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 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.

If the MAP sensor fails the ECM will substitute a fixed 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 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 when:

^ When engine is running.
^ No Code 21.
^ Manifold pressure reading less than 14 kPa.
^ Engine speed is less than 1200 rpm or TPS greater than 15.2%
^ Manifold pressure less than 14 kPa.
^ All conditions met for 0.2 seconds.

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 of an open in CKT 432. if the test light is bright during this test, CKT 432 is probably shorted to ground. If "Scan" reads over 4 volts at this test CKT 432 can be checked by measuring the voltage at terminal "C". (should be 5 volts)


DIAGNOSTIC AIDS:


An intermittent open in circuit 416 or 469 will result in a Code 34.


Refer to TESTING PROCEDURES/DIAGNOSIS BY SYMPTOM/INTERMITTENTS.