DTC P0123 Throttle Position (TP)
Sensor Circuit High Voltage
The Throttle Position
(TP) sensor is a potentiometer. The TP sensor is mounted to the left side of
the throttle body. The TP sensor provides a voltage signal that
changes relative to throttle blade angle. This signal voltage is one of
the most important inputs used by the PCM. The TP sensor has a 5.0 volt
reference, a ground and a signal circuit.
The TP sensor signal
voltage should be about 0.6 volt at idle. The TP
sensor voltage should increase to above 4.0 volts at wide open throttle
(WOT).
When
the PCM senses a signal voltage higher than the normal operating range of the
sensor, this DTC sets.
Conditions
for Running The DTC
The ignition switch is
in the ON position or the engine is operating.
Conditions
for Setting The DTC
- The TP sensor signal voltage is
greater than 4.8 volts.
- Condition present for 10.0 seconds.
Action
Taken When the DTC Sets
- The PCM illuminates the Malfunction
Indicator Lamp on the second consecutive ignition cycle that the
diagnostic runs and fails.
- The PCM records the operating
conditions at the time the diagnostic fails. The first time the diagnostic
fails, the PCM stores this information in the Failure Records. If the
diagnostic reports a failure on the second consecutive ignition cycle, the
PCM records the operating conditions at the time of the failure. The PCM
writes the conditions to the Freeze Frame and updates the Failure records.
- The PCM uses a default TP sensor
value.
- The Transmission TCC will not apply.
- High transmission line pressure.
- Fixed transmission shift points,
hard shifts and no fourth gear in hot mode.
Conditions
for Clearing the MIL/DTC
- The PCM turns OFF the malfunction
indicator lamp (MIL) after 3 consecutive ignition cycles that the
diagnostic runs and does not fail.
- A last test failed, or current DTC,
clears when the diagnostic runs and does not fail.
- A history DTC clears after
40 consecutive warm-up cycles, if no failures are reported by this or
any other emission related diagnostic.
- Use a scan tool in order to clear
the MIL and the DTC.
Important
- Remove any debris from the PCM connector surfaces
before servicing the PCM. Inspect the PCM connector gaskets when
diagnosing/replacing the PCM. Ensure that the gaskets are installed
correctly. The gaskets prevent contaminate intrusion into the PCM.
- For any test that requires probing the PCM or component
harness connectors, use the Connector Test Adapter Kit J 35616-A .
Using this kit prevents any damage to the harness connector terminals.
- The following may cause an
intermittent:
- Mis-routed harness
- Rubbed through wire insulation
- Broken wire inside the insulation
- The PCM 5.0 volt reference circuits
are internally connected within the PCM. If all the TP sensor circuits are
OK, inspect the Fuel Tank Pressure Sensor for malfunctions.
- If it is determined that the DTC
occurs intermittently, performing the DTC P1121 diagnostic table may
isolate the cause of the fault.
- For an intermittent, refer to Symptoms
.
The numbers below refer
to the step numbers on the diagnostic table.
- Using Freeze Frame
and/or Failure Records data may aid in locating an intermittent condition.
If you cannot duplicated the DTC, the information included in the Freeze
Frame and/or Failure Records data can help determine how many miles since
the DTC set. The Fail Counter and Pass Counter can also help determine how
many ignition cycles the diagnostic reported a pass and/or a fail. Operate
vehicle within the same freeze frame conditions (RPM, load, vehicle speed,
temperature etc.) that you observed. This will isolate when the DTC
failed. For an intermittent condition, refer to Symptoms
.
- This tests whether
the ground circuit is available to the TP sensor. Test for poor electrical
connections at the TP sensor. Refer to Repairing
Connector Terminals in Wiring Systems.
|
Step |
Action |
Value(s) |
Yes |
No |
|
Did
you perform the Powertrain On-Board Diagnostic
(OBD) System Check? |
-- |
|||
Did
DTC P1639 fail this ignition? |
-- |
|||
Is
the TP sensor voltage or the Throttle Angle above the specified values? |
4.7V, 0% |
|||
Does
the scan tool indicate that this diagnostic failed this ignition? |
-- |
Go to Diagnostic Aids |
||
|
Important After you complete this
diagnosis reconnect the Accelerator and Servo Control Module. Also, clear the
Accelerator and Servo Control Module DTCs that set when the Accelerator and
Servo Control Module was disconnected.
Is
the TP sensor voltage above the specified value? |
4.7V |
Go to A
Diagnostic System Check in Antilock Brake System |
||
Is
the TP sensor voltage below the specified value? |
0.20V |
|||
|
Probe
the sensor ground circuit at the TP sensor harness connector with the test
lamp J 34142-B
connected to B+. Does the test lamp illuminate? |
-- |
|||
|
Measure
the voltage at the 5.0 volt reference circuit to ground using the DMM J 39200 . Is
the voltage greater than the specified value? |
5.0V |
|||
|
Replace
the TP sensor. Refer to TP
Sensor Replacement . Is the action complete? |
-- |
-- |
||
Did
you find and correct the condition? |
-- |
|||
Did
you find and correct the condition? |
-- |
|||
Did
you find and correct the condition? |
-- |
|||
|
Important: Program the replacement
PCM. Refer to PCM
Replacement/Programming . Replace
the PCM. Is the action complete? |
-- |
-- |
||
|
Repair
the 5 volt reference circuit for a short to voltage. Refer to Wiring
Repairs in Wiring Systems. Is the action complete? |
-- |
-- |
||
Does
the scan tool indicate that this test ran and passed? |
-- |
|||
|
Select
the Capture Info option and the Review Info using the scan tool. Does the
scan tool display any DTCs that you have not diagnosed? |
-- |
Go to the applicable
DTC table |
System OK |