34 Map Circuit - Voltage Out of Range Low

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Description

The manifold absolute pressure (MAP) sensor is a variable resistor that responds to changes in manifold pressure (vacuum). The PCM measure the voltage drop across the MAP sensor. The voltage ranges from 1.0 to 1.5 volts at idle (high vacuum) to 4.45 volts at wide open throttle (low vacuum).

Code Parameters

Code 34 will set if either:

  • Engine speed is less than 1200 RPM.
  • MAP is 0.2 volts or less.
  • Code 21 and 22 are not present.

OR

  • Engine speed is greater than 1200 RPM.
  • MAP is 0.2 volts or less.
  • TPS is greater than 15.2 present.
  • Code 21 and 22 are not present.

Diagnostic Aids

  • When attempting to diagnose an intermittent problem use the Scan Tool to review supplemental diagnostic information. The supplemental data can be used to duplicate a problem. Select MALF History from Scan Tool EC menu.
  • With the engine Off and key On the map reading should be the same as to barometric because manifold pressure is equal to atmospheric pressure (no vacuum - high voltage). Comparing this reading to a known good vehicle with the same sensor is a good way to check accuracy of a suspect sensor. Readings should be within 0.4 volts.