Defect Code 04

Defect Code 04:

Explanation:

No or faulty sensor signal from rear left wheel sensor

Possible cause:

Short or break to ground or the signal lines to/from the speed sensor
Different tires 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 tires for 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 buildup)
- 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 wheel speed sensor line (mechanical damage, e.g. pinched points)
- Check plug connections under the left rear seat (firm connection, corrosion, connection interchanged).

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

Resistance wire harness side Pin 44/45; 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 44/45.

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