P2120-ACC PEDAL POSITION SENSOR 1 CKT SIGNAL VOLTAGE TOO HIGH
When Monitored: With the ignition on.
Set Condition: The ECM detects voltage on the Accelerator Pedal Position Sensor Signal
circuit above 4.5 volts.
P2120-ACC PEDAL POSITION SENSOR 1 CKT SIGNAL VOLTAGE TOO LOW
When Monitored: With the ignition on.
Set Condition: The ECM detects voltage on the Accelerator Pedal Position Sensor Signal
circuit 0.0 volt.
P2120-ACC PEDAL POSITION SENSOR 1 CKT SUPPLY VOLTAGE TOO HIGH OR
LOW
When Monitored: With the ignition on.
Set Condition: The Accelerator Pedal Position Sensor 5-Volt Supply voltage is too high or
too low.
POSSIBLE CAUSES
APP SENSOR IDLE VOLTAGE
APP SENSOR WIDE OPEN THROTTLE VOLTAGE
ECM - 5-VOLT SUPPLY CIRCUIT
LOW IDLE POSITION SWITCH SENSE CIRCUIT SHORTED TO GROUND
SENSOR GROUND OPEN (APP SENSOR)
SENSOR GROUND OPEN (IDLE SWITCH)
INTERMITTENT CONDITION
5-VOLT SUPPLY CIRCUIT OPEN
APP SENSOR SIGNAL CIRCUIT OPEN
LOW IDLE POSITION SWITCH SENSE CIRCUIT OPEN
5-VOLT SUPPLY CIRCUIT SHORTED TO THE SENSOR GROUND CIRCUIT
VERIFY LOW IDLE POSITION SWITCH OPERATION
APP SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
VERIFY APP SENSOR OPERATION
APP SENSOR SIGNAL CIRCUIT SHORTED TO THE SENSOR GROUND CIRCUIT
LOW IDLE POSITION SWITCH SENSE CIRCUIT SHORTED TO THE SENSOR GROUND CIR-
CUIT
5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
ECM - SENSOR GROUND OPEN
APP SENSOR CIRCUIT SHORTED TO VOLTAGE
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P2120-ACC PEDAL POSITION SENSOR 1 CKT PLAUSIBILITY ÐContinued
POSSIBLE CAUSES
APP SENSOR GROUND CIRCUIT SHORTED TO VOLTAGE
LOW IDLE POSITION SWITCH SENSE CIRCUIT SHORTED TO VOLTAGE
LOW IDLE POSITION SWITCH SENSE GROUND CIRCUIT SHORTED TO VOLTAGE
VERIFY CORRECT SWITCHING
ECM - APP SENSOR SIGNAL CIRCUIT
TEST ACTION APPLICABILITY
1NOTE: The brake switch must be operational for the result of this test to be
valid.
Turn the ignition off.
Disconnect the APP Sensor harness connector.
Connect one end of a jumper wire to the Low Idle Position Sense circuit at the APP
Sensor harness connector.
Turn the ignition on.
With the DRB III, monitor the Low Idle Position Switch input while tapping the other
end of the jumper wire to the Sensor Ground circuit at the APP Sensor harness
connector.
Does the DRB III change between IDLE and ABOVE IDLE when tapping the jumper
wire?All
Ye s®Go To 2
No®Go To 20
2 Turn the ignition on.
With the DRB III observe the Low Idle Position Switch input.
Press and release the accelerator pedal several times while observing the DRB III
display.
NOTE: The Low Idle Position Switch input should change from IDLE to
ABOVE IDLE when pressing and releasing the accelerator pedal.
Did Low Idle Position Switch input change between IDLE and ABOVE IDLE?All
Ye s®Go To 3
No®Replace the Accelerator Pedal Position Sensor in accordance with
the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
3NOTE: If DTC P0641 or P0651 is present with this DTC, diagnose DTCs
P0641 and P0651 before diagnosing this DTC.
Turn the ignition off.
Disconnect the APP Sensor harness connector.
Turn the ignition on.
Measure the voltage of the 5-volt Supply circuit in APP Sensor harness connector.
Is the voltage between 4.7 and 5.3 volts?All
Ye s®Go To 4
No®Go To 16
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TEST ACTION APPLICABILITY
4 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Connect a jumper wire between APP Sensor Signal circuit and the 5-volt supply
circuit at the APP Sensor harness connector .
With the DRBIII, read the PEDAL OUTPUT VOLTS.
Does the DRBIII display between 4.0 and 5.5 volts?All
Ye s®Go To 5
No®Go To 12
5 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Remove the ECM/PCM Relay from the PDC.
Connect a jumper wire between cavity 30 and cavity 87 ECM/PCM Relay connector.
Turn the ignition on.
Measure the voltage of the APP Sensor Ground circuit.
Is the voltage above 1.0 volt?All
Ye s®Repair the App Sensor Ground circuit for a short to voltage.
Perform ROAD TEST VERIFICATION - VER-2.
No®Go To 6
6 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Measure the resistance of the Sensor Ground circuit between the APP Sensor and the
ECM.
Is the resistance below 10.0 ohms?All
Ye s®Go To 7
No®Repair the APP Sensor Ground circuit for an open.
Perform ROAD TEST VERIFICATION - VER-2.
7 Turn the ignition on.
With the DRB III, read the PEDAL OUTPUT VOLTS with the accelerator pedal in
the at rest position.
Does the DRB III display between 0.28 and 0.38 volt?All
Ye s®Go To 8
No®Replace the Accelerator Pedal Position Sensor in accordance with
the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
8 Turn the ignition on.
Fully depress the accelerator pedal.
With the DRBIII, read the PEDAL OUTPUT VOLTS.
Does the DRB III display between 4.1 and 4.6 volts?All
Ye s®Go To 9
No®Replace the Accelerator Pedal Position Sensor in accordance with
the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
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P2120-ACC PEDAL POSITION SENSOR 1 CKT PLAUSIBILITY ÐContinued
TEST ACTION APPLICABILITY
9 Turn the ignition on.
With the DRB III, read the PEDAL OUTPUT VOLTS.
With the accelerator pedal in the idle position, slowly depress the accelerator pedal
until the pedal is fully depressed.
NOTE: The PEDAL OUTPUT VOLTS should increase smoothly as the pedal
is depressed.
Does the voltage increase smoothly with the accelerator pedal travel?All
Ye s®Go To 10
No®Replace the Accelerator Pedal Position Sensor in accordance with
the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
10 Turn the ignition on.
With the DRB III, select Engine and with the custom display feature select Low Idle
Switch input and the Accel Pedal %.
Slowly depress and release the accelerator pedal several times while monitoring the
DRB III display.
NOTE: The Low Idle Switch state should change between 5% and 10% of
Accelerator Pedal position.
Did the Low Idle Switch state change between 5% and 10% of Accelerator Pedal
position?All
Ye s®Go To 11
No®Replace the Accelerator Pedal Position Sensor.
Perform ROAD TEST VERIFICATION - VER-2.
11WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
NOTE: The conditions that set the DTC are not present at this time. The
following list may help in identifying the intermittent condition.
With the engine running and at normal operating temperature, monitor the DRB
parameters related to the DTC while wiggling the wiring harness. Look for param-
eter values to change and/or a DTC to set.
Review the DTC When Monitored and Set Conditions. If possible, try to duplicate the
conditions under which the DTC was set.
Refer to any Technical Service Bulletins (TSB) that may apply.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Were any of the above conditions present?All
Ye s®Repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No®Test Complete.
12 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Measure the resistance of the APP Sensor Signal circuit.
Is the resistance below 10.0 ohms?All
Ye s®Go To 13
No®Repair the APP Sensor Signal circuit for an open
Perform ROAD TEST VERIFICATION - VER-2.
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P2120-ACC PEDAL POSITION SENSOR 1 CKT PLAUSIBILITY ÐContinued
TEST ACTION APPLICABILITY
13 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Measure the resistance between ground and the APP Sensor Signal circuit.
Is the resistance below 1000 ohms?All
Ye s®Repair the APP Sensor Signal circuit for a short to ground.
Perform ROAD TEST VERIFICATION - VER-2.
No®Go To 14
14 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Measure the resistance between the APP Sensor Signal circuit and the Sensor
Ground circuit at of the APP Sensor harness connector.
Is the resistance below 1000 ohms?All
Ye s®Repair the APP Sensor Signal and Sensor Ground circuits for a
short together.
Perform ROAD TEST VERIFICATION - VER-2.
No®Go To 15
15 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Remove the ECM/PCM Relay from the PDC.
Connect a jumper wire between cavity 30 and cavity 87 of the ECM/PCM Relay
connector.
Turn the ignition on.
Measure the voltage of the APP Sensor Signal circuit.
Is the voltage above 1.0 volt?All
Ye s®Repair the APP Sensor Signal circuit for a short to voltage.
Perform ROAD TEST VERIFICATION - VER-2.
No®Replace and program the Engine Control Module in accordance
with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
16 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Measure the resistance of the 5-volt Supply circuit.
Is the resistance below 10.0 ohms?All
Ye s®Go To 17
No®Repair the 5-volt Supply circuit for an open.
Perform ROAD TEST VERIFICATION - VER-2.
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P2120-ACC PEDAL POSITION SENSOR 1 CKT PLAUSIBILITY ÐContinued
TEST ACTION APPLICABILITY
17 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Measure the resistance between the 5-volt Supply circuit and the Sensor Ground
circuit at the APP Sensor harness connector.
Is the resistance above 1000 ohms for both of the measurements?All
Ye s®Go To 18
No®Repair the 5-volt Supply circuit for a short to the Sensor Ground
circuit.
Perform ROAD TEST VERIFICATION - VER-2.
18 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Measure the resistance between ground and the 5-volt Supply circuit.
Is the resistance below 1000 ohms?All
Ye s®Repair the 5-volt Supply circuit for a short to ground.
Perform ROAD TEST VERIFICATION - VER-2.
No®Go To 19
19 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Remove the ECM/PCM Relay from the PDC.
Connect a jumper wire between cavity 30 and cavity 87 of the ECM/PCM Relay
connector.
Turn the ignition on.
Measure the voltage of the 5-volt Supply circuit in the ECM harness connector.
Is the voltage above 1.0 volt?All
Ye s®Repair the 5-volt Supply circuit for a short to voltage.
Perform ROAD TEST VERIFICATION - VER-2.
No®Replace and program the Engine Control Module in accordance
with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
20 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Measure the resistance of the Low Idle Position Switch Sense circuit.
Is the resistance below 10.0 ohms?All
Ye s®Go To 21
No®Repair the Low Idle Position Switch Sense circuit for an open.
Perform ROAD TEST VERIFICATION - VER-2.
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P2120-ACC PEDAL POSITION SENSOR 1 CKT PLAUSIBILITY ÐContinued
TEST ACTION APPLICABILITY
21 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Measure the resistance between ground and the Low Idle Position Switch Sense
circuit.
Is the resistance above 1000 ohms?All
Ye s®Go To 22
No®Repair the Low Idle Position Switch Sense circuit for a short to
ground.
Perform ROAD TEST VERIFICATION - VER-2.
22 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Measure the resistance between the Low Idle Position Switch Sense circuit and the
Sensor Ground circuit at the APP Sensor harness connector.
Is the resistance above 1000 ohms?All
Ye s®Go To 23
No®Repair the Low Idle Position Switch Sense circuit and Sensor
Ground circuit for a short together.
Perform ROAD TEST VERIFICATION - VER-2.
23 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Remove the ECM/PCM Relay from the PDC.
Connect a jumper wire between cavity 30 and cavity 87 ECM/PCM Relay connector.
Turn the ignition on.
Measure the voltage of the Low Idle Position Switch Sense circuit.
Is the voltage above 1.0 volt?All
Ye s®Repair the Low Idle Position Switch Sense circuit for a short to
voltage.
Perform ROAD TEST VERIFICATION - VER-2.
No®Go To 24
24 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Remove the ECM/PCM Relay from the PDC.
Connect a jumper wire between cavity 30 and cavity 87 ECM/PCM Relay connector.
Turn the ignition on.
Measure the voltage of the Low Idle Position Switch Ground circuit.
Is the voltage above 1.0 volt?All
Ye s®Repair the Low Idle Position Switch Sense Ground circuit for a
short to voltage.
Perform ROAD TEST VERIFICATION - VER-2.
No®Go To 25
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P2120-ACC PEDAL POSITION SENSOR 1 CKT PLAUSIBILITY ÐContinued
TEST ACTION APPLICABILITY
25 Turn the ignition off.
Disconnect the APP Sensor harness connector.
Disconnect the ECM harness connectors.
Measure the resistance of the Low Idle Switch Sensor Ground circuit between the
APP Sensor and the ECM.
Is the resistance below 10.0 ohms?All
Ye s®Replace and program the Engine Control Module in accordance
with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
No®Repair the Low Idle Switch Sensor Ground circuit for an open.
Perform ROAD TEST VERIFICATION - VER-2.
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P2120-ACC PEDAL POSITION SENSOR 1 CKT PLAUSIBILITY ÐContinued