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Home >> Freightliner Truck >> 2008 >> Sprinter 2500 V6-3.0L DSL Turbo >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> Manufacturer Code Charts >> Alphanumeric Codes >> 5xxx Codes >> 51A5

51A5







51A5-IMPLAUSIBLE ACCELERATOR PEDAL MESSAGE RECEIVED

For a complete wiring diagram Consult Diagrams/Electrical.

- When Monitored:
With the ignition on and no APPS No.1 and APPS No.2 DTC present.

- Set Condition:
APPS values No.1 and No.2 are not coherent. Idle is additionally forced when the brake pedal is pressed or failed. Acceleration rate and Engine output are limited. One trip fault and the code will set within 5 seconds. ETC light is flashing.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview.

Diagnostic Test

1. ACTIVE DTC
Start the engine and allow it to reach normal operating temperature.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

NOTE: Diagnose and repair any system voltage or sensor supply voltage DTCs before continuing with this test.

NOTE: If you are viewing data recorder information or Freeze Frame data the APP Sensor No. 2 is pulled low by the PCM as part of its system testing. This test happens every 320 milliseconds and may not show up on the scan tool but may show up on a data recorder or lab scope. It is acceptable to see the voltage close to zero with a normal sensor when using a data recorder/lab scope.

With the scan tool, select View DTCs.
Is the DTC Active at this time?

Yes

- Go To 2

No

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure.

2. EXCESSIVE RESISTANCE IN THE APPS NO.1 SIGNAL CIRCUIT
Turn the ignition off.
Disconnect the C3 harness connector.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 along with the #8815-1 to perform the diagnosis.

Using a voltmeter perform a voltage drop test. Backprobe the APPS No.1 Signal circuit at the APPS harness connector and probe the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so a positive polarity is displayed on the voltmeter.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

Start the engine and allow it to reach normal operating temperature.
Monitor the voltmeter.
Is the voltage below 0.5 of a volt?

Yes

- Go To 3

No

- Repair the excessive resistance in the APP Sensor No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Verification Tests.

3. EXCESSIVE RESISTANCE IN THE SENSOR NO.1 RETURN CIRCUIT
Turn the ignition off.
Move the voltmeter leads to backprobe the APPS No.1 Return circuit at the APPS harness connector and probe the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so a positive polarity is displayed on the voltmeter.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

Start the engine and allow it to reach normal operating temperature.
Monitor the voltmeter.
Is the voltage below 0.5 of a volt?

Yes

- Go To 4

No

- Repair the excessive resistance in the Sensor No.1 Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Verification Tests.

4. EXCESSIVE RESISTANCE IN THE APPS NO.2 SIGNAL CIRCUIT
Turn the ignition off.
Move the voltmeter leads to backprobe the APPS No.2 Signal circuit at the APPS harness connector and probe the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so a positive polarity is displayed on the voltmeter.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

Start the engine and allow it to reach normal operating temperature.
Monitor the voltmeter.
Is the voltage below 0.5 of a volt?

Yes

- Go To 5

No

- Repair the excessive resistance in the APP Sensor No.2 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Verification Tests.

5. EXCESSIVE RESISTANCE IN THE SENSOR NO.2 RETURN CIRCUIT
Turn the ignition off.
Move the voltmeter leads to backprobe the APPS No.2 Return circuit at the APPS harness connector and probe the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so a positive polarity is displayed on the voltmeter.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

Start the engine and allow it to reach normal operating temperature.
Monitor the voltmeter.
Is the voltage below 0.5 of a volt?

Yes

- Go To 6

No

- Repair the excessive resistance in the Sensor No.2 Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Verification Tests.

6. EXCESSIVE RESISTANCE IN THE 5-VOLT SUPPLY CIRCUIT
Turn the Ignition off.
Remove special tool #8815 from the C3 PCM harness connector and Re-Connect the C3 PCM harness connector to the PCM.
Disconnect the C2 PCM harness connector to install special tool #8815 and #8815-1.
Using a voltmeter perform a voltage drop test. Backprobe the 5-volt Supply circuit at the APPS harness connector and probe the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so a positive polarity is displayed on the voltmeter.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

Start the engine and allow it to reach normal operating temperature.
Monitor the voltmeter.
Is the voltage below 0.5 of a volt?

Yes

- Go To 7

No

- Repair the excessive resistance in the 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Verification Tests.

7. EXCESSIVE RESISTANCE IN THE 5-VOLT SUPPLY CIRCUIT
Turn the Ignition off.
Remove special tool #8815 from the C2 PCM harness connector and Re-Connect the C2 PCM harness connector to the PCM.
Disconnect the C1 PCM harness connector to install special tool #8815 and #8815-1.
Using a voltmeter perform a voltage drop test. Backprobe the 5-volt Supply circuit at the APPS harness connector and probe the appropriate terminal of the special tool #8815. Make sure the voltmeter leads are connected so a positive polarity is displayed on the voltmeter.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

Start the engine and allow it to reach normal operating temperature.
Monitor the voltmeter.
Is the voltage below 0.5 of a volt?

Yes

- Go To 8

No

- Repair the excessive resistance in the 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Verification Tests.

8. CHECKING APPS NO.1 AND NO.2 WITH A LAB SCOPE
Turn the Ignition off.
Remove special tool #8815 and Re-Connect the C1 PCM harness connector.
Ignition on, engine not running.
Set up a lab scope in a way that you can view two graphs simultaneously.
Backprobe APP Sensor No.1 Signal circuit using Channel 1 at the APP Sensor harness connector.
Backprobe APP Sensor No.2 Signal circuit using Channel 2 at the APP Sensor harness connector.

NOTE: The APP Sensor No. 2 is pulled low by the PCM as part of its system testing. This test happens every 320 milliseconds and may not show up on the scan tool but may show up on a data recorder. It is acceptable to see the voltage close to zero with a normal sensor when using a data recorder/lab scope.

Slowly press and release the Accelerator Pedal while monitoring the lab scope screen.
Does the scope pattern show any missing or erratic signals?

Yes

- Replace the APP Sensor Assembly. After installation is complete, use a scan tool and select the ETC RELEARN function to relearn the APPS values.
- Perform the POWERTRAIN VERIFICATION TEST. Verification Tests.

No

- Go To 9

9. PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Verification Tests.

No

- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Verification Tests.

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