0872
0872-FAULT OF FUNCTION MONITOR IN ELECTRONIC ACCELERATOR
For a complete wiring diagram Consult Diagrams/Electrical
- When Monitored:
With the ignition on. No other APP DTCs set. No Sensor Reference Voltage DTC's set.
- Set Condition:
APP Sensor #1 and APP Sensor #2 signals do not agree for 0.36 seconds.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview
Theory of Operation
The Accelerator Pedal Position Sensor contains two independent 3 wire sensors. Each sensor provides independent pedal position signals to the PCM. The raw voltage signal from APP #1 sensor is 2 times the raw voltage signal from APP #2. Although the raw voltage signals differ, the scan tool converts and displays these voltages as matching percentages of pedal travel.
Diagnostic Test
1. ACTIVE DTC
Ignition on, engine not running.
With a scan tool, select View DTCs.
NOTE: Repair any other 5-Volt Supply or APPS High and Low DTCs before diagnosing 872.
Is the DTC Active at this time?
Yes
- Go To 2
No
- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. .
2. EXCESSIVE RESISTANCE IN THE (K23) APP SIGNAL 1 CIRCUIT
Turn the ignition off.
Disconnect the PCM 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.
Using a voltmeter perform a voltage drop test. Backprobe the (K23) APP Signal 1 circuit at the APPS harness connector and probe the appropriate terminal of the PCM harness connector. 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 (K23) APP Signal 1 circuit.
- Perform the Powertrain Verification Test. Powertrain Verification Test.
3. EXCESSIVE RESISTANCE IN THE (K4) APP SENSOR GROUND 1 CIRCUIT
Turn the ignition off.
Move the voltmeter leads to backprobe the (K4) APP Sensor Ground 1 circuit at the APPS harness connector and probe the appropriate terminal of the PCM harness connector. 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 (K4) APP Sensor Ground 1 circuit.
- Perform the Powertrain Verification Test. Powertrain Verification Test.
4. EXCESSIVE RESISTANCE IN THE (K29) APP SIGNAL 2 CIRCUIT
Turn the ignition off.
Move the voltmeter leads to backprobe the (K29) APP Signal 2 circuit at the APPS harness connector and probe the appropriate terminal of the PCM harness connector. 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 (K29) APP Signal 2 circuit.
- Perform the Powertrain Verification Test. Powertrain Verification Test.
5. EXCESSIVE RESISTANCE IN THE (K400) APP SENSOR GROUND 2 CIRCUIT
Turn the ignition off.
Move the voltmeter leads to backprobe the (K400) APP Sensor Ground 2 circuit at the APPS harness connector and probe the appropriate terminal of the PCM harness connector. 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 (K400) APP Sensor Ground 2 circuit.
- Perform the Powertrain Verification Test. Powertrain Verification Test.
6. EXCESSIVE RESISTANCE IN THE 5-VOLT SUPPLY CIRCUIT
Turn the Ignition off.
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 PCM harness connector. 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. Powertrain Verification Test.
7. EXCESSIVE RESISTANCE IN THE 5-VOLT SUPPLY CIRCUIT
Turn the Ignition off.
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 PCM harness connector. 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. Powertrain Verification Test.
8. CHECKING APPS NO.1 AND NO.2 WITH A LAB SCOPE
Turn the ignition off.
Set up a lab scope in a way that you can view two graphs simultaneously.
Ignition on, engine not running.
Backprobe (K23) APP Signal 1 circuit using Channel 1 at the APP Sensor harness connector.
Backprobe (K29) APP Signal 2 circuit using Channel 2 at the APP Sensor harness connector.
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. Powertrain Verification Test.
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. Powertrain Verification Test.
No
- Replace and program the Powertrain Control Module.
- Perform the Powertrain Verification Test. Powertrain Verification Test.