P0122
P0122-THROTTLE POSITION SENSOR 1 CIRCUIT LOW
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
The Electronic Throttle Control (ETC) system uses two Throttle Position Sensors (TPS) to monitor the throttle blade position. The TPS Sensors 1 and 2 are located within the throttle body assembly. Each sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. Processors are also used to monitor the ETC system data. The processors are located within the Powertrain Control Module (PCM). Each signal circuit provides the processors with a signal voltage proportional to throttle blade movement. The processors share and monitor data to verify that the indicated TPS calculation is correct.
- When Monitored:
With the ignition on. Battery voltage greater than 10.0 volts.
- Set Condition:
Throttle Position Sensor (TPS) voltage at the Powertrain Control Module (PCM) is less than 0.16 volt for 0.7 second. One Trip Fault. Three good trips to turn off the MIL. ETC light will illuminate.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
Diagnostic Test
1. ACTIVE DTC
NOTE: Diagnose and repair any Throttle Body circuit, system voltage or sensor supply voltage DTCs before continuing with this test.
1. Turn the ignition on.
2. With the scan tool, read the active DTCs.
NOTE: If the DTC does not reset it may be necessary to test drive the vehicle.
NOTE: If the P2122-APP Sensor 1 Circuit Low DTC is also Active, diagnose the P2122 before continuing with the P0122 diagnostic procedure.
Is the DTC Active at this time?
Yes
- Go To 2
No
- Go To 11
2. P0222 ALSO SET
Was the P0222-TPS 2 VOLTAGE LOW DTC set along with the P0122?
Yes
- Go To 3
No
- Go To 4
3. CHECK THE (F855) 5-VOLT SUPPLY CIRCUIT
1. Turn the ignition off.
2. Disconnect the Throttle Body harness connector.
3. Ignition on, engine not running.
4. Measure the voltage on the (F855) 5-Volt Supply circuit in the Throttle Body harness connector.
Is the voltage between 4.8 to 5.2 volts?
Yes
- Go To 4
No
- Go To 8
4. THROTTLE POSITION SENSOR
1. With the scan tool, monitor the TPS 1 voltage with the Sensor harness connector disconnected.
NOTE: The sensor voltage should be approximately 5.0 volts (plus or minus.1 volt) with the connector disconnected.
Does the scan tool display the voltage as described above?
Yes
- Verify that there is good pin to terminal contact in the Throttle Body and Powertrain Control Module connectors. If OK, replace the Throttle Body Assembly. Disconnect the Battery when replacing the Throttle Body Assembly. After installation is complete, using a scan tool select the ETC RELEARN function. Throttle Body - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 5
5. CHECK THE (K22) TPS 1 SIGNAL CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
3. Measure the resistance between ground and the (K22) TPS 1 Signal circuit at the Throttle Body harness connector.
Is the resistance above 10k Ohms?
Yes
- Go To 6
No
- Repair the short to ground in the (K22) TPS 1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
6. CHECK FOR THE (K22) TPS 1 SIGNAL CIRCUIT SHORTED TO THE (K922) TPS RETURN CIRCUIT
1. Measure the resistance between the (K22) TPS 1 Signal circuit and the (K922) TPS Return circuit in the Throttle Body harness connector.
Is the resistance above 10k Ohms?
Yes
- Go To 7
No
- Repair the short between the (K922) TPS Return circuit and the (K22) TPS 1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
7. CHECK THE (K22) TPS 1 SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K22) TPS 1 Signal circuit between the Throttle Body harness connector to the PCM C2 harness connector.
Is the resistance below 5.0 Ohms?
Yes
- Go To 10
No
- Repair the (K22) TPS 1 Signal circuit for an open circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
8. (F855) 5-VOLT SUPPLY CIRCUIT OPEN
1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
3. Measure the resistance of the (F855) 5-Volt Supply circuit from the Throttle Body harness connector to the PCM C2 harness connector.
Is the resistance below 5.0 Ohms?
Yes
- Go To 9
No
- Repair the open in the (F855) 5-Volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
9. CHECK THE (F855) 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO GROUND
1. Measure the resistance between ground and the (F855) 5-Volt Supply circuit in the Throttle Body harness connector.
Is the resistance above 10k Ohms?
Yes
- Go To 10
No
- Repair the short to ground in the (F855) 5-Volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
10. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Throttle Body and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Throttle Body and Powertrain Control Module connectors.
4. Perform any Technical Service Bulletins that may apply.
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 (PCM). Powertrain Control Module - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
11. THROTTLE FOLLOWER TEST
1. With the scan tool, perform the ETC Throttle Follower Test.
2. Monitor the TPS 1 voltage.
Does the voltage start at approximately 0.7 volt and increase to approximately 4.3 volts with a smooth transition?
Yes
- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.
No
- Verify that there is good pin to terminal contact in the Throttle Body and Powertrain Control Module connectors. If OK, replace the Throttle Body Assembly. Disconnect the Battery when replacing the Throttle Body Assembly. After installation is complete, using a scan tool select the ETC RELEARN function. Throttle Body - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.