LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Suzuki >> 2005 >> Aerio LX, AWD >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine General Information And Diagnosis >> DTC P0121: Throttle Position Sensor Circuit Range/Performance >> Diagnostic Trouble Codes Troubleshooting
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Trouble Codes Troubleshooting

DTC TROUBLESHOOTING

Step Action Yes No
1 Was "Engine and Emission Control System Check" performed?  Go to Step 2. Go to "ENGINE AND EMISSION CONTROL SYSTEM CHECK :".
2 Do you have SUZUKI scan tool?  Go to Step 3. Go to Step 4.
3 Check TP sensor and its circuit 
  1. Turn OFF ignition switch and connect SUZUKI scan tool to DLC.
  2. Turn ON ignition switch and check TP sensor output voltage when throttle valve is at idle position and fully opened.
G04013701

Does voltage vary within specified value linearly as shown in the graph? 		 Go to Step 13. Go to Step 5.
4 Check TP sensor circuit check 
  1. Disconnect connectors from ECM with ignition switch turned OFF.
  2. Remove ECM from vehicle body and connect connectors from ECM.
  3. Check for proper connection to "C46-22" terminal of ECM connector.
  4. If OK, connect voltmeter positive (+) terminal to "C46-22" terminal (1) of ECM connector and voltmeter negative (-) terminal to "C46-16" terminal (2) of ECM connector.
    Fig 1: Connecting Voltmeter Of ECM Connector
    G04013702Courtesy of SUZUKI OF AMERICA CORP.
  5. Check TP sensor output voltage when throttle valve is at idle position and fully opened.
G04013702G04013703Courtesy of SUZUKI OF AMERICA CORP.

Does voltage vary within specified value linearly as shown in the graph? 		 Go to Step 13. Go to Step 5.
5 Check TP sensor voltage 
  1. Disconnect connector from TP sensor with ignition switch turned OFF.
  2. Check for proper connection to TP sensor connector at "GRY/RED", "GRY/BLU" and "ORN" wire terminals.
  3. If OK, then with ignition switch turned ON, check TP sensor connector voltage between each terminal of "GRY/RED" wire, "GRY/BLU" wire and engine ground.

Is voltage about 4-6 V at each terminal? 		 Go to Step 9. Go to Step 6.
6 Check ECM voltage 
  1. Check for proper connection of ECM connector at "C46-23" and "C46-22" terminals.
  2. If OK, disconnect connectors from MAP sensor and fuel tank pressure and temp, sensor.
  3. Turn ON ignition switch, check voltage of ECM connector between each terminal of "C46-23", "C46-22" and body ground.

Is voltage about 4- 6 V at each terminal? 		 Open or high resistance wire in "GRY/RED" and/ or "GRY/BLU" circuit.
Faulty MAP sensor and fuel tank pressure and temp, sensor, check MAP sensor and fuel tank pressure and temp, sensor according to MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR INSPECTION and FUEL TANK PRESSURE AND TEMP. SENSOR INSPECTION .
If they are OK, go to Step 7.		 Go to Step 7.
7 Check wire circuit 
  1. Disconnect connectors from ECM with ignition switch turned OFF.
  2. Measure resistance of TP sensor connector between each terminal of "GRY/RED" wire, "GRY/BLU" wire terminal and body ground.

Is resistance infinity? 		 Go to Step 8. "GRY/RED" and/or "GRY/BLU" wire shorted to ground circuit.
If wire are OK, substitute a known-good ECM and recheck.
8 Check wire circuit 
  1. Turn ignition switch to ON position.
  2. Check voltage of TP sensor connector between each terminal of "GRY/RED" wire, "GRY/BLU" wire and body ground.

Is voltage about 0 V at each terminal? 		 Go to Step 9. "GRY/RED" and/or "GRY/BLU" wire shorted to power circuit.
If wire are OK, substitute a known-good ECM and recheck.
9 Check wire circuit 
  1. Measure resistance between "C46-22" terminal of ECM connector and "GRY/BLU" wire terminal of TP sensor connector with ignition switch turned OFF.

Is resistance below 5 Ω? 		 Go to Step 10. High resistance wire in "GRY/BLU" circuit.
10 Check ground circuit 
  1. Connect connectors to ECM.
  2. Measure resistance between "ORN" wire terminal of TP sensor connector and body ground.

Is resistance below 10 Ω? 		 Go to Step 12. Go to Step 11.
11 Check ground circuit 
  1. Disconnect connectors from ECM with ignition switch turned OFF.
  2. Remove ECM from vehicle body and connect connectors to ECM.
  3. Measure resistance between "C46-16" terminal of ECM connector and body ground.

Is resistance below 5 Ω? 		 Open or high resistance wire in "ORN" circuit. Poor "C46-16" connection. Open or high resistance wire in "C45-6" and/or "C46-6" circuit.
If circuit are OK, substitute a known-good ECM and recheck.
12 Check TP sensor 
  1. Turn ignition switch to OFF position.
  2. Disconnect TP sensor connector.
  3. 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 kΩ Between 1 and 2: 0.1 - 6.5 kΩ, varying according to throttle valve opening. 
    Fig 2: Measuring Resistance Between Terminals
    G04013704Courtesy of SUZUKI OF AMERICA CORP.

Are measured values as specified? 		 Go to Step 13. Replace TP sensor.
13 Check for MAF and IAT sensor performance 
  1. Check MAF sensor performance, referring to "DTC P0101: MASS AIR FLOW CIRCUIT RANGE / PERFORMANCE PROBLEM :".

Is it in good condition? 		 Go to Step 14. Repair or replace it.
14 Check throttle body 
  1. Check throttle body for clog or leak.

Is it OK? 		 Substitute a known-good ECM and recheck. Repair throttle body.
scientia non olet · About LEMON Manuals