With Speed Density Update

Manifold Absolute Pressure (MAP) Signal Voltage Low:

Manifold Absolute Pressure (MAP) Sensor Circuit:

CIRCUIT DESCRIPTION
The Manifold Absolute Pressure (MAP) sensor responds to changes in manifold pressure (vacuum). The Electronic Control Module (ECM) receives this information as a signal voltage that will vary from about 1 - 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 34 will set if:
^ Engine RPM less than 700
^ Manifold pressure reading less than 13 kPa
^ Conditions met for 1 second
Or
^ Engine RPM greater than 700
^ Throttle angle over 20%
^ Manifold pressure less than 13 kPa
^ Conditions met for 1 second
2. This test to see if the sensor is at fault for the low voltage, or if there is an ECM or wiring problem.
3. This simulates a high signal voltage to check for an open in circuit 432. If the test light is bright during this test, circuit 432 is probably shorted to ground. If "SCAN" reads over 4 volts at this test, circuit 416 can be checked by measuring the voltage at terminal "C" (should be 5 volts.)

DIAGNOSTIC AIDS
An intermittent open in circuits 432 or 416 will result in a Code 34.
Ignition "ON" engine "OFF," voltages should be within the values shown in the table on the chart. Chart C-1D can also be used to test MAP sensor.
Refer to Diagnostic Charts / Chart C-1D. Chart C-1D Manifold Absolute Pressure (MAP) Output Check
Refer to Diagnosis by Symptom / Intermittents. - Intermittent Malfunctions