DTC 34

Code 34 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 34 will set if:

^ Engine speed less than 700 RPM.
^ Manifold pressure reading less than 13 kPa.
^ Conditions met for 0.22 second.

OR

^ Engine speed greater than 700 RPM.
^ Throttle angle over 20%.
^ Manifold pressure less than 13 kPa.
^ Conditions met for 0.22 seconds.

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

3. This simulates a high signal voltage to check for 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 circuit 474 can be checked at terminal "C" (should be 5 volts).



DIAGNOSTIC AIDS:

^ An intermittent open in CKTs 432 or 474 will result in a Code 34.

^ CHART C-1D can be used to test the MAP sensor. Also refer toTESTING PROCEDURES/DIAGNOSIS BY SYMPTOM/INTERMITTENTS.