DTC 34

Code 34 Chart:

Code 34 Wiring Diagram:

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).


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 34 will set if:

^ Engine speed is less than 600 rpm.
^ Manifold pressure less than 13 kPa
^ Conditions met for 1 second
OR
^ Engine speed is greater than 600 rpm.
^ Manifold pressure less than 13 kPa
^ Throttle angle greater than 20%
^ Conditions met for 1 second

2. This tests to see if the sensor is at fault for the low voltage, or if there is a ECM or wiring problem.

3. This simulates a high signal voltage to check for an open in CKT 432. If the test lite is bright, CKT 432 is shorted to ground. If scan reads 4 + volts, CKT 474 can be checked @ terminal "C", it should be 5 volts.

DIAGNOSTIC AIDS:


An intermittent open in circuits 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.

Refer to TESTING PROCEDURES/DIAGNOSIS BY SYMPTOM/INTERMITTENTS.