Circuit Description
The PCM supplies a 5.0 V reference signal and a ground to both the Throttle Position (TP) sensor and the Manifold Absolute Pressure (MAP) sensor. The TP sensor sends a voltage signal back to the PCM relative to the throttle plate opening and the MAP sensor sends a voltage signal back to the PCM relative to the intake manifold pressure. The PCM can detect if the TP sensor or the MAP sensor is out of range by comparing the two values against the high and low limits against engine speed defined within the engine calibration. If the TP sensor or the MAP sensor are not within the expected limits of the engine calibration, a DTC P0105 is set. During the DTC P0105 test, the actual MAP value is compared to a high limit threshold and low limit threshold for any speed and load that the vehicle is operated in. If the actual MAP value is greater than the high limit, or less than the low limit, a malfunction is indicated.
Conditions for Running the DTC
DTCs P0107, P0108, P0117, P0118, P0122, P0123, P0131, P0132, P0171, P0172, P0201, P0202, P0203, P0204, P0300, P0325, P0341, P0342, P0440, P0442, P0502, P0506, P0507, P1441 not set.
| • | Engine run time is greater than 40 seconds. |
| • | Engine speed is between 600 RPM and 6375 RPM. |
| • | Torque Converter Clutch (TCC) is stable to within 2.5 percent. |
| • | Engine speed is stable to within 50 RPM. |
| • | IAC valve is stable to within 5 counts. |
| • | The TP sensor is stable to within 2 percent |
| • | The above conditions are present for 1.5 seconds. |
Conditions for Setting the DTC
The MAP sensor is out of an expected range defined on the engine calibration. for 14 out of 16 seconds.
Action Taken When the DTC Sets
| • | The Malfunction Indicator Lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the malfunction present. |
| • | The PCM will record the operating conditions at the time that the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers. |
| • | A history DTC stores. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF after three consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
| • | With the ignition turn ON and the engine stopped, the manifold pressure is equal to atmospheric pressure and the signal voltage will be high. This information is used by the PCM as an indication of the vehicle barometric pressure. Comparison of this reading with a known good vehicle with the same sensor is a good way to check the accuracy of a suspect sensor. Readings should be the same +/-0.4 volt. |
| • | The MAP sensor vacuum source should be thoroughly checked for restrictions at the intake manifold. |
| • | A TP sensor that is stuck will attempt an auto zero every time the engine runs. |
| • | If a DTC P0105 cannot be duplicated, the information included in the Freeze Frame/Failure Records data can be useful. Use the scan tool DTC information data in order to determine the status of the DTC. |
- A DTC P0105 may set due to any condition that may cause an unreasonably high or low map value including the following engine conditions:
- A TP sensor that is stuck may attempt to auto zero every time the engine runs. An indication if this happens is the TP percentage will be 0 percent and TP voltage will be high.
- Using a DMM in order to check 5.0 volt reference circuits may not detect small amounts of resistance within the malfunctioning circuit. Connecting a jumper wire from the 5.0 volt reference circuit to the signal circuit detects the small amounts of resistance.
- Certain conditions can produce normal results when probed, but can cause a bad reading when connected. Check for the following conditions on the TP and MAP sensor electrical connectors:
- The MAP sensor needs a dedicated vacuum source. Check the MAP sensor and the MAP sensor vacuum source for the following conditions:
| • | Incorrect cam timing |
| • | Restricted exhaust |
| • | Worn piston rings |
| • | Low fuel pressure |
| • | Spread terminals |
| • | Poor electrical terminal connections |
| • | Vacuum leak |
| • | Split vacuum hose |
| • | Shared vacuum source |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
-
The TP sensor may be able to auto zero itself after several engine starts if it is stuck but may not be able to reach its range near 100 percent. The TP angle should increase steadily. If the voltage value spikes high or low, consider the test failed.
-
The TP sensor has an auto zeroing feature. If the voltage reading is between 0.2 to 0.9 volts, the PCM will assume the TP sensor is at a closed throttle position (0 percent). If the reading is out of the auto zeroing range at closed throttle, look for a binding or damaged linkage.
-
A MAP sensor that displays a BARO value that does not appear normal for the altitude the vehicle is located, the MAP sensor is considered malfunctioning.
-
While starting the engine, the MAP sensor should detect any changes in manifold pressure. This test is to determine if the sensor is stuck at a value.
-
A normal MAP sensor will react as quickly to the throttle changes as they can be made. A MAP sensor should not appear to be lazy or catch up with the throttle movements.
-
The MAP sensor vacuum source should be thoroughly checked for restrictions. This step checks if the reason for no MAP change was due to a malfunctioning sensor or vacuum source problem to the sensor.
-
A short to voltage in the signal circuit would most likely be caused by the 5.0 volt reference circuit. Check for the 5.0 volt reference circuit for being pinched with the signal circuit.
-
Spread terminals or poor electrical connections can produce normal results when probed but cause incorrect readings when connected. Be sure to check all terminals for this condition.
-
A short to voltage in the signal circuit would most likely be caused by the 5.0 volt reference circuit. Check for the 5.0 volt reference circuit for being pinched with the signal circuit.
-
Spread terminals or poor electrical connections can produce normal results when probed but cause incorrect readings when connected. Be sure to check all terminals for this condition.
-
Replacement PCM must be reprogrammed and the Crankshaft Position System Variation Learn procedure must be preformed.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | ||||||||
2 | Are any other DTCs set? | -- | ||||||||
3 |
Did you find and correct the condition? | -- | ||||||||
4 | Does the TP voltage measure below the specified value when the throttle is fully closed? | 0.90 V | ||||||||
Does the TP angle value increase steadily when the accelerator pedal is depressed to greater than the first specified value and decrease steadily returning below the second specified value when the pedal is released? | 98% 1% | |||||||||
Did you find and correct the condition? | -- | |||||||||
Compare the BARO reading with a known good vehicle. The BARO value should be within the specified value of the other vehicle. Does the reading measure within the specified value? | 3 kPa | |||||||||
Start the engine while watching the MAP sensor value with the scan tool. Does the MAP sensor value change while starting the engine? | -- | |||||||||
With the engine running, snap the throttle while watching the MAP sensor display on the scan tool. Does the MAP sensor value change rapidly when the throttle position changes? | -- | |||||||||
Important:: Ensure that the vacuum source is used only for the MAP sensor. Did you find and correct the condition? | -- | |||||||||
11 |
Does the MAP sensor value measure the specified value? | 0.0 V | ||||||||
12 |
Does the 5.0 volt reference value measure the specified value? | 5.0 V | ||||||||
Did you find and correct the condition? | -- | |||||||||
14 |
Does the test lamp illuminate? | -- | ||||||||
15 |
Did you find and correct the condition? | -- | ||||||||
Did you find and correct the condition? | -- | |||||||||
17 | Replace the MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement Did you complete the replacement? | -- | -- | |||||||
18 |
Did you find and correct the condition? | -- | ||||||||
19 |
Does the scan tool read the specified value? | 0.0 V | ||||||||
20 |
Does the scan tool read the specified value? | 5.0 V | ||||||||
Did you find and correct the condition? | -- | |||||||||
Does the test lamp illuminate? | -- | |||||||||
23 |
Did you find and correct the condition? | -- | ||||||||
24 |
Did you find and correct the condition? | -- | ||||||||
25 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement Did you complete the replacement? | -- | -- | |||||||
26 |
Did you find and correct the condition? | -- | ||||||||
|
Important:: The replacement PCM must be programmed and the Crankshaft Position Variation procedure must be performed. Refer to Powertrain Control Module Replacement/Programming and Crankshaft Position System Variation Learn . Replace the PCM. Did you complete the replacement? | -- | -- | ||||||||
28 |
Does the DTC reset? | System OK |
