P0121

DTC P0121: Throttle Position Circuit Range / Performance Problem

Wiring Diagram










DTC Detecting Condition and Trouble Area






DTC Confirmation Procedure

WARNING:

- When performing a road test, select a place where there is no traffic or possibility of a traffic accident and very careful during testing to avoid occurrence of an accident.
- Road test should be carried out with 2 persons, a driver and a tester, on a level road.

NOTE:

Check to make sure that the following conditions are satisfied when using this DTC confirmation procedure.

- Intake air temp.: -14 °C, 6.8 °F or higher
- Altitude (barometric pressure): 2020 m, 6650 ft or less (540 mmHg, 72 kPa or more)

1) With ignition switch turned OFF, connect scan tool.
2) Turn ON ignition switch and clear DTC using scan tool.
3) Start engine and warm up to normal operating temperature.
4) Drive vehicle at 40 mph (60 km/h) or higher for 5 min. or more.
5) Stop vehicle and run engine at idle speed for 10 sec.
6) Check DTC and pending DTC.

DTC Troubleshooting

1.
Was "Engine System Check" performed?
YES
Go to Step 2.
NO
Go to Engine System Check Engine System Check.

2. Check TP sensor and its circuit.

Turn OFF ignition switch and connect SUZUKI scan tool to DLC.
Turn ON ignition switch and check TP sensor output voltage when throttle valve is at idle position and fully opened.






Does voltage vary within specified value linearly as shown in figure?
YES
Go to Step 12.
NO
Go to Step 3.

3. Check TP sensor voltage.

Disconnect connector from TP sensor with ignition switch turned OFF.
Check proper connection to TP sensor at "GRY/RED", "GRY/BLU" and "ORN".
If OK, then with ignition switch turned ON, check voltage at each of "GRY/RED", "GRY/BLU" wire terminals.

Is voltage about 4 - 6 V at each terminal?
YES
Go to Step 7.
NO
Go to Step 4.

4. Check ECM voltage.

Check proper connection of connector at "C46-18" and "C46-25" wire terminals.
If OK, disconnect connector from MAP sensor.
Turn ON ignition switch, check voltage between "C46-18" and body ground and between "C46-25" and body ground.

Is voltage about 4 - 6 V at each terminal?
YES
"GRY/RED" and/or "GRY/BLU" wire open or high resistance circuit.
Faulty MAP sensor, check MAP sensor according to Testing and Inspection Manifold Absolute Pressure (MAP) Sensor Inspection.
If they are OK, go to Step 5.
NO
Go to Step 5.

5. Check wire circuit.

Disconnect connector from ECM with ignition switch turned OFF.
Measure resistance between "GRY/RED" wire terminal and body ground and between "GRY/BLU" wire terminal and body ground.

Is resistance infinity?
YES
Go to Step 6.
NO
"GRY/RED" and/or "GRY/BLU" wire shorted to ground circuit.
If wire are OK, substitute a known-good ECM and recheck.

6. Check wire circuit.

Turn ON ignition switch.
Check voltage between "GRY/RED" wire terminal and body ground and between "GRY/BLU" wire terminal and body ground.

Is voltage about 0 V at each terminal?
YES
Go to Step 7.
NO
"GRY/RED" and/or "GRY/BLU" wire shorted to power circuit.
If wire are OK, substitute a known-good ECM and recheck.

7. Check wire circuit.

Measure resistance between "C46-25" terminal and "GRY/BLU" wire terminal in TP sensor connector with ignition switch turned OFF.

Is resistance below 5 ohms?
YES
Go to Step 8.
NO
"GRY/BLU" wire in high resistance circuit.

8. Check ground circuit.

Connect connector to ECM.
Check proper connection of MAP sensor at "ORN" wire terminal.
Measure resistance between "ORN" wire terminal in MAP sensor connector and body ground.

Is resistance below 10 ohms?
YES
Go to Step 10.
NO
Go to Step 9.

9. Check ground circuit.

Measure resistance between "C46-27" terminal and body ground.

Is resistance below 5 ohms?
YES
"ORN" wire open circuit or high resistance circuit.
Poor "C46-27" connection.
NO
Faulty ECM ground circuit.
If circuit are OK, substitute a known-good ECM and recheck.

10. Throttle position sensor installation check.

Adjust TP sensor installation position referring to Adjustments Throttle Position (TP) Sensor Adjustment.
Check TP sensor output voltage in the same procedure as Step 2.

Is check result as specified?
YES
Throttle position sensor maladjusted.
NO
Go to Step 11.

11. Check TP sensor.

Turn OFF ignition switch.
Disconnect TP sensor connector.
Check for proper connection to TP sensor at each terminal.
If OK, then measure resistance between terminals and check if each measured value is as specified in the following.

TP sensor resistance
Between 1 and 3: 4.0 - 6.0 kohms
Between 1 and 2: 0.1 - 6.5 kohms, varying according to throttle valve opening.





Are measured values as specified?
YES
Go to Step 12.
NO
Replace TP sensor.

12. Check MAF sensor for performance.

Check MAF sensor performance, referring to DTC P0101 Diagnosis Flow.

Is it in good condition?
YES
Go to Step 13.
NO
Repair or replace it.

13. Check throttle body.

Check throttle body for clog or leak.

Is it OK?
YES
Substitute a known-good ECM and recheck.
NO
Repair throttle body.