NO.21 CONSTANT VOLTAGE [WL-3]
id0103b5914100
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21
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Constant voltage
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DESCRIPTION
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• Incorrect constant voltage
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POSSIBLE CAUSE
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• Constant voltage circuit malfunction
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Diagnostic procedure
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STEP |
INSPECTION |
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ACTION |
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1
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• Disconnect the APP sensor connector.
• Turn the engine switch to the ON position (Engine off).
• Measure the voltage between the following APP sensor connector terminals:
• Is the constant voltage above 6.0 V?
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Yes
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Repair the constant voltage circuit short to power in harness.
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No
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Go to the next step.
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2
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• Is the voltage across battery terminals above 10.5 V?
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Yes
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Go to the next step.
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No
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Inspect the charging system.
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3
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• Turn the engine switch to the off position.
• Disconnect the sensor where the constant voltage inspection failed.
• Measure the voltage between the battery positive post and the ground circuit at the appropriate sensor vehicle wiring harness connector.
• Is the voltage above 10.5 V and within 1.0 V of the battery voltage?
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Yes
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Go to the next step.
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No
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Go to Step 9.
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4
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• Turn the engine switch to the ON position (Engine off).
• Connect the M-MDS to the DTC.
• Attempt to access the ECT PID.
• Can the ECT PID be accessed?
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Yes
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Inspect for an open constant voltage supply circuit between PCM connector terminal 1A and the suspect sensor connector.
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No
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Go to the next step.
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5
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• Turn the engine switch to the off position.
• Disconnect the APP sensor connector.
• Disconnect the EGR solenoid valve (vacuum) connector.
• Turn the engine switch to the ON position (Engine off).
• Measure the voltage between the power supply circuit at the EGR solenoid valve (vacuum) connector and the battery negative post.
• Is the voltage above 10.5 V?
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Yes
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Reconnect the EGR solenoid valve (vacuum).
Go to the next step.
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No
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Battery power is not present.
Inspect the following:
• MAIN fuse and/or PCM fuse
• Main relay
• Open circuit between MAIN fuel and main relay
• Open circuit between main relay and EGR solenoid valve (vacuum)
• Open circuit between main relay and PCM terminal 3B
• Open circuit between main relay and PCM terminal 4C/4D
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6
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• Turn the engine switch to the off position.
• Leave the APP sensor disconnected.
• Disconnect the MAF sensor/IAT sensor No.2 connector.
• Turn the engine switch to the ON position (Engine off).
• Measure the voltage between following the APP sensor connector terminals:
• Is the voltage 4.0—6.0 V?
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Yes
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Replace the MAF sensor/IAT sensor No.2.
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No
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Go to the next step.
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7
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• Turn the engine switch to the off position.
• Leave the APP sensor and MAF sensor/IAT sensor No.2 connectors disconnected.
• Disconnect the boost sensor connector.
• Turn the engine switch to the ON position (Engine off).
• Measure the voltage between the constant voltage and ground terminals at the APP sensor connector.
• Is the voltage 4.0—6.0 V?
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Yes
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Replace the boost sensor.
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No
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Go to the next step.
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8
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• Turn the engine switch to the off position.
• Leave the APP sensor disconnected.
• Disconnect the MAF sensor/IAT sensor No.2 and boost sensor connectors.
• Turn the engine switch to the ON position (Engine off).
• Connect the M-MDS to the DLC.
• Access the B+ PID.
• Is the B+ PID above 10.5 V?
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Yes
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Inspect the constant voltage circuit for a short to ground.
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No
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Inspect for an open battery power supply circuit between the main relay and PCM terminal 4C/4D.
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9
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• Turn the engine switch to the ON position (Engine off).
• Connect the M-MDS to the DLC.
• Attempt to access the ECT PID.
• Can the ECT PID be accessed?
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Yes
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Go to the next step.
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No
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Go to Step 11.
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10
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• Are DTCs present for two or more of the following sensors connected to the PCM 1B terminal?
• Boost sensor.
• MAF sensor/IAT sensor No.2.
• APP sensor.
• ECT sensor.
• IAT sensor No.1.
• Fuel temperature sensor.
• EGR position sensor.
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Yes
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Go to the next step.
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No
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Inspect for a poor ground circuit of the sensor where the constant voltage inspection failed.
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11
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• Turn the engine switch to the off position.
• Disconnect the M-MDS from the DLC.
• Disconnect the sensor where the constant voltage inspection failed.
• Inspect for continuity between the ground circuit at the appropriate sensor connector and body ground.
• Is there continuity?
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Yes
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Inspect for the constant voltage at the suspect sensor connector again.
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No
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Inspect for open ground circuit between the following terminals:
• PCM connector 4A/4B terminals and the ground.
• PCM connector 4A/4B and 1B terminals.
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12
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Verify test results.
• If normal, return to the diagnostic index to service any additional symptoms.
• If a malfunction remains, inspect the related Service Information and/or on-line repair information and perform the repair or diagnosis.
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