Diagnostic Instructions

DTC Descriptors

DTC 033: Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage

DTC 034: Manifold Absolute Pressure (MAP) Sensor Circuit Low Voltage

Circuit/System Description

The manifold absolute pressure (MAP) sensor responds to changes in the manifold vacuum. The electronic control module (ECM) receives this information as a signal voltage that will vary from about 1-1.5 volts at closed throttle, idle, to 4.5-5 volts at wide open throttle.

Conditions for Setting the DTC

DTC 033

DTC 034

Diagnostic Aids

If a shared 5-volt reference circuit is shorted to ground or shorted to a voltage, other 5-volt reference circuits may be affected.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

Scan Tool Reference

Circuit/System Verification

Start the engine, observe the MAP Sensor parameter. The reading should be between 32-42 kPa.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector of the MAP sensor.
2. Ignition ON, verify that the MAP sensor parameter is less than 12 kPa.

⇒	If greater than 12 kPa, test the signal circuit of the MAP sensor for a short to voltage. If the circuit/connections test normal, replace the engine control module (ECM).

Important: The test lamp is used to load the circuit and may not illuminate.

3. Ignition ON, connect a test lamp between the 5-volt reference circuit of the MAP sensor and the negative battery terminal.

Important: The 5-volt reference circuits are internally and externally connected at the ECM. Other component DTCs may be set. If other DTCs are set, review the electrical schematic and diagnose the applicable circuits and components.

4. Test for 4.8-5.2 volts between the 5-volt reference circuit of the MAP sensor and the negative battery terminal.

⇒	If less than 4.8 volts, test the 5-volt reference circuit of the MAP sensor for a short to ground or open/high resistance. If the circuit/connections test normal, replace the ECM.

⇒	If greater than 5.2 volts, test the 5-volt reference circuit of the MAP sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.

5. Ignition ON, test for less than 0.2 volt between the low reference circuit of the MAP sensor and the negative battery terminal.

⇒	If greater than 0.2 volt, test the low reference circuit of the MAP sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.

6. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit of the MAP sensor and the negative terminal of the battery.

⇒	If greater than 5 ohms, test the low reference circuit of the MAP sensor for an open/high resistance. If the circuit/connections test normal, replace the ECM.

7. Ignition ON, install a 3-amp fused jumper wire between the signal circuit and the 5-volt reference circuit of the MAP sensor to verify that the MAP sensor parameter is greater than 102 kPa.

⇒	If less than 102 kPa, test the signal circuit of the MAP sensor for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the ECM.

8. If all circuits/connections test normal, test or replace the MAP sensor.

Component Testing

1. Ignition OFF, disconnect the harness connector of the MAP sensor.
2. Apply 5 volts and ground to the applicable terminals of the MAP sensor and measure the voltage from the signal circuit of the MAP sensor to the negative battery terminal. Apply the specified vacuum to the MAP sensor.

⇒	If voltage is not with in the specified range, replace the MAP sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.