Diagnostic Aids

The ECM supplies a 5 volt signal to pin C (circuit 474) of the Manifold Absolute Pressure (MAP) sensor and supplies a ground path to pin A (circuit 476-Y). The MAP signal from pin B (circuit 432) is a variable voltage which is dependent on the manifold pressure.

Trouble Code 32 indicates that the voltage signal from the MAP sensor is too low. This situation can be observed in engine data display as a "MAP" reading (parameter .0.2) of 14 to 16 kPa. Possible causes of this condition are:

• A. A defective MAP sensor.
• B. Defective wiring, terminals, etc.
• C. An ECM which is unable to properly process signals.

1. If the opposite condition (high MAP signal) is created, then the self-diagnostics can be used to detect this failure by displaying engine data parameter .0.2. With the opposite condition created parameter .0.2 should display a MAP reading of 106 to 108 kPa. To create a high "MAP" signal, disconnect the MAP sensor connector and jumper circuits 432 and 474 together. If the "MAP" reading is now 106 to 108 kPa, the fault must be improper mating of sensor terminals or a faulty MAP sensor.
2. If the "MAP" reading is 105 kPa or less, measure the voltage on circuit 474. If the voltmeter reads 0 volts, then the MAP sensor is not receiving 5 volts and circuit 474 must be repaired for an open or short to ground.
3. If the voltmeter reads 5 volts, then measure the voltage between circuits 474 and 432. If the voltage is 5 volts, check circuit 432 for a short to ground. If the wiring is OK, then the fault must be in the ECM connector or ECM itself.
4. If the voltmeter does not read 5 volts, then an open must exist in either the wiring harness or the ECM. If the "MAP" reading is still 105 kPa or less with circuits 474 and 432 jumpered together at the ECM the fault must be in the ECM connector or ECM itself. If the reading is 106 to 108 kPa, then circuit 432 is open.