P0122-THROTTLE POSITION SENSOR 1 CIRCUIT LOW (ETC)
For a complete wiring diagram Refer to Section 8W.
- When Monitored:
With the ignition on. Battery voltage greater than 10 volts.
- Set Condition:
Throttle Position Sensor voltage at the PCM is less than 0.16 of a volt for 0.7 of a second. One Trip Fault. Three good trips to turn off the MIL. ETC light will illuminate.
| Possible Causes |
| (F855) 5-VOLT SUPPLY CIRCUIT OPEN |
| (F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND |
| (K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO GROUND |
| (K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO THE (K922) SENSOR RETURN CIRCUIT |
| THROTTLE POSITION SENSOR/THROTTLE BODY |
| PCM |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).
Diagnostic Test
1. ACTIVE DTCNOTE: If a 5-Volt Supply DTC has also set, diagnose the 5-Volt DTC before continuing.
NOTE: When this DTC is Active the engine speed, torque, and vehicle speed are limited to a Limp in mode.
Ignition on, engine not running.
With a scan tool, select View DTCs.
Is the DTC Active at this time?
Yes
- Go To 2
No
- Go To 10
2. P0222 ALSO SET
Was the P0222-TP SENSOR NO.2 VOLTAGE LOW DTC set along with the P0122?
Yes
- Go To 3
No
- Go To 4
3. (F855) 5-VOLT SUPPLY CIRCUIT
Turn the ignition off.
Disconnect the Throttle Body harness connector.
Ignition on, engine not running.
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 7
4. THROTTLE POSITION SENSOR
With a scan tool, monitor the TP Sensor No.1 voltage with the Sensor harness connector disconnected.
Is the voltage above 4.5 volts?
Yes
- Disconnect the Battery when replacing the Throttle Body Assembly. Replace the Throttle Body Assembly. After installation is complete, using a scan tool select the ETC RELEARN function.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go To 5
5. (K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Disconnect the C2 PCM harness connector.
Measure the resistance between ground and the (K22) TP Sensor No.1 Signal circuit in the Throttle Body harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the short to ground in the (K22) TP Sensor No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go To 6
6. (K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO THE (K922) SENSOR RETURN CIRCUIT
Measure the resistance between the (K22) TP Sensor No.1 Signal circuit and the (K922) Sensor Return circuit in the Throttle Body harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the short between the (K922) Sensor Return circuit and the (K22) TP Sensor No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go To 9
7. (F855) 5-VOLT SUPPLY CIRCUIT OPEN
Turn the ignition off.
Disconnect the C2 PCM harness connector.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnostics.
Measure the resistance of the (F855) 5-volt Supply circuit from the Throttle Body harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes
- Go To 8
No
- Repair the open in the (F855) 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
8. (F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (F855) 5-volt Supply circuit in the Throttle Body harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the short to ground in the (F855) 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Go To 9
9. 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.
Were there any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Replace and program the Powertrain Control Module per Service Information.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
10. THROTTLE FOLLOWER TEST
With a scan tool, perform the Throttle Follower Test.
Monitor the TP Sensor No.1 voltage.
Does voltage start at approximately 0.8 of a volt and go above 3.5 volts with a smooth transition?
Yes
- Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
- Disconnect the Battery when replacing the Throttle Body Assembly. Replace the Throttle Body Assembly. After installation is complete, using a scan tool select ETC RELEARN function.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)