Failsafe Actions and PCM Inputs That Affect Operation
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 Trouble Codes Associated With The Sensor
- Diagnostic Trouble Code 21 Throttle Position Sensor Too High
- Diagnostic Trouble Code 22 Throttle Position Sensor Too Low
- The Failsafe Actions Are:
^ Off Mode Of The TCC
^ No 4th Gear
^ Use Default Valve For TP Sensor
- It Will Recover (Function Normally Again) Upon Valid TP Sensor Operation 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 Trouble Code Associated With The Sensor
- Diagnostic Trouble Code 24 Vehicle Speed Sensor:
^ Detects When The Signal Is Too Low
^ Detects A Large Drop In Frequency
- the Failsafe Actions Are:
^ TCC Will Not Operate
^ The PCM Will Force Immediate 3rd Gear And Will Allow A "Kickdown" Into 2nd Gear When TP Sensor Is Near Wide Open Throttle
- It Will Recover (Function Normally Again) 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 Is Above A Specific Temperature 54°C (130°F)
^ There Are Two Diagnostic Trouble Codes Associated With This Sensor
- Diagnostic Trouble Code 14 Coolant Temperature Sensor High
- Diagnostic Trouble Code 15 Coolant Temperature Sensor Low
- The Failsafe Actions Are:
^ A Default Valve Is Used
^ Allows TCC Operation
- It Will Recover (Function Normally Again) Upon A Valid Sensor Reading
CRUISE CONTROL
^ When Engaged Alters The Shift Pattern To Reduce The Number Of 3-2 And 2-3 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 Injector 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
- Diagnosis Trouble Code 90 TCC Brake Switch Problem
^ Detects When A Change Of State Should Have Occurred And It Did Not
- The Failsafe 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
- Diagnostic Trouble Code 91 PRNDL Switches Problem
^ Detects The 9 False Combinations
^ Checks The P/N Discrete On Starting Or In Fourth Gear
- The Failsafe Actions Are:
^ Use The D4 Shift Schedules
^ TCC 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