DTC 33

DTC 33 - MAP Sensor Circuit (Signal Voltage High - Low Vacuum):

MAP Sensor Wiring Circuit:

Circuit Description:
The Manifold Absolute Pressure (MAP) sensor responds to changes in manifold pressure (vacuum). The Powertrain Control Module (PCM) receives this information as a signal voltage that will vary from about 1 to 1.5 volts at closed throttle (idle) to 4.5 4.8 volts at Wide Open Throttle (WOT) (low vacuum).

DTC 33 Will Set When:
^ MAP is greater than approximately 80 kPa.
^ TP sensor is less than 12%.
^ VSS is less than 1 mph.
^ DTC 21 or 22 is not set.
^ Above conditions are met for 10 seconds.

Action Taken (PCM will default to): The Malfunction Indicator Lamp (MIL) will illuminate. The PCM will substitute a fixed MAP value and use the Throttle Position (TP) sensor to control fuel delivery, and the cooling fan will enable.

DTC Chart Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.
1. This step will determine if DTC 33 is the result of a hard failure or an intermittent condition.
2. This step simulates conditions for a DTC 34. If the PCM recognizes the change, the PCM, CKT 416 and CKT 432 are OK. If CKT 469 is open, there may also be a stored DTC 23.

Diagnostic Aids:
With the ignition "ON" and the engine "OFF," the manifold pressure is equal to atmospheric pressure and the signal voltage will be high. This information is used by the PCM as an indication of vehicle altitude. Comparison of this reading with a known good vehicle with the same sensor is a good way to check accuracy of a "suspect" sensor. Readings should be the same +/- .4 volt.

A DTC 33 will result if CKT 469 is open or if CKT 432 is shorted to voltage or to CKT 416.

Disconnect sensor from bracket and twist sensor by hand (only) to check for intermittent connections. Output changes greater than .1 volt indicates a bad connector or connection. If OK, replace sensor.

Refer to CHART C-1D, MAP sensor voltage vs. atmospheric pressure for further diagnosis. Chart C-1D Manifold Absolute Pressure (MAP) Output Check

NOTICE: After repairs use Tech 1 scan tool "Fuel Trim Reset" function to reset long term fuel trim to 128.

If DTC 33 is intermittent, refer to "Diagnosis By Symptom." - Intermittent Malfunctions