DTC P0480 Cooling Fan Relay 1 Control Circuit. Cadillac DeVille 2000

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2000 🢒 DeVille 🢒 DTC 🢒 DTC P0480 Cooling Fan Relay 1 Control Circuit

Refer to Engine Controls Schematics

Engine Cooling Fan Motors

Engine Controls Components
Powertrain Control Module (PCM)
Secondary AIr Injection (AIR) Pump Motors w/NB6 - California Emissions
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Underhood Fuse Block Battery Voltage
Powertrain Control Module Connector End Views
G104 - Relays, Horns and Other Items
Power and Grounding Connector End Views Fuse Blocks and Ignition Switch
.

The PCM uses output driver modules (ODMs) to control many functions of the engine, and the transaxle. The ODMs supply the ground path for the PCM controlled device when the PCM commands the device ON. Each ODM is able to control several outputs. Unlike the quad driver modules (QDMs) used in earlier model years, the ODMs are able to diagnose each output circuit. The PCM monitors the ODMs for circuit conditions that are incorrect for the commanded state of the ODM. If the PCM detects an improper circuit condition in the ODM that controls the engine cooling fan 1 relay, DTC P0480 will set.

Conditions for Running the DTC

•	The engine is running.

•	System voltage is between 8 and 16 volts.

Conditions for Setting the DTC

•	The PCM detects an improper voltage level on the output circuit that controls the engine cooling fan 1 relay.

•	The condition exists for at least 10 seconds.

Action Taken When the DTC Sets

•	The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test runs and fails.

•	The PCM stores the conditions present when the DTC set as Freeze Frame/Failure Records data.

Conditions for Clearing the MIL/DTC

•	The PCM will turn the MIL OFF after the third consecutive trip in which the diagnostic runs and passes.

•	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

Notice: Use the connector test adapter kit J 35616-A for any test that requires probing the following items:

•	The PCM harness connectors

•	The electrical center fuse/relay cavities

•	The component terminals

•	The component harness connector

Using this kit will prevent damage caused by the improper probing of connector terminals.

To determine whether an improper voltage level exists on the output circuit, the PCM compares the voltage level to the commanded state. For example, a failure condition exists if the PCM detects a low voltage level when the device is commanded OFF, or a high voltage level when the device is commanded ON.

Check for the following conditions:

•	Poor connections at the PCM or the engine cooling fan 1 relay--Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

•

Damaged harness--Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the PCM and turn the ignition ON. Connect a voltmeter between the engine cooling fan 1 relay control circuit and chassis ground. Observe the voltmeter while moving connectors and wiring harnesses related to the engine cooling fan 1 relay. A change in voltage will indicate the location of the malfunction. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may assist in diagnosing the condition. The information may help determine how often the condition that set the DTC occurs.

Relay Terminal Identification

Use the Underhood Fuse Block Assembly and/or the Rear Fuse Block Assembly details located in Engine Controls Component Views , to locate the correct cavities to probe during diagnosis. Four blade relays can be inserted two ways. The number designations (i.e., 30, 85, 86, 87, and 87a) displayed on the relays correspond directly to the cavity and NOT the numbering on the relay.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

Determines whether the continuous low speed fan operation is a short to ground or a malfunctioning PCM. With the PCM disconnect, the DMM should display 0 V.

Checks for battery positive voltage. The DMM should display battery positive voltage.

Check for a short to voltage or a shorted relay. Although battery positive voltage is present, a high current draw will cause thermal shut down of the low speed fans driver.

This checks the PCMs ability to control the low speed fans operation. The DMM should switch between battery positive voltage and 0 V.

Checks for battery positive voltage to the low speed fans relay.

This check for an open low speed fans control circuit.

Determines if the high current draw is the fault of the low speed fans relay or a short between battery positive voltage and the low speed fans control circuit. If the PCM displays 0 V, the relay is suspect. If not, the low speed fans control circuit is shorted to battery positive voltage.

This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read only memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

Step	Action	Values	Yes	No
1	Was the On-Board Diagnostic (OBD) System Check performed?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Do the engine cooling fans run continuously?	--	Go to Step 3	Go to Step 5
3	Turn the ignition to the OFF position. Remove the low speed fan relay. Disconnect the PCM connector. Using the appropriate jumpers, connect DMM J 39200 between the battery positive feed and the low speed fan control circuit cavities in the relay connector. Does the DMM indicate a voltage near the specified value?	B+	Go to Step 4	Go to Step 17
4	Locate and repair the short to ground in the Low Speed Fans control circuit (CKT 335). Refer to Wiring Repairs in Wiring Systems. Is the action complete?	--	Go to Step 18	--
5	Disconnect the PCM connector. Using the DMM, measure the voltage between the Low Speed Fans control circuit and ground. Does the DMM display a voltage near the specified value?	B+	Go to Step 6	Go to Step 8
6	Leave the PCM disconnected. Set the DMM to the 10 amp scale. Measure the current between the Low Speed Fans control circuit and ground. Monitor the reading for a minimum of 2 minutes. Does the DMM display a current reading within the specified values?	0.1-1.5 Amps	Go to Step 7	Go to Step 11
7	Remove the low speed fans relay. Reconnect the PCM connector. Using the appropriate jumpers, connect the DMM between the battery feed circuit and the low speed fans control circuit cavities in the relay connector. Using a scan tool, command fan 1 ON and OFF. Does the DMM display the first value when fan 1 is commanded ON, and the second value when fan 1 is commanded OFF?	B+ 0V	Go to Diagnostic Aids	Go to Step 12
8	Leave the PCM disconnected. Remove the low speed fans relay. Using the DMM, check the battery positive feed circuit in the relay connector. Does the DMM display a voltage near the specified value?	B+	Go to Step 9	Go to Step 13
9	Leave the PCM disconnected Leave the relay disconnected. Connect a fused jumper between the battery positive feed circuit and the low speed fans control circuit cavities in the relay connector. Using the DMM, measure the voltage between the low speed fans control circuit in the PCM connector and chassis ground. Does the DMM display a voltage near the specified value?	B+	Go to Step 10	Go to Step 14
10	Check for poor terminal connections in the relay connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. If a problem is found, repair as necessary. Refer to Repairing Connector Terminals in Wiring Systems. Was a problem found?	--	Go to Step 18	Go to Step 15
11	Leave the PCM disconnected. Remove the low speed fans relay. Using the DMM, measure the voltage between the Low Speed Fans control circuit and ground. Does the DMM display a voltage near the specified value?	0V	Go to Step 15	Go to Step 16
12	Check for poor connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. If a problem is found, repair as necessary. Refer to Repairing Connector Terminals in Wiring Systems. Was a problem found?	--	Go to Step 18	Go to Step 17
13	Check for an open or short to ground in the battery positive feed to the low speed fans relay. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Important: Be sure to replace the fuse. Was a problem found?	--	Go to Step 18	Go to Engine Coolant Fan Motor Replacement in Engine Cooling
14	Locate and repair the open in the Low Speed Fans control circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete?	--	Go to Step 18	--
15	Replace the low speed fans relay. Is the action complete?	--	Go to Step 18	--
16	Locate and repair the short to voltage in the Low Speed Fans control circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete?	--	Go to Step 18	--
17	Important: Replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete?	--	Go to Step 18	--
18	Review and record scan tool Fail Records data. Clear DTCs. Operate vehicle within Fail Records conditions as noted. Using a scan tool, monitor SPECIFIC DTC info for DTC P0480 until the DTC P0480 test runs. Does the scan tool indicate DTC P0480 failed this ign?	--	Go to Step 2	System OK