connectors and the wiring harness related to the coolfan 1 relay, a change in voltage will indicate the location of the fault"
How do I do this?
"turn the ignition ON and observe a digital multimeter (DMM) connected between the low speed coolfan relay control circuit of the coolfan 1 relay and ground at the PCM harness connector. While moving connectors and the wiring harness related to the coolfan 1 relay, a change in voltage will indicate the location of the fault"
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,396
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Remove the relay and insert a small piece of stranded wire in the socket hole for that circuit and then reinsert the relay. Attach the meter lead to that wire and the other meter lead to ground.
BC
BC
