Refer to Engine Controls Schematics
Engine Cooling Fan Motors
.
Circuit Description
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 2 relay, DTC P0481 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 2 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
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 2 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 2 relay control circuit and chassis ground. Observe the voltmeter while moving connectors and wiring harnesses related to the engine cooling fan 2 and 3 relays. 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.
-
Ensures battery voltage is present on the High Speed Fans Control circuit with the PCM disconnected.
-
Checks for a short to B+ on the High Speed Fans Control circuit.
-
Checks for shorted relay coils. A shorted relay coil will result in a current reading higher than 1.5 amps.
-
If the current reading from step 4 is not within the specified range, this step determines which relay coil is internally shorted.
-
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 Powertrain On-Board Diagnostic System Check performed? | -- | ||||||||
Is voltage near the specified value? | B+ | |||||||||
Is voltage at the specified value? | 0 V | |||||||||
Does the current reading remain between the specified values? | 0.1-1.5 Amps | |||||||||
Does the current reading remain between the specified values? | 0.1-1.5 Amps | |||||||||
6 | Locate and repair short to voltage in the High Speed Fans control circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||
7 | Check the battery positive feed fuse for the cool fan 2 and cool fan 3 relays. Is the fuse open? | -- | ||||||||
8 |
was a problem found? | -- | Go to Engine Coolant Fan Motor Replacement in Engine Cooling | |||||||
9 |
Is voltage near the specified value? | B+ | ||||||||
10 |
Was a problem found? | -- | ||||||||
11 |
Was a problem found? | -- | ||||||||
12 |
Does the test lamp flash ON and OFF? | -- | Go to Diagnostic Aids | |||||||
13 |
Was a problem found? | -- | ||||||||
14 |
Is the action complete? | -- | -- | |||||||
15 | Replace the cool fan 3 relay. Is the action complete? | -- | -- | |||||||
16 | Replace the cool fan 2 Relay Is the action complete? | -- | -- | |||||||
|
Important: Replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||||||||
18 |
Does scan tool indicate DTC P0481 failed this ign? | -- | System OK |
