DTC 33

DTC 33 Chart:

Manifold Absolute Pressure (MAP) Sensor Schematic:

CIRCUIT DESCRIPTION
The Manifold Absolute Pressure (MAP) sensor changes resistance based on manifold vacuum. The Powertrain Control Module (PCM) supplies a 5 volt reference and a ground. The MAP sensor voltage varies from 1.0 to 1.5v at idle (high vacuum) to 4.0 - 4.5v at wide open throttle (low vacuum). The MAP sensor is also used to measure barometric pressure, which allows the PCM to make adjustments for altitude changes.

DIAGNOSTIC TROUBLE CODE (DTC) 33 WILL SET WHEN
^ MAP is greater than 80 kPa (23.6 in. HG).
^ Throttle Position (TP) sensor is less than 12%.
^ Vehicle speed Sensor (VSS) is less than 1 mph.
^ DTC 21 or 22 is not set.
^ Above conditions are met for greater than 5 seconds.

ACTION TAKEN (PCM WILL DEFAULT TO)
The Malfunction Indicator Lamp (MIL) will illuminate. The PCM will substitute a fixed MAP value based on RPM and use the TP sensor to control fuel delivery. 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 455 is open, there may also be a stored DTC 15 or 66.

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. 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 ± 0.4 volt.
^ Disconnect sensor from bracket and twist sensor connector. Output changes greater than 0.1 volt indicates a bad connector or connection.
^ Refer to CHART C-1D, MAP sensor output test to further diagnose system. Chart C-1D Manifold Absolute Pressure (MAP) Output Check
^ If DTC 15 and 33 are both set check for an open in CKT 469.
^ If DTC 33 is intermittent, refer to Diagnosis by Symptom. Testing and Inspection