Defect Code 04

Defect Code 04:

Explanation:

No or faulty sensor signal from rear left wheel sensor

Possible causes:

Short or break to ground - or the signal line to/from the speed sensor

Different tyres on rear axle (different wheel circumferences)

Defective pulse wheel (corrosion, dirt, tooth damage)

Incorrect number of teeth on pulse wheel

Air gap (clearance) too large or too small

Wheel speed sensor defective or dirty

Troubleshooting:

Perform following checks and repair or renew defective components as necessary:

- Check tyres of correct tire size on all four wheels

- Check wheel bearing play at all four wheels and renew bearings if necessary

- Check pulse wheel (number of teeth 48, damage, corrosion, dirt build-up)

- Check air gap (clearance) (nominal value 0.05...0.9 mm)

- Check wheel speed sensors (mechanical damage, dirt build-up e.g. metal particles)

- Check plug connections under the left rear seat (firm connection, corrosion, connection interchanged)

- Check plug connections under the left rear seat (firm connection, corrosion, connection interchanged)

Switch off ignition and disconnect the ABS/ASC control unit. Perform following measurements and in the case of deviation renew defective components:

Resistance wire harness side Pin 30/29; nominal value: 650...1600 Ohm; move wires and plug connection (loose contact); if necessary detach plug connection and repeat resistance measurement to locate defect. Perform dynamic speed signal test at Pin 30/29.

Ensure waves are uniform, if necessary, renew pulse wheel or wheel speed sensor.