Circuit Description
The Powertrain Control Module (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 are out of range by comparing the two values against the high and low limits and engine speed defined within the engine calibration. If the TP or the MAP 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 in which the vehicle is operated. 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
| • | No active MAP DTC"s |
| • | No active ECT DTC's |
| • | No active TP DTC's |
| • | No active Oxygen Sensor DTC's |
| • | No active Fuel Trim DTC's |
| • | No active Injector Control DTC's |
| • | No active Misfire DTC's |
| • | No active KS DTC's |
| • | No active CMP DTC's |
| • | No active EVAP DTC's |
| • | No active VSS DTC's |
| • | No active IAC DTC's |
| • | No active PCM Memory DTC's |
| • | Engine run time is more than 40 seconds. |
| • | Engine speed is between 900 RPM and 6375 RPM. |
| • | Torque Converter Clutch (TCC) is stable to less than 2.5 percent. |
| • | The change in engine speed is less than 50 RPM. |
| • | The change in the IAC valve is less than 5 counts. |
| • | The change in Thottle angle is less than 2 percent. |
| • | The above conditions are present for 1.5 seconds. |
Conditions for Setting the DTC
The predicted MAP sensor is more than or less than a calibrated value for more than 10 seconds.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive key cycles. |
| • | The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tool Freeze Frame/Failure Records. |
Conditions for Clearing the MIL or DTC
| • | The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed. |
| • | A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle. |
| • | Use a scan tool in order 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
The numbers below refer to the step numbers on the Diagnostic Table.
-
A DTC P0507 may also set under Last Test Failed if a vacuum leak is present. Refer to DTC P0507 Idle Speed High.
-
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. A drill bit can be used to clean out any casting flash that may exist in the vacuum port.
-
Replacement PCMs must be reprogrammed and the Crankshaft Position System Variation Learn Procedure must be preformed. Refer to the latest Techline information for programming procedures .
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||
Was a repair necessary? | -- | |||||||||
3 |
Does the MAP sensor voltage change when the engine speed changed? | 2000 RPM | ||||||||
4 |
Does the TP sensor voltage go from below the specified value to above the specified value? | Below 1.0V to above 4.0V | ||||||||
Does the MAP sensor perform correctly through the ranges? | -- | Go to Diagnostic Aids | ||||||||
6 |
Does the scan tool read near the specified value? | 0.0 V | ||||||||
7 |
Does the MAP sensor value on the scan tool change? | 15 in Hg | ||||||||
Was a repair necessary? | -- | |||||||||
9 |
Was a repair necessary? | -- | ||||||||
10 | Replace MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement . Is the action complete? | -- | -- | |||||||
11 |
Does the scan tool read the specified value? | 0.0 V | ||||||||
12 |
Was a repair necessary? | -- | ||||||||
13 | Replace TP sensor. Refer to Throttle Position Sensor Replacement . Is the action complete? | -- | ||||||||
14 |
Was a repair necessary? | -- | ||||||||
Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||||||||
16 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||||||||
17 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |
