P0122-THROTTLE POSITION SENSOR 1 CIRCUIT LOW

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 SIGNAL 1 CIRCUIT SHORTED TO GROUND

(K22) TP SIGNAL 1 CIRCUIT SHORTED TO THE (K922) TP 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 DTC

NOTE: 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

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

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

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)

Go To 5

5. (K22) TP SIGNAL 1 CIRCUIT SHORTED TO GROUND

Turn the ignition off.
Disconnect the C2 PCM harness connector.
Measure the resistance between ground and the (K22) TP Signal 1 circuit in the Throttle Body harness connector.

Is the resistance below 100 ohms?

Yes

Repair the short to ground in the (K22) TP Signal 1 circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 6

6. (K22) TP SIGNAL 1 CIRCUIT SHORTED TO THE (K922) TP RETURN CIRCUIT

Measure the resistance between the (K22) TP Signal 1 circuit and the (K922) TP Return circuit in the Throttle Body harness connector.

Is the resistance below 100 ohms?

Yes

Repair the short between the (K922) TP Return circuit and the (K22) TP Signal 1 circuit.

Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

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

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)

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)

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)

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)