Electronic Throttle Control Motor Performance
P0120 - ELECTRONIC THROTTLE CONTROL MOTOR PERFORMANCE
When Monitored and Set Condition
- When Monitored: Ignition on with no MAP Sensor DTCs set.
- Set Condition: TP Sensor signals in the Throttle Body do not correlate to the MAP Sensor signal.
Diagnostic Test
1. PRE-DIAGNOSTIC CHECK OUT
NOTE: Always perform diagnostics with a fully charged battery.
NOTE: Check connectors - Clean/repair as necessary. Poor pin to terminal connections can set DTCs.
NOTE: Check for applicable TSBs related to the problem.
Turn the ignition on.
With the DRB III(R), read PCM DTCs.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors. Repair as necessary.
Perform this procedure prior to symptom diagnosis.
Continue
- Go To 2
2. CHECK FOR CURRENT DTC
NOTE: Diagnose any other Throttle Body DTC(s) before continuing.
NOTE: The throttle plate should be free from binding and carbon build up.
NOTE: Ensure the throttle plate is at the idle position.
NOTE: Inspect the engine for vacuum leaks.
NOTE: If the PCM detects and stores a DTC, the PCM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the DRB III(R) at the same time the DTC is displayed.
NOTE: Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for a DTC.
Turn the ignition on.
With the DRB III(R), erase PCM DTCs.
NOTE: It maybe necessary to road test the vehicle for this DTC to set.
With the DRB III(R), read PCM DTCs.
Did this DTC set again?
Yes
- Go To 3
- If DTC P0121 APPS 5 volt SUPPLY CIRCUIT is present with this DTC, Go To 10
No
- Go To 25
3. CHECK FOR THROTTLE PLATE BINDING, STICKING, OR OBSTRUCTION
Turn the ignition off.
Remove the MAF Sensor.
Open and close the throttle plate fully by hand to ensure there is not a binding or sticking condition and that there is nothing obstructing it from opening.
Did the throttle plate open and close freely?
Yes
- Go To 4
No
- Repair the condition or replace the Throttle Body.
4. CHECK THE TP SENSOR SIGNAL CIRCUITS
Turn the ignition off.
Disconnect the Throttle Body harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Turn the ignition on.
With the DRB III(R), monitor the TP 1 and TP 2 voltages.
Connect a jumper wire between the Sensor Ground circuit and the TP Sensor Signal 1 circuit at the Throttle Body harness connector.
TP Sensor 1 voltage should change from approximately 5 volts to 0.5 volt?
For TP Sensor 2, connect a jumper wire between the 5-volt Supply circuit and the TP Sensor Signal 2 circuit at the Throttle Body harness connector.
TP Sensor 2 voltage should change from approximately 0 volts to 5.0 volts?
NOTE: Remove the jumper wire before continuing.
Are the TP 1 and TP 2 voltage readings within the listed specifications?
Yes
- Go To 5
No
- Go To 10
5. MEASURE THE VOLTAGE OF THE THROTTLE CONTROL MOTOR CIRCUITS
With the ignition on.
Measure the voltage of the Throttle Control Motor 1 and the Throttle Control Motor 2 circuits at the Throttle Body harness connector.
Is the voltage between 3.1 and 3.5 volts on both circuits?
Yes
- Replace the Throttle Body.
No
- If the voltage is above 3.5 volts, Go To 6
- If the voltage is below 3.1 volts, Go To 7
6. CHECK THROTTLE CONTROL MOTOR CIRCUITS FOR SHORT TO VOLTAGE
Turn the ignition off.
Disconnect the PCM C1 harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Turn the ignition on.
Measure the voltage of the Throttle Control Motor circuit(s) that measured above 3.5 volts in the previous step.
Is the voltage below 1.0 volt?
Yes
- Go To 24
No
- Repair the Throttle Control Motor circuit(s) for a short to voltage.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
7. CHECK THE THROTTLE CONTROL MOTOR CIRCUITS FOR A SHORT TO GROUND
Turn the ignition off.
Disconnect the PCM C1 harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between ground and the Throttle Control Motor circuit(s) that measured below 3.1 volts in the previous step.
Is the resistance above 100 kohms?
Yes
- Go To 8
No
- Repair the Throttle Control Motor circuit(s) for a short to ground.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
8. CHECK THROTTLE CONTROL MOTOR CIRCUITS FOR A SHORT TO SENSOR GROUND CIRCUIT
With the ignition off.
Measure the resistance between the Sensor Ground circuit and the Throttle Control Motor circuit(s) that measured below 3.1 volts.
Is the resistance above 100 kohms?
Yes
- Go To 9
No
- Repair the Throttle Control Motor circuit(s) for a short to the Sensor Ground circuit.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
9. THROTTLE CONTROL MOTOR CIRCUIT(S) OPEN
With the ignition off.
Measure the resistance of the Throttle Control Motor 1 circuit from the Throttle Body harness connector to the PCM C1 harness connector.
Measure the resistance of the Throttle Control Motor 2 circuit from the Throttle Body harness connector to the PCM C1 harness connector.
Is the resistance below 5.0 ohms for both measurements?
Yes
- Go To 24
When Monitored and Set Condition
- Repair the Throttle Control Motor circuit(s) that measured above 5.0 ohms for an open.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
10. CHECK THE 5-volt SUPPLY CIRCUIT VOLTAGE
With the ignition on.
Measure the voltage of the 5-volt Supply circuit at the Throttle Body harness connector.
Is the voltage between 4.7 and 5.2 volts?
Yes
- Go To 11
No
- If the voltage is above 5.2 volts, Go To 16
- If the voltage is below 4.7 volts, Go To 18
11. CHECK THE SENSOR GROUND CIRCUIT
Turn the ignition off.
Measure the resistance between ground and the Sensor Ground circuit at the Throttle Body harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go To 12
No
- Go To 23
12. TP SENSOR SIGNAL CIRCUIT(S) SHORT TO VOLTAGE
With the ignition off.
Disconnect the PCM C3 harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Turn the ignition on.
Measure the voltage on the TP Sensor Signal 1 and the TP Sensor Signal 2 circuits at the Throttle Body harness connector.
Is the voltage below 1.0 volt?
Yes
- Go To 13
No
- Repair the TP Sensor Signal circuit(s) for a short to voltage.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
13. CHECK THE TP SENSOR SIGNAL CIRCUITS FOR A SHORT TO OTHER CIRCUITS
Turn the ignition off.
Measure the resistance between the TP Sensor Signal 1 circuit and all other circuits in the Throttle Body harness connector.
Measure the resistance between the TP Sensor Signal 2 circuit and all other circuits in the Throttle Body harness connector.
Is the resistance above 100 kohms for all measurements?
Yes
- Go To 14
No
- Repair the circuits that measured below 100 kohms for a short together.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
14. TP SENSOR SIGNAL CIRCUIT(S) OPEN
With the ignition off.
Measure the resistance of the TP Sensor Signal 1 circuit from the Throttle Body harness connector to the PCM C3 harness connector.
Measure the resistance of the TP Sensor Signal 2 circuit from the Throttle Body harness connector to the PCM C3 harness connector.
Is the resistance below 5.0 ohms for both measurements?
Yes
- Go To 15
No
- Repair the TP Sensor Signal circuit(s) for an open.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
15. MEASURE THE RESISTANCE BETWEEN GROUND AND THE TP SENSOR SIGNAL CIRCUITS
With the ignition off.
Measure the resistance between ground and the TP Sensor Signal 1 circuit at the Throttle Body harness connector.
Measure the resistance between ground and the TP Sensor Signal 2 circuit at the Throttle Body harness connector.
Is the resistance above 100 kohms for both measurements?
Yes
- Go To 24
No
- Repair the TP Sensor Signal circuit(s) for a short to ground.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
16. CHECK THE 5-volt SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE
Turn the ignition off.
Disconnect the PCM C3 harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Turn the ignition on.
Measure the voltage of the 5-volt Supply circuit at the Throttle Body harness connector.
Is the voltage below 1.0 volt?
Yes
- Go To 17
No
- Repair the 5-volt Supply circuit for a short to voltage.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
17. CHECK THE APP SENSOR 5-volt SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE
Turn the ignition off.
Disconnect the PCM C4 harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Turn the ignition on.
Measure the voltage of the APP Sensor 5-volt Supply circuit at the PCM C4 harness connector.
Is the voltage below 1.0 volt?
Yes
- Go To 24
No
- Repair the APP Sensor 5-volt Supply circuit for a short to voltage.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
18. MEASURE THE RESISTANCE BETWEEN GROUND AND THE 5-volt SUPPLY CIRCUIT
Turn the ignition off.
Disconnect the PCM C3 harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between ground and the 5-volt Supply circuit.
Is the resistance above 100 kohms?
Yes
- Go To 19
No
- Repair the 5-volt Supply circuit for a short to ground.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
19. MEASURE RESISTANCE BETWEEN THE 5-volt SUPPLY CIRCUIT AND SENSOR GROUND CIRCUITS
With the ignition off.
Measure the resistance between the 5-volt Supply circuit and all Sensor Ground circuits in the PCM C3 harness connector.
Is the resistance above 100 kohms for all measurements?
Yes
- Go To 20
No
- Repair the 5-volt Supply circuit for a short to the Sensor Ground circuit that measured below 100 kohms.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
20. MEASURE THE RESISTANCE BETWEEN GROUND AND THE APP SENSOR 5-volt SUPPLY CIRCUIT
With the ignition off.
Disconnect the PCM C4 harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between ground and the APP Sensor 5-volt Supply circuit at the PCM C4 harness connector.
Is the resistance above 100 kohms?
Yes
- Go To 21
No
- Repair the APP Sensor 5-volt Supply circuit for a short to ground.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
21. MEASURE RESISTANCE BETWEEN THE APP SENSOR 5-volt SUPPLY CIRCUIT AND SENSOR GROUND CIRCUITS
With the ignition off.
Measure the resistance between the APP Sensor 5-volt Supply circuit and all Sensor Ground circuits in the PCM C4 harness connector.
Is the resistance above 100 kohms for all measurements?
Yes
- Go To 22
No
- Repair the APP Sensor 5-volt Supply circuit for a short to the Sensor Ground circuit that measured below 100 kohms.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
22. 5-volt SUPPLY CIRCUIT OPEN
With the ignition off.
Measure the resistance of the 5-volt Supply circuit from the Throttle Body harness connector to the PCM C3 harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go To 24
No
- Repair the 5-volt Supply circuit for an open.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
23. SENSOR GROUND CIRCUIT OPEN
With the ignition off.
Disconnect the PCM C3 harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance of the Sensor Ground circuit from the Throttle Body harness connector to the PCM C3 harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go To 24
No
- Repair the Sensor Ground circuit for an open.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
24. 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.
If there are no possible causes remaining, review repair.
Repair
- Replace and program the Powertrain Control Module.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
25. TP SENSOR SWEEP
With the ignition on.
With the DRB III(R), monitor the TP 1 and TP 2 voltages.
Slowly depress the Accelerator Pedal from the idle position to the wide open throttle position.
The voltage for TP Sensor 1 should start at approximately 0.75 volt and increase to above 1.3 volts.
The voltage for TP Sensor 2 should start at approximately 4.2 volts and decrease to approximately 3.6 volts.
Are the voltages within the range specified for the appropriate TP Sensor?
Yes
- Go To 26
No
- Replace the Throttle Body.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
26. INTERMITTENT WIRING AND CONNECTORS
The condition that caused this DTC to set is currently not present. Inspect the related wiring harness for a possible intermittent condition.
NOTE: Check connectors - Clean/repair as necessary. Poor pin to terminal connections can set DTCs.
NOTE: Check for any Technical Service Bulletins that may apply.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors specific to this DTC. Wiggle the wires while checking for shorts and open circuits.
Were there any problems found?
Yes
- Repair as necessary.
- Perform POWERTRAIN VERIFICATION TEST - VER 2. Powertrain Verification Test - Ver 2
No
- The condition that caused this DTC to set is currently not present. Inspect the related wiring harness for a possible intermittent condition.