Pinpoint Test D: Flash Code 2 - STOPLAMP Switch Circuit Failure

NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connectors.

D1 CHECK THE STOPLAMP OPERATION
- Apply and release the brake pedal while observing the stoplamps.
- Do the stoplamps operate correctly?
- Yes : GO to D2.
- No : REFER to EXTERIOR LIGHTING SYSTEM article to continue diagnosis of the stoplamps.
D2 CHECK THE STOPLAMP SWITCH CIRCUIT
- Ignition OFF.
- Disconnect: Cruise Control Actuator C122.
- Measure the resistance between the cruise control actuator C122-4, circuit CCB15 (BN/GN), harness side and the cruise control actuator C122-10, circuit GD123 (BK/GY), harness side.
  
  Fig 1: Checking Stoplamp Switch Circuit
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : INSTALL a new cruise control actuator. REFER to CRUISE CONTROL ACTUATOR . REPEAT the self-test.
- No : If equipped with a manual transmission, GO to D3. Otherwise, GO to D5.
D3 CHECK THE STOPLAMP SWITCH SIGNAL CIRCUIT FOR AN OPEN TO THE CPP SWITCH
- Disconnect: CPP Switch C257.
- Measure the resistance between the CPP switch C257-4, circuit CCB15 (BN/GN), harness side and ground.
  
  Fig 2: Measuring Resistance Between CPP Switch C257-4, Circuit CCB15 (BN/GN) And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : GO to D4.
- No : GO to D5.
D4 CHECK THE STOPLAMP SWITCH SIGNAL CIRCUIT FOR AN OPEN
- Measure the resistance between the cruise control actuator C122-4, circuit CCB15 (BN/GN), harness side and the CPP switch (or jumper plug) C257-3, circuit CCB15 (BN/GN), harness side.
  
  Fig 3: Checking Stoplamp Switch Signal Circuit For Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : INSTALL a new CPP switch (or jumper plug). REFER to ENGINE CONTROLS - ELECTRONIC ENGINE CONTROLS article. REPEAT the self-test.
- No : REPAIR the circuit. REPEAT the self-test.
D5 CHECK THE STOPLAMP GROUND CIRCUIT FOR AN OPEN
- Disconnect: Stoplamp Switch C278.
- Measure the resistance between the stoplamp switch C278-5, circuit GD161 (BK/YE), harness side and ground.
  
  Fig 4: Measuring Resistance Between Stoplamp Switch C278-5, Circuit GD161 (BK/YE) And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : GO to D6.
- No : REPAIR the circuit. REPEAT the self-test.
D6 CHECK THE STOPLAMP SWITCH
- Disconnect: Stoplamp Switch C278.
- Install a fused jumper wire between the stoplamp switch C278-4, circuit CCB15 (BN/GN), harness side and the stoplamp switch C278-5, circuit GD161 (BK/YE), harness side.
  
  Fig 5: Checking Stoplamp Switch
  Courtesy of FORD MOTOR CO.
- Measure the resistance between the cruise control actuator C122-4, circuit CCB15 (BN/GN), harness side and the cruise control actuator, circuit GD123 (BK/GY), harness side.
  
  Fig 6: Measuring Resistance Between Cruise Control Actuator C122-4, Circuit CCB15 (BN/GN) And Circuit GD123 (BK/GY)
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : INSTALL a new stoplamp switch. REFER to EXTERIOR LIGHTING SYSTEM article. REPEAT the self-test.
- No : REPAIR the circuit. REPEAT the self-test.