With Speed Density Update

MAP Sensor Diagnosis Chart:

Wiring Diagram for Manifold Absolute Pressure (MAP):

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 to 1.5 volt 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 when:
- When engine rpm less than 700
- Manifold pressure less than 13 kPa
-
Or
- When engine rpm greater than 700
- Throttle angle greater than 20%
- Manifold pressure less 13 kPa
- Conditions met for 1 second
2. With the MAP sensor disconnected, the ECM should see a low voltage if the ECM and wiring is OK.
3. This simulates a high signal voltage to check for an open in CKT 432. If lite is bright, CKT 432 is shorted to ground. If scan reads 4+ volts, CKT 474 can be checked at terminal "C," it should be 5 volts.

DIAGNOSTIC AIDS:
If idle is rough or unstable See "DIAGNOSIS BY SYMPTOMS," for items which can cause an unstable idle. Testing and Inspection
An intermittent open in CKTs 432 or 474 will result in a Code 34. Ignition "ON" engine "OFF," voltages should be within the values shown in the table on the chart. Also chart C-1D can be used to test the MAP sensor. Chart C-1D Manifold Absolute Pressure (MAP) Output Check