DTC 33

Code 33 Chart:

Wiring Diagram:

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 4.5-4.8 volts at wide open throttle (low vacuum).
If the MAP sensor fails, the ECM will substitute a fixed MAP value and use the Throttle Position Sensor (TPS) to control fuel delivery.

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 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 2%.
^ 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. Also CHART C-1D can be used to test the MAP sensor.

^ If idle is Rough unstable or incorrect. Refer to TESTING PROCEDURES/DIAGNOSIS BY SYMPTOM/INTERMITTENTS.