Pressure Switch/Power Steering -F88-, Testing

Pressure Switch/Power Steering -F88-, Testing

The function of the pressure switch/power steering is to stabilize the idling speed when the steering wheel is on full lock (left or right).

Test sequence
- Connect the vehicle diagnostic, testing and information system VAS 5051, Vehicle Diagnostic, Testing and Information System VAS 5051, Connecting and Selecting Functions and select the vehicle system "01 - Engine electronics" from the menu. When doing this the engine should be idling.







Display on VAS 5051:
- Select the diagnosis function "08 - Read data block" from the menu -1-.







Display on VAS 5051:
1 - Enter display group
(figures up to 255)
- Using the keypad -2-, enter "056" to select Display group 056 and confirm entry with Q button.







Display on VAS 5051:
- Check readout for pressure switch/power steering (display zone -4-).







If the display values do not appear as described:

Testing switch
- Unplug connector from pressure switch/power steering -F88 on power steering pump.







- Connect multimeter to switch (resistance measurement range).
- Start the engine.
- Specification: Infinity Ohms (no continuity)
- Turn steering wheel to full lock (left and right).
- Specification: approx. 0 Ohm

If the display does not change:
- Replace pressure switch/power steering -F88-.

If the display changes:
- Test the wiring.

Testing wiring
- Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the engine control module itself. Scan Tool Testing and Procedures







- Test for open circuit and short to positive or Ground in the following wiring connections:

Connector Contact Test box VAG 1598/3 Socket
1 49
2 50

- Correct short circuit or open circuit if necessary.