Fault 13 / Fault Code 34

13: Valve relay Fault code - 34 -

Possible Causes, Elimination, Remarks

Certain faults in the ABS valve area (short-circuit to positive side or earth/ground in a control wire) may also be shown as valve relay faults by the 9288 system tester.

A fault in the ABS valve circuit is normally memorized as an ABS valve fault in the control unit's fault memory.

In the case described above, when the fault memory is read out the display of 2 faults is possible (ABS valve and valve relay).




1. Switch off the ignition. Pull off the control unit plug.

Check the control circuit (wire with relay) - from PIN 20 to PIN 7 - for breaks, short to earth/ground or short to positive side.

If no fault is found, proceed with 2.




If there is a break or a short to the positive side or to earth/ground, pull off the valve relay. Check the wires between terminal 85 on the relay base and PIN 7 on the control unit plug and between terminal 86 and PIN 20.

If the wires are in working order, renew the valve relay.

2. Measure resistance between the following PINs at the control unit plug:
PIN 19 to PIN 17
PIN 22 to PIN 17
PIN 2 to PIN 17
Desired value approx. 1...2 ohm

PIN 21 to PIN 23
PIN 18 to PIN 23
Desired value approx. 2...4 ohm

If the desired value is correct, proceed to Item 3.

If incorrect values are obtained, localize the fault as appropriate.
From PIN 19, 22, 2 to PIN 17 = ABS valves + wiring
From PIN 21 and 18 to PIN 23 = Differential locking valves + wiring

Re ABS valves and wiring



Pull off the 12-pole plug at the hydraulic unit.
Measure the internal resistance of the solenoid valves.
PIN 1 against PIN 4
PIN 3 against PIN 4
PIN 5 against PIN 4
Desired value approx. 0.7...1.7 ohm

Desired value not obtained: renew hydraulic unit.

Re: differential locking valves and wiring:



Pull plug off valve block. Measure internal resistance of solenoid valves.
PIN 1 against PIN 3 and PIN 2 against PIN 4
Desired value 2...4 ohm

If an incorrect value is obtained: renew the valve block.

3. Pull off valve relay (7-pole) at hydraulic unit. Measure at control unit plug PIN 17 in order to determine whether there is a short to the positive side or to earth/ground.

If necessary, interrupt the circuit at the hydraulic unit plug (1 2-pole) and localize the fault by reference to the circuit diagram.

4. Check that the power supply is present at terminal 87 of the relay base (car's electrical system voltage) when the valve relay is pulled off. Desired reading: approx. 12 Volt (car's on-board system voltage).




5. Measure resistance between terminal 87 a on the relay base and the earth/ground wire at the pump motor.

Desired value 2...4 ohm. It is essential for the earth/ground wire and the earth/ground point to be in working order.

If necessary, renew the hydraulic unit (resistor in relay base has increased in value).

6. Check the wires from terminal Li on the relay base to PIN 24 on the control unit plug and from 12 to PIN 35 for a break in circuit.




7. Check that the valve relay is energized (voltage present at solenoid valve).

Reconnect all plugs and the relay.

Push back the protective cap on the locking valve plug block. Switch the ignition off, then switch it on again.

The voltage of the car's electrical system must be present at PIN 1 and PIN 2.

If no voltage is present, renew the valve relay experimentally, or test with the ABS 2-LED tester to make quite sure that the relay is genuinely defective.




If the LED on the ABS tester fails to light up steadily in program switch position 5 with the ignition switched on, the relay is defective.

8. If the valve relay is in working order, renew the PDAS/ABS control unit experimentally (output stage defective).