DTC 34

Fig. 040 Code 34 MAP Sensor Circuit:

FIg. 068 - Wiring Diagram for Code 34 MAP Sensor. VIN Z:

CODE 34

MAP SENSOR

SIGNAL VOLTAGE LOW

5.0L "F" SERIES

4.3L "B/G" SERIES

FUEL INJECTION (TBI)



CIRCUIT DESCRIPTION
The Manifold Absolute Pressure Sensor (MAP) 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 MAP value and use the Throttle Position Sensor (TPS) to control fuel delivery.
Code 34 will set when signal is too low and ignition is on.

TEST DESCRIPTION
1. Confirms Code 34 if that fault is still present.
2. If the ECM recognizes and sets Code 33, high MAP signal, the ECM and wiring are OK.

DIAGNOSTIC AIDS
An intermittent open in CKT 432 or 416 will result in a code 34.
With ignition on and engine off, the voltage on CKT 432 should be within the values given on the table in the flow chart.
Chart C-1D can also be used to diagnose the MAP sensor.
Also see DIAGNOSIS BY SYMPTOMS; INTERMITTENTS