PCM Inputs

THROTTLE POSITION SENSOR
^ Replaces the TV cable and valve
^ Measures the throttle position and inputs it into the PCM.
^ Provides data to develop the shift pattern.
^ There are two diagnostic codes associated with the sensor.
- Code 21 throttle position sensor too high.
- Code 22 throttle position sensor too low.
The Fail-safe actions for codes 21 and 22 are:
^ Off mode of the Torque Converter Clutch (TCC).
^ Inhibit 4th gear.
^ Use default value for TP Sensor in second and third gear, may disable third gear.
It will recover upon a valid range.


VEHICLE SPEED SENSOR
^ Replaces the governor.
^ Measures the speed of the final drive assembly.
^ Provides data to develop the shift pattern.
^ Generates a voltage waveform and its frequency. Determines vehicle speed.
^ There is one diagnostic code associated with the sensor:
- Code 24 vehicle speed sensor.
^ Detects when the signal is too low.
The Fail-safe actions for code 24 are:
^ TCC will not operate for the ignition cycle.
^ The PCM/ECM will force immediate 3rd gear and will allow a kickdown into 2nd gear when TP sensor is near wide open throttle.
It will recover when vehicle speed is above a specific value.


ENGINE COOLANT TEMPERATURE.
^ Measures the engine coolant temperature.
^ The PCM will not command the TCC until the engine coolant temperature is above a specific temperature 54°C (130°F).
^ There are two diagnostics associated with this sensor:
- Code 14 coolant temperature sensor high.
- Code 15 coolant temperature sensor low.
The Fail-safe actions are:
^ A default value is used.
^ Allows TCC operation.
It will recover upon a valid sensor reading.

CRUISE CONTROL
^ When engaged, alters the shift pattern to reduce the number of 3-4 and 4-3 shifts.
A time limit must be met between 3-2 and a 2-3.
A time limit must be met between 4-3 and a 3-4.

ENGINE SPEED
^ Determined by the ignition module.
^ Used to regulate the PWM solenoid duty cycle.

BRAKE SWITCH
^ Controls the TCC solenoid and inputs into the PCM.
^ Disengages the TCC solenoid from the power feed source when the brake is applied.
^ There is one diagnostics associated with this switch. (3800 engine only)
- Code 90 TCC brake switch problem.
^ Detects when a change of state should have occurred and it did not the fail-safe actions are:
^ No cruise control.
It will recover once the switch changes state.

PRNDL SWITCH
^ It is mounted on the manual shaft lever and it gives transmission range based upon lever position.
^ Inputs the selected transmission range into the PCM.
^ Controls shift solenoid state.
^ It is an assembly of four switches that connect to ground.
^ There is one diagnostics associated with this switch.
- Code 91 PRNDL switches problem.
^ Detects the 9 false combinations.
^ Checks the P/N discrete on starting or in fourth gear.
The fail-safe actions are:
^ Use the D4 shift schedules.
^ VCC PWM solenoid will be regulated incorrectly in D3 recovers upon a valid range.
If not properly aligned between D4 and D3 no TCC may occur should set a code if not properly aligned or in wrong range manual LO may not be attainable.