Powertrain Controls - ECM/PCM

Code 33 Chart:

Manifold Absolute Pressure Sensor Wiring Diagram:

CIRCUIT DESCRIPTION:

The manifold absolute pressure (MAP) sensor responds to changes in manifold pressure (vacuum). The ECM receives this information as a signal voltage that will vary from about 1 to 1.5 volts at idle to 4-4.5 volts at wide open throttle (Low vacuum).


NOTE: Because of all the possible color code combinations used on electrical wiring diagrams, always refer to SCHEMATIC DIAGRAMS/ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS/ECM CONNECTOR IDENTIFICATION for correct color code identification of circuit.

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

1. Code 33 will set when:

- Engine Running.
- Manifold pressure greater than 74 kPa (A/C "OFF") 83.4 kPa (A/C "ON").
- Throttle angle less than 2%.
- Conditions met for 5 seconds.
and
- Vehicle in first gear.
or
- Vehicle not in first gear and TPS is less than or equal to 6%.
- Engine misfire or a low unstable idle may set a Code 33.

2. With the MAP sensor disconnect the ECM; should see a low voltage if the ECM and wiring is OK.


DIAGNOSTIC AIDS:



An open in circuit 470 or the connection will result in a Code 33. Ignition "ON" engine "OFF" voltages should be within the specifications Refer to SPECIFICATIONS/ELECTRICAL AND ELECTRONIC SPECIFICATIONS. Also, CHART C-1D can be used to test the MAP sensor.

Refer to TESTING PROCEDURES/DIAGNOSIS BY SYMPTOM/INTERMITTENTS.