Non-Turbo

Code 33 Chart:

Code 33 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 ECM CONNECTOR IDENTIFICATION under ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS 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 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 DIAGNOSIS BY SYMPTOM. An open in CKT 452 or the connection will result in 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. Refer to "INTERMITTENTS" in DIAGNOSIS BY SYMPTOM.