Pinpoint Test C: The Transmission Control (TC) Switch Is Inoperative

WARNING: This page is about a different variant/trim than selected.

C1 CHECK THE VOLTAGE TO THE TRANSMISSION CONTROL (TC) SWITCH
- Key in OFF position.
- Disconnect: Transmission Control (TC) Switch C279.
- Key in ON position.
- Measure the voltage between TC switch C279-3, circuit 911 (WH/LG), harness side and ground.
  
  Fig 1: Measuring Voltage Between TC Switch C279-3, Circuit 911 Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
1. Yes : GO to C2.
2. No : REPAIR the circuit. TEST the system for normal operation.
C2 CHECK THE TC SWITCH
- Measure the resistance between transmission control (TC) switch C279-3 (component side), and C279-4 (component side), while depressing and releasing the TC switch.
  
  Fig 2: Checking The TC Switch
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms with the TC switch depressed and greater than 10,000 ohms with the TC switch released?
1. Yes : GO to C3.
2. No : INSTALL a new TC switch. Test the system for normal operation.
C3 CHECK CIRCUIT 224 (TN/WH) FOR AN OPEN
- Key in OFF position.
- Disconnect: Powertrain Control Module (PCM) C175.
- Measure the resistance between transmission control switch (TCS) C279-4, circuit 224 (TN/WH), harness side and powertrain control module (PCM) C175-29, circuit 224 (TN/WH), harness side.
  
  Fig 3: Checking Circuit 224 (TN/WH) For An Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
1. Yes : Refer to INTRODUCTION - GASOLINE article.
2. No : REPAIR the circuit. TEST the system for normal operation.