P0480

CIRCUIT DESCRIPTION

Engine Control Schematics: Engine Cooling Fan Motors:

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 and Fail 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

NOTE: Refer to Connector Test Adapter Kit J 35616-A Notice in Service Precautions.

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 and Poor Connections in Diagrams.
^ 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 Diagrams.

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

Steps 1 - 9:

Steps 10 - 18:

The numbers below refer to the step numbers on the diagnostic table.
3. 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.
5. Checks for battery positive voltage. The DMM should display battery positive voltage.
6. 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.
7. This checks the PCMs ability to control the low speed fans operation. The DMM should switch between battery positive voltage and 0 V.
8. Checks for battery positive voltage to the low speed fans relay.
9. This check for an open low speed fans control circuit.
11. 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.
17. 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.