P0123-THROTTLE POSITION SENSOR 1 CIRCUIT HIGH (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 No.1 voltage is greater than 4.8 volts for 25 ms. One Trip Fault. ETC light will illuminate.

Possible Causes

(K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE

(K22) TP SENSOR NO.1 SIGNAL CIRCUIT OPEN

(K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO THE (F855) 5-VOLT SUPPLY CIRCUIT

(K922) SENSOR RETURN CIRCUIT OPEN

THROTTLE POSITION SENSOR/THROTTLE BODY

THROTTLE PLATE JAMMED AGAINST THE MAXIMUM STOP

PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Diagnostic Test

1.TP SENSOR NO.1 VOLTAGE ABOVE 4.8 VOLTS

NOTE: When this DTC is Active the engine speed, torque, and vehicle speed are limited to a Limp in mode.

NOTE: Make sure the throttle is fully closed and free from binding or carbon build up.

NOTE: If a 5-Volt Supply DTC has also set, diagnose the 5-Volt DTC before continuing.

NOTE: If P2101 is also set, then make sure that the blade moves freely and does not hang up near Wide Open Throttle before trying to repair P0123.

Is the voltage above 4.8 volts?

Yes

Go To 2

Go To 8

2.THROTTLE POSITION SENSOR

Is the voltage below 0.5 of a volt with the jumper wire installed?

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 3
NOTE: Remove the jumper wire before continuing.

3.(K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE

Is the voltage above 0 volts?

Yes

Repair the short to battery voltage in the (K22) TP Sensor No.1 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 4

4.(K22) TP SENSOR NO.1 SIGNAL CIRCUIT OPEN

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 diagnosis.

Is the resistance below 5.0 ohms?

Yes

Go To 5

Repair the open in the (K22) TP Sensor No.1 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

5.(K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO THE (F855) 5-VOLT SUPPLY CIRCUIT

Is the resistance below 100 ohms?

Yes

Repair the short between the (F855) 5-volt Supply circuit and the (K22) TP Sensor No.1 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 6

6.(K922) SENSOR RETURN CIRCUIT OPEN

Is the resistance below 5.0 ohms?

Yes

Go To 7

Repair the open in the (K922) Sensor Return circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

7.PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

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)

8.THROTTLE FOLLOWER TEST

Does voltage start at approximately 0.3 of a volt and go above 4.7 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 the ETC RELEARN function.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)