Refer to Engine Controls schematics for wiring views.
Circuit Description
The Manifold Absolute Pressure (MAP) sensor responds to changes in the intake manifold pressure (vacuum). A 5 volt reference is applied to the sensor on the 5 volt reference circuit. A variable resistor moves in relation to the manifold pressure and a voltage signal is sent back to the VCM on the MAP signal circuit. This voltage signal varies from 1.0-1.5 volts at closed throttle to 4.0-4.5 volts at wide open throttle (low vacuum). The VCM utilizes the MAP signal and throttle position in order to determine the correct amount of fuel delivered to the engine.
Conditions for Setting the DTC
The following conditions will set the DTC:
| • | No TP sensor DTCs are set |
| • | Throttle Position is no more than 0.4% when engine speed is no more than 1200 RPM |
| • | Or the Throttle Position is no more than 19.9% when engine speed is greater than 1200 RPM |
| • | MAP is greater than or equal to 4.34 volts |
Action Taken When the DTC Sets
The VCM turns ON the MIL when 1 failure has occurred. The VCM substitutes a calculated value for the MAP sensor value so an acceptable driving condition is maintained.
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
Sensor Accuracy
With the ignition ON and the engine OFF, the manifold pressure is equal to atmospheric pressure with the signal voltage high. The VCM uses this information as an indication of the vehicle's altitude (BARO). Comparison of this reading with a known good vehicle is a good way to check accuracy of a suspect sensor. BARO readings between the known good vehicle and the suspect vehicle should be near the same kPa value.
Intermittent Condition
The intermittent DTC will set when signal voltage goes high for less then one second. A high signal voltage condition of longer than one second duration will set the High Voltage and the Intermittent High Voltage DTCs.
Important: The electrical connector must remain securely fastened.
Important: After removing the MAP sensor from the intake manifold, replace the MAP Sensor to intake manifold seal.
Remove the MAP sensor. Inspect the MAP sensor terminals for intermittent connections.
Refer to Intermittent Conditions for additional diagnostic information.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Important: Be sure to use the same diagnostic equipment for all measurements.
-
This step checks for a short to voltage on the 5V reference circuit.
-
This step checks the integrity of the MAP sensor ground circuit.
-
VCM connector C3 pins 12 and 27 are spliced together inside the VCM. This step isolates the two pins from one another.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing DTCs, use the scan tool in order to record freeze frame and the failure records for reference because the Clear Info function will lose the data. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 |
Does the scan tool display a voltage greater than the second specified value? | 15 in Hg 4.3 V | ||
3 |
Does the scan tool display a voltage less than the specified value? | 1.0 V | ||
4 | The DTC is intermittent. Are any additional DTCs stored? | -- | Go to The Applicable DTC Tables | Go to Diagnostic Aids |
Using the DMM J 39200, probe between the 5V reference circuit at the MAP sensor harness connector and a known good ground. Do not use the sensor ground circuit. Is the voltage greater than the specified value? | 5.2V | |||
Probe the MAP sensor ground circuit at the MAP sensor connector with a test light connected to battery positive. Is the test light illuminated? | -- | |||
7 | Check the MAP sensor vacuum source for a restriction. Was a problem found? | -- | ||
8 | Replace the MAP sensor. Refer to MAP Sensor Replacement. Is the replacement complete? | -- | -- | |
9 | Check for a short to the voltage in the MAP sensor signal circuit. Was a problem found? | -- | ||
Is the voltage greater than the specified value? | 0V | |||
11 |
Is the voltage greater than the specified value? | 0V | ||
12 | Repair the short to ground on the 5V reference circuit. Refer to Wiring Repairs in Engine Electrical. Is the action complete? | -- | -- | |
13 | Using the DMM J 39200, probe between the 5V reference (A) circuit at the VCM connector C3 terminal 12 and a known good ground. Is the voltage greater than the specified value? | 0V | ||
14 | Repair the MAP sensor ground circuit. Refer to Wiring Repairs in Engine Electrical. Is the repair complete? | -- | -- | |
15 | Repair as necessary. Is the action complete? | -- | -- | |
16 | Replace the EGR valve. Refer to EGR Valve Replacement. Is the action complete? | -- | -- | |
17 | Repair the short to voltage on the 5V reference (A) circuit. Refer to Wiring Repairs in Engine Electrical. Is the action complete? | -- | -- | |
18 | Replace the VCM. Important: If the VCM is faulty, reprogram the VCM. Refer to VCM Replacement/Programming . Is the action complete? | -- | -- | |
19 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||
20 | Using the scan tool, select the capture info and the review info. Are any DTCs displayed which were not diagnosed? | -- | Go to The Applicable DTC Table | System OK |
