Throttle Position and Idle Control Parameters
NOTE: These parameters indicate the position of the throttle and the operating condition of various idle speed control devicesDESIRED IDLE RPM
DES IDLE RPM - XXXX RANGE: LOGIC MODULE COMMAND
DES IDLE RPM is the desired idle speed at which the logic module is trying to control the engine. The desired idle rpm is computed internally by the logic module. For a normally operating engine, the actual and desired idle rpm readings should be equal or close to each other.
THROTTLE POSITION SENSOR VOLTAGE
THROTTLE POS (V) - X.X RANGE: 0 TO 5.1 VOLTS
The throttle position sensor (TPS) produces a voltage signal proportional to the throttle position. The signal tells the logic module how wide the throttle is open: low voltage at closed throttle, high voltage at wide-open throttle. The full range of the TPS voltage readings available to the logic module is 0 to approximately 5.1 volts. For most Chrysler engines, THROTTLE POS (V) should range from about 1.0 volt at idle to about 3.5 volts at wide-open throttle. Voltage readings should change smoothly as the throttle moves through its full range.
THROTTLE POSITION SENSOR PERCENTAGE
THROTTLE (%) - XXX RANGE: 0 TO 100%
Some 1991 and later vehicles transmit a throttle position sensor (TPS) signal as a percentage of full-throttle opening, instead of a voltage signal. THROTTLE (%) should range from 0 to 10 percent at idle to above 90 percent at wide-open throttle. Readings should change smoothly as the throttle moves through its full range.
MINIMUM THROTTLE POSITION SENSOR VOLTAGE
MIN TPS (V) - X.X RANGE: 0 TO 5.1 VOLTS
The logic module interprets the lowest voltage received from the TPS as the closed-throttle position. When the throttle closes, the TPS voltage must return to 120 millivolts (10.02 volt on the scanner display) of the revious signal to actuate the AIS motor and control timing. If voltage does not return to the required limits, the engine may idle poorly or stall.
The throttle is opened during starting, the logic module receives a higher than expected minimum TPS voltage. The logic module then sees internal values in its programs to recognize the lower signal as the throttle returns to idle after starting as the MIN TPS(V) value.
AUTOMATIC IDLE SPEED MOTOR IN STEPS
AIS (STEPS) - XXX RANGE: 1 TO 255
On all 1989 and later vehicles except trucks, AIS (STEPS) indicates the position of the automatic idle speed (AIS) motor in stepper motor position counts. A low number indicates that the motor is extended to maintain a low idle speed. A high number indicates that the motor is retracted farther to maintain the required idle speed.
THROTTLE SWITCH
THROTTLE SW - XXXX RANGE: OPEN - CLOSED
The throttle switch discrete parameter on 1989 fuel-injected truck engines should be OPEN when the throttle is off idle. It should be closed (CLAST) when the throttle is closed.