3360368 - Z68 BRAKE LIGHT SWITCH ERROR

The diagnostic equipment signals the following error: C1340 Brake Light Switch
This error can be signalled in two groups of cases. The first is when there is an open circuit at the wiring or at the brake lights switch, the brake lights are burnt out or the reading circuit is damaged. In all these cases the voltage read at the brake lights switch is not in the range below 55% (pedal released) or above 75% (pedal pressed) for the battery voltage.The second group of cases is where there is an open circuit or short circuit (positive or earth) for the wiring or for the brake lights switch, if the switch or the reading circuit is damaged. In all these cases, braking effort is detected without pressure on the brake pedal switch or the closing of the switch contacts.
Results of the tests
1BRAKE PEDAL SWITCH VOLTAGE CHECKAll OKProblems metOperation

Check that the voltage values at the brake pedal switch are correct. In particular:

  • The voltage should be less than 55% of the battery voltage is the pedal is released.
  • The voltage should be more than 75% of the battery voltage is the pedal is pressed See   E2021  BRAKE LIGHTS
Continue to Step 3Voltage at brake pedal switch not correct Continue to Step 2
2ELECTRICAL CHECKSAll OKProblems metOperation
Check that the electrical connections for the brake light circuit are correct Op. 5550D04.Also check that the brake lights are not burnt outContinue to Step 3Wiring faulty Renew the wiring
Brake lights burnt out Replace the burnt out bulb Op.   5540A50 
Third brake light burnt out Replace the third brake light Op.   5550D16 
3BRAKE PEDAL STATE CHECKAll OKProblems metOperation
Connect the diagnostic equipment and, in the PARAMETERS ambient, check the 'BRAKE PEDAL STATUS' parameter. Press the brake pedal and read 'PRESSED'. Release the brake pedal and read 'RELEASED'Continue to Step 5Incorrect reading Continue to Step 4
4CHECK ON BRAKE PEDAL SWITCHAll OKProblems metOperation
Check the condition of the brake pedal switchContinue to Step 5Switch faulty Replace the brake pedal switch Op. 5550D10Continue to Step 3
5BRAKE PEDAL SWITCH ADJUSTMENTAll OKProblems metOperation
Adjust the brake pedal switch so that with the pedal completely pressed it does not complete the last notch, referring to Service News 3350 E 000 AA N°33 03 02 Continue to Step 7.
6BRACKET DISTANCE CHECKAll OKProblems metOperation
Check that the distance between the bracket securing the switch and the reaction bracket for the push rod is correctContinue to Step 7Distance incorrect Replace the pedal unit.Continue to Step 7
7CHECK ON CORRECT OPERATIONAll OKProblems metOperation
Delete the errors using the diagnostic equipment.Carry out road See Test   3340A  ABS intervention check to make the control unit check whether there are still errors present. Return to the workshop and check that the fault is no longer present using the diagnostic equipment.End of diagnosisThe fault persists Continue to Step 6