The Manifold Absolute Pressure (MAP) sensor responds to changes in intake manifold pressure (vacuum). The MAP sensor signal voltage to the PCM varies from below 2.0 volts at idle (high vacuum) to above 4.0 volts with the key on, engine not running, or engine running at wide open throttle (low vacuum).
The MAP sensor is used to determine manifold pressure changes while the linear EGR flow test diagnostic is being run to determine engine vacuum level for other diagnostics and to determine barometric pressure (BARO). The PCM monitors the MAP signals for voltages outside the normal range of the MAP sensor. If the PCM detects a MAP signal voltage that is excessively high, DTC P0108 Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage will be set. If the PCM detects a MAP signal voltage that is excessively low, DTC P0107 Manifold Absolute Pressure (MAP) Sensor Circuit Low Voltage will be set.
The PCM also uses the MAP Sensor for throttle position sensor performance. If the PCM detects a TP in an out of range condition, when the MAP reading is above or below a calibrated amount then DTC P0121 Throttle Position (TP) Sensor Performance will be set.
Check for the following conditions:
• | Monitor the MAP sensor using the scan tool. |
If the MAP sensor does not respond to throttle changes, check the 3X reference circuits from the ignition control module to the PCM. |
If the 3X reference signal is lost the PCM will only update the MAP sensor reading once per key cycle, when the engine is first started. |
Depending on where the MAP sensor voltage (high voltage or low voltage) is when the engine is started, the high or low voltage MAP sensor DTCs will set. |
• | Poor connection at PCM. |
Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Intermittents and Poor Connections Diagnosis and Connector Repairs . |
• | Damaged harness. |
Inspect the wiring harness for damage. If the harness appears to be OK, observe the MAP display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the display will indicate the location of the fault. Refer to Wiring Repairs . |
• | Inspect for kinked and damaged vacuum hoses, ensure that a good vacuum source is available. Refer to Emission Hose Routing Diagram . |
Step | Action | Value(s) | Yes | No | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic System Check performed? | -- | ||||||||||||||
2 |
Did you find a problem? | -- | Go to Diagnostic Aids | |||||||||||||
3 |
Is the MAP value near the specified value? | 0.0 V | ||||||||||||||
4 |
Is the MAP value near the specified value? | 4.95 V | ||||||||||||||
5 |
Is MAP value near the specified value? | 4.95 V | ||||||||||||||
6 |
Did you find a problem? | -- | ||||||||||||||
7 |
Did you find a problem? | -- | ||||||||||||||
8 |
Did you find a problem? | -- | ||||||||||||||
9 |
Did the terminal require replacement? | -- | ||||||||||||||
10 |
Did you find a problem? | -- | ||||||||||||||
11 | Replace the MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement . Is the action complete? | -- | -- | |||||||||||||
12 |
Did you find a problem? | -- | ||||||||||||||
13 |
Important: : Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | -- | |||||||||||||
14 | With the engine idling, monitor the MAP sensor with a scan tool while increasing engine RPM. Does the MAP sensor value change? | -- | System OK |