Circuit Description
The PCM supplies a 5.0 volt 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 more 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, P0200, P0300, P0301, P0302, P0303, P0304, P0325, P0341, P0342, P0440, P0442, P0502, P0506, P0507 P1441 are not set.
| • | Engine run time is more than 40 seconds. |
| • | Engine speed is between 900 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 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 9 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. |
| • | The MIL/DTCs can be cleared by using the scan tool. |
Diagnostic Aids
| • | With the ignition turned 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 volts. |
| • | 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 and 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 |
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||||
2 | Are any other MAP, TP, A/C or fuel tank pressure sensor DTCs set or last test failed? | -- | Diagnose the other DTCs first | |||||||||
3 |
Was a malfunction found? | -- | ||||||||||
4 | Does the scan tool display a TP voltage below the specified value when the throttle is fully closed? | 0.90 V | ||||||||||
5 |
Does the TP angle value increase steadily when the accelerator pedal is depressed to more than the first specified value and decrease steadily returning below the second specified value when the pedal is released? | 98% 1% | ||||||||||
6 | Check the throttle body for the following conditions:
Was a repair necessary? | -- | ||||||||||
7 | Compare the BARO reading with a known good vehicle. The BARO value should be within the specified value of the other vehicle. Is the BARO reading near the specified value? | 3 kPa | ||||||||||
8 |
Does the MAP reading change by more than the specified value? | 33 kPa | ||||||||||
9 | With the engine still 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? | -- | ||||||||||
10 |
Was a repair necessary? | -- | ||||||||||
11 |
Does the scan tool read the specified value? | 0.0 V | ||||||||||
12 |
Does the scan tool read the specified value? | 5.0 V | ||||||||||
13 |
Was a repair necessary? | -- | ||||||||||
14 |
Does the test lamp illuminate? | -- | ||||||||||
15 |
Is the voltage within the specification? | 5 V | ||||||||||
16 |
Was a repair necessary? | -- | ||||||||||
17 |
Was a repair necessary? | -- | ||||||||||
18 | Replace the MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement . Is the action complete? | -- | -- | |||||||||
19 |
Was a repair necessary? | -- | ||||||||||
20 | Repair the open, high resistance or short to ground in the MAP signal circuit. Is the action complete? | -- | -- | |||||||||
21 |
Does the scan tool read the specified value? | 0.0 V | ||||||||||
22 |
Does the scan tool read the specified value? | 5.0 V | ||||||||||
23 |
Was a repair necessary? | -- | ||||||||||
24 |
Does the test lamp illuminate? | -- | ||||||||||
25 |
Was a repair necessary? | -- | ||||||||||
26 |
Was a repair necessary? | -- | ||||||||||
27 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Is the action complete? | -- | -- | |||||||||
28 |
Was a repair necessary? | -- | ||||||||||
29 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |||||||||
30 |
Does the scan tool indicate that this diagnostic Ran and passed? | -- | ||||||||||
31 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to applicable DTC table | System OK |
