Engine Code
SYMPTOM
P0122-THROTTLE POSITION SENSOR 1 CIRCUIT LOW (5.7L)
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. Scan Tool Testing and Procedures
DIAGNOSTIC TEST
1. ACTIVE DTC
Note: If a 5-Volt Supply DTC has also set, diagnose the 5-Volt DTC before continuing. Ignition on, engine not running. With a scan tool, read 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 (NGC) POWERTRAIN VERIFICATION TEST VER-5. Powertrain Verification Test - Ver 5
No>> Go To 5
5. (K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Disconnect the PCM harness connectors.
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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.
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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.
No>> Go To 9
7. (F855) 5-VOLT SUPPLY CIRCUIT OPEN
Turn the ignition off. Disconnect the PCM harness connectors.
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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.
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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.
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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.
No>> Replace and program the Powertrain Control Module per Service Information. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.
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>> Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.
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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.