Audi Workshop Service and Repair Manuals

Special tools and workshop equipment required

• ◆ V.A.G 1526 A
• ◆ V.A.G 1527 B
• ◆ V.A.G 1594 A
• ◆ V.A.G 1598/31
• ◆ VAS 5051 with VAS 5051/1

Note:

Command from accelerator pedal sender (potentiometer) to engine control unit for opening throttle valve is suppressed for safety reasons when brake is pressed. For this purpose, the control unit requires signals from both the brake light switch and the brake pedal switch.

If the brakes are actuated when the accelerator pedal is held at a constant position, the engine speed is immediately reduced to idling speed. Incorrectly adjusted switches may lead to unwanted regulating actions.

Test sequence

• ‒ Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 -Engine electronics" in the selection. For this purpose, the ignition must be switched on.

→ Display on VAS 5051:

• ‒ Under -1- select the diagnostic function "08 - Read measured value block".

→ Display on VAS 5051:

•     1 -    Enter display group
  max. input value = 255

• ‒ Enter "066" for "display group number 066" in zone -2- and confirm the entry by pressing the Q key.

→ Display on VAS 5051:

• ‒ Check brake light/brake pedal switch in display zone -2-.

• ‒ Exit the function "08 - Read measured value block" by pressing the ◂key.

If the display is not as described:

Check switch

• ‒ Remove driver's storage compartment.

=> General Body Assembly, Interior; Repair group 68; Storage compartments, covers; Removing driver's storage compartment

• ‒ Unplug connector from brake light/brake pedal switch.

• ‒ → Connect multimeter between contacts 1 and 4 to measure resistance.
• ‒ Specified value: ∞ω (no continuity)
• ‒ Press brake pedal.
• ‒ Specified value: approx. 0 ω
• ‒ Connect multimeter between contacts 2 and 3 to measure resistance.
• ‒ Specified value: approx. 0 ω
• ‒ Press brake pedal.
• ‒ Specified value: ∞ω (no continuity)

If the specified values are not obtained:

• ‒ Replace brake light/brake pedal switch.

If specifications are attained:

• ‒ Check the power supply.

Checking power supply

• ‒ → Connect voltage tester V.A.G 1527 B as follows:

• ‒ The LED should illuminate.

• ‒ Switch the ignition on.
• ‒ The LED should illuminate.

If the LED does not illuminate:

• ‒ Check the wiring between contact 1 and 2 of connector for open circuit/short to earth:

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

• ‒ Rectify any open/short circuit as necessary.

If the LED illuminates:

• ‒ Check actuation.

Checking actuation

• ‒ Connect test box V.A.G 1598/31 to wiring harness for engine control unit; do not connect the engine control unit => Page 24-19.

• ‒ → Check for open circuit and short to positive or earth in the following wiring connections:

• ‒ Rectify any open/short circuit as necessary.