Skoda Workshop Service and Repair Manuals

Test brake light switch -F- and brake pedal switch -F47- As the injection system operates with an accelerator pedal position sender (potentiometer), which may become defective, for reasons of safety the engine is cut-off when the brake is activated. To do so the brake light switch signal and additionally the brake pedal swicth signal in the diesel direct injection system control unit -J248- is required. If the brake pedal is activated with the accelerator pedal constantly pressed, the engine immediately slows down to idling speed. A defective brake pedal switch may result in involuntary cut-off procedures. Special tools and workshop equipment required t  Vehicle system tester -V.A.G 1552- t  Diagnostic cable -V.A.G 1551/3- t  Hand multimeter (e.g. -V.A.G 1526 A-) t  Adapter cable set (e.g. -V.A.G 1594 A-) t  Test box -V.A.G 1598/31- Test condition

l  Fuses No. 2 and No. 28 O.K. Check for proper operation –  Connect vehicle system tester - V.A.G 1552-. Switch on the ignition and select the engine control unit with “Address word” 01 → Chapter. –  Select function 08 “read measured value block” and display group number 006.

Readout on display: –  Observe readout in display field 2.    Specified value:    X00 (if brake pedal not pressed)    X11 (if brake pedal pressed) –  Select function 06 “End output” and confirm entry with Q. –  Switch off the ignition. –  If the display does not occur as described: Testing switch –  Remove the bottom part of the dash panel on the driver's side → Body Work; Rep. Gr.70. –  Remove the left footwell blower. –  Unplug the connector from the brake light/brake pedal switch.

Reading measured value block 6 -> 0 km/h 000 000000 0

–  Connect the handheld multimeter for voltage measurement between contact 1 and 4.    Specified value: ∞ Ω (no continuity) –  Operate brake pedal.    Specified value: max. 1.5 Ω

–  Connect the handheld multimeter for voltage measurement between contact 2 and 3.    Specified value: max. 1.5 Ω –  Operate brake pedal.    Specified value: ∞ Ω (no continuity) If the specified values are not reached: –  Replace the brake light/brake pedal switch. If the specified values are reached: Checking voltage supply

–  Connect the handheld multimeter for voltage measurement as follows:

Plug connection contact	Specification
1 + earth	approx. battery voltage

–  Switch on the ignition.

Plug connection contact	Specification
2 + earth	approx. battery voltage

If the specified values are not reached: –  Check the cable between contact 1 of the plug and fuse 2 according to the current flow diagram for interruption → Current flow diagrams, Electrical fault finding and Fitting locations. –  Check the cable between contact 2 of the plug and fuse 28 according to the current flow diagram for interruption → Current flow diagrams, Electrical fault finding and Fitting locations. If the specified values are reached: Checking wires –  Switch off the ignition. –  Connect the test box -V.A.G 1598/31 - to the wiring loom on the engine control unit → Chapter.

–  Check the following wires for interruption or short-circuit to earth or positive:

Plug connection contact	Test box -V.A.G 1598/31- bush
3	65
4	32

–  If necessary eliminate wire interruption or short-circuit.