Skylark V6-3100 3.1L VIN M SFI (1996)
Powertrain Control Module: Description and Operation
PCM Inputs
ENGINE COOLANT TEMPERATURE (ECT) SENSOR
MASS AIR FLOW (MAF) SENSOR
INTAKE AIR TEMPERATURE (IAT) SENSOR
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
FUEL CONTROL HEATED OXYGEN SENSOR (HO2S 1)
CATALYST MONITOR HO2S 2 SENSOR
THROTTLE POSITION (TP) SENSOR
EGR PINTLE POSITION SENSOR
KNOCK SENSOR (KS)
AC REQUEST SIGNAL
This signal indicates to the PCM that an AC mode is selected at the AC control head. The PCM uses this information to adjust the idle speed
before turning "ON" the A/C clutch. If this signal is not available to the PCM, the A/C compressor will be inoperative.
AC REFRIGERANT PRESSURE SENSOR
The AC refrigerant pressure sensor signal indicates high side refrigerant pressure to the PCM. The PCM uses this information to adjust the idle air
control valve to compensate for the higher engine loads present with high AC refrigerant pressures and to control the cooling fans. A fault in the
AC refrigerant pressure sensor signal will cause DTC P053O to set.
TCC BRAKE SWITCH
The TCC brake switch signal to the PCM indicates when the brake pedal is applied. The TCC brake switch information is used by the PCM mainly
to control the Transaxle torque converter clutch.
TRANSAXLE RANGE SWITCH
The Transaxle Range Switch is part of the Transaxle Park / Neutral Position (PNP) switch mounted on the transaxle manual shafi. The 4 inputs
from the transaxle range switch indicate to the PCM which position is selected by the Transaxie selector lever. This information is used for
transmission shift control, ignition timing, EVAP canister purge, EGR and IAC valve operation.
The combination of the four transaxie range input states determine the PCM commanded shift pattern. The input voltage level at the PCM is high
(B+) when the transaxle range switch is open and low when the switch is closed to ground. The state of each input is represented on the scan tool
as X=high voltage level, 0=10w voltage level. The four parameters represent trasaxle range switch Parity, A, B, and C inputs respectively
TRANSAXLE FLUID TEMPERATURE (TFT) SENSOR
The Transaxie fluid temperature sensor is a thermistor which changes value based on the temperature of the Transaxle fluid. A high Transaxle
fluid temperature may cause the vehicle to operate in Hot Mode. While in Hot Mode, shift points may be altered, 4th gear disabled, and TOO
forced ON in 2nd gear. A failure in the TFT sensor or associated wiring should cause DTC P0712 or P0713 to set. In this case, engine coolant
temperature will be substituted for the TFT sensor value, and the Transaxle will operate normally.
VEHICLE SPEED SENSOR (VSS)
7X CRANKSHAFT POSITON SENSOR
24X CRANKSHAFT POSITION (CKP) SENSOR
3X REFERENCE LOW
The PCM uses this signal, from the ignition control module to calculate engine speed and crankshaft position over 1280 RPM. The PCM also uses
the pulses on this circuit to initiate injector pulses. If the PCM recieves no pulses on this circuit, DTC P1374 will set and the PCM will use the
24X reference signal circuit for fuel and ignition control.
This is a ground circuit for the digital RPM counter inside the PCM, but the wire is connected to engine ground only through the ignition control
module. Although this circuit is electrically connected to the PCM, it is not connected to ground at the PCM. The PCM compares voltage pulses
on the reference input circuits to pulses on this circuit, ignoring pulses that appear on both.
