DTC 33

Code 33 Chart:

MAP 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 (high vacuum) to 4 to 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 if:

^ No Code 21 or 22.
^ Engine is running.
^ Manifold pressure greater than 74 kPa (A/C "OFF") 83.4 kPa (A/C "ON").
^ Throttle angle less than 2%.
^ The above conditions are met for 4.8 seconds.
^ Engine misfire or a low unstable idle may set code 33.

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


DIAGNOSTIC AIDS:

If idle is rough or unstable, Refer to Powertrain Management/Computers and Control Systems/Testing and Inspection/Procedures/Diagnosis by Symptom. An open in CKT 802 or the connection will result in a Code 33. CHART C-1D can also be used to test the MAP sensor.