DTC 64

Chart - Code 64 MAP Sensor (Signal Voltage Low - High Vacuum):

Wiring Diagram for MAP Sensor:

CODE 64 MANIFOLD ABSOLUTE PRESSURE (MAP) (SIGNAL VOLTAGE LOW)


Circuit Description:
The manifold absolute pressure sensor (MAP) 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 idle (high vacuum) to 4 to 4.5 volts at wide open throttle (low vacuum).


Test Description:Numbers below refer to circled numbers on the diagnostic chart.
1. Code 64 will set if:
Engine rpm less than 600
Manifold pressure reading less than 13 kPa
Conditions met for 1 second
or
Engine rpm greater than 600
Throttle angle over 20%
Manifold pressure less than 13 kPa
Conditions met for 1 second
2. This test to see if the sensor is at fault for the low voltage, or if there is an ECM or wiring problem.


3. This simulates a high signal voltage to check for an open in CKT 432. If the test light is bright during this test, CKT 432 is probably shorted to ground. If "Scan" reads over 4 volts at this test, CKT 416 can be checked by measuring the voltage at terminal "C" (should be 5 volts.)

Diagnostic Aids:

An intermittent open in CKTs 432 or 416 will result in a Code 64. Ignition "ON" engine "OFF," voltages should be within the values shown in the table on the chart. Also CHART C-1D can be used to test MAP sensor. Refer to "Intermittents" in "DIAGNOSIS BY SYMPTOM - NO TROUBLE CODE STORED".