DTC 33

Manifold Absolute Pressure (MAP) Sensor Circuit Diagram:

CIRCUIT DESCRIPTION
The PCM applies a 5 volt reference signal, through a resistor in the PCM, to the MAP sensor. The map sensor divides the current from reference signal between a signal return to the PCM, and ground, depending on the manifold pressure. As manifold pressure increases, less current is passed along to ground, and the signal return voltage increases. The PCM monitors the signal voltage and calculates the manifold absolute pressure. The lower the engine vacuum (high absolute pressure), the higher the MAP voltage output, indicating greater demand for fuel. The higher the engine vacuum, the lower the MAP voltage output, indicating less demand for fuel. Under certain conditions (key "ON" engine not running), the MAP sensor is also used to measure barometric pressure.

Code 33 will set when:
^ Engine is running.
^ MAP sensor signal indicates manifold pressure greater than 83.4 kPa with A/C "off" (74 kPa with A/C "ON").
^ TPS indicates throttle opening less than 6%.
^ All conditions exist for 4.8 seconds or more.

NOTE: An engine misfire at idle, or slow unstable idle may cause a code 33 to set.

TEST DESCRIPTION

Code 33 Diagnostic Chart:

Numbers below refer to circled numbers on diagnostic chart.
1. Determines if sensor signal actually indicates conditions necessary for this code to set.
2. Checks PCM and wiring (circuits 432 and 474). A reading of 1 volt or less indicates wiring and PCM are OK.

DIAGNOSTIC AIDS
^ An open in ground circuit 802 will cause a Code 33, and may be accompanied by codes 23 and 66.

^ Also Chart C-1D Manifold Absolute Pressure (MAP) Output Check for additional MAP sensor diagnostic procedures.