Test 15/Fault Code 31

Test point 15
ABS valve Inlet FL Open circuit / short to ground / short to positive Fault code 31

Use System Tester 9288 to check operation of the ABS solenoid valves in the Drive links menu.

1. With the ignition switched off, disengage connector from hydraulic unit (pull slide upwards). Check resistance between pin 7 and pin 15 on hydraulic unit. Specification: approx. 9 - 10 Ohm. Specification not o.k.: Replace hydraulic unit. Caution: The resistance specifications on the hydraulic unit differ according to the solenoids.All inlet solenoids and the ABD solenoids (USV +ASV) 9 - 10 Ohm. All outlet (exhaust) solenoids 4 - 5 Ohm.

2. Switch off ignition and pull off connector from control unit. Check PIN 5 of control unit connector to PIN 7 of hydraulic unit connector for continuity (open circuit) and for short to ground or short to positive.

3. If the above items (1...2) are o.k., replace control unit on a trial basis (final stage faulty). Then check operation of front left solenoid valves (MV) with System Tester 9288 on Drive links menu (reaction of left front wheel). If reaction is not o.k., check hydraulic or electrical assignment (see below text). Assignment check: In Drive links menu, front left solenoid valves (MV) sub-menu, the left front wheel must lock in test step 2. Diagnostic/Test Plan For Actuators (Drive Link) If a different wheel locks, the assignment is incorrect.

4. If the drive links check described under item 3 above is not o.k but if no hydraulic pipes or electrical wires have been interchanged and if the control unit was replaced, the hydraulic unit must be replaced (mechanical fault in ABS solenoid valve).

Note: Reuse the old control unit again afterwards