Powertrain Controls - ECM/PCM

Code Chart 33:

MAP Sensor Circuit:

CIRCUIT DESCRIPTION:
The manifold absolute pressure sensor (MAP) responds to changes in vacuum (manifold pressure). The ECM receives this information as a voltage that varies from about 1 to 1.5 volts at idle (high vacuum) to 4-4.5 volts at wide open throttle (low vacuum).

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. Code 33 will set if:

^ Engine is running.
^ Manifold pressure is more than 74 kPa with A/C "OFF" or 83.4 kPa with A/C "ON."
^ Throttle angle is less than 1.6%.
^ Conditions are met for 4.8 seconds.
^ Engine misfire or a low unstable idle may set a Code 33.

2. With MAP disconnected the ECM should see a low voltage if the ECM and wiring are good.

DIAGNOSTIC AIDS:
^ An open in CKT 455 or connections will set a code 33.
^ Ignition "ON," engine "OFF," voltages should be within the values shown in the table on the chart. Chart C-1D Manifold Absolute Pressure (MAP) Output Check
^ If idle is Rough unstable or incorrect. - Intermittent Malfunctions