Code 63

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR CIRCUIT (SIGNAL VOLTAGE HIGH - LOW VACUUM)
Circuit Description:
The Manifold Absolute Pressure (MAP) sensor responds to changes in manifold pressure (vacuum). The ECM 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 (low vacuum). If the MAP sensor fails, the ECM will substitute a fixed MAP value and use the Throttle Position Sensor (TPS) to control fuel delivery.



Test Description: Numbers below refer to circled numbers on the diagnostic chart.
1. Code 63 will set when:
^ Engine running.
^ Manifold pressure greater than 75.3 kPa (A/C "OFF") 81.2 kPa (A/C "ON").
^ Throttle angle less than 2%.
^ Conditions met for 2 seconds. Engine misfire or a low unstable idle may set Code 63.
2. With the MAP sensor disconnected, the ECM should see a low voltage if the ECM and wiring are OK.
Diagnostic Aids:

With the ignition "ON" and the engine stopped, the manifold pressure is equal to atmospheric pressure and the signal voltage will be high. This information is used by the ECM 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. If idle is rough or unstable, refer to symptoms in Section "B" for items which can cause an unstable idle. An open in CKT 455 or the connection will result in a Code 63.

NOTE: Make sure electrical connector remains securely fastened.

^ Check all connections.
^ 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 output check for further diagnosis.