Electrical - ABS Light ON, Wire Harness Damage
97 ABS warning light on - wire harness damage
97 13 35
2033412/1
March 27, 2013
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Vehicle Information
Condition
The customer may complain of one of the following conditions:
^ Steering wheel lock does not work.
^ Various warning lights are on.
^ Steering feels stiffer than usual.
^ The engine cannot be switched off.
^ The ignition key cannot be removed.
There are DTC entries present in the system (static or sporadic):
DTC with description "Brake control unit, no signal/communication" is present in several control units.
^ DTC 01316 - Brake Control Module - No signal/communication
^ DTC U012200 - ESP no communication
^ DTC U012100 - ABS Control Module no communication
DTC entry in ABS Control unit, J104 (03). One or more may be present:
^ DTC 00290 (008 - ABS Wheel Speed Sensor, LR-G46, Incorrect signal)
^ DTC 00290 (012 - ABS Wheel Speed Sensor, LR-G46, Electrical fault in circuit)
^ DTC 0283 (008 - Left Front ABS Wheel Speed Sensor-G47, Incorrect signal)
^ DTC 0283 (012 - Left Front ABS Wheel Speed Sensor-G47, Electrical fault in circuit)
This condition does not result in any drivability concerns. The steering system is fully connected.
Technical Background
The insulation for the ABS wheel speed sensor is damaged in production. Over time, this can lead to corrosion on the wires and restricted functions
with the ABS control module. Only the wires in the left bulkhead grommet (Figure 1) are affected.
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Production Solution
Improved installation procedure at the factory.
Service
There are two different types of service actions based on the two types of DTC entries that can be found in the system.
For vehicles with the DTC description "Brake Control Module - No signal/communication" present in several control units, proceed as follows:
1. Perform a voltage drop measurement on terminal 30 - supply for ABS control unit - under load (as described below). For the pin assignment, see
ElsaWeb wiring diagram.
Proposed voltage drop measurement (using an A4 as an example):
^ Verify the fuse is good.
^ Apply a load (1.7 A = 21 W) on pin 7 (T38a) to ground
^ Set the digital multi-meter to DC Volts (Direct current voltage)
^ Connect the black multi-meter measuring tip to pin 7 (T38a) and connect the red measuring tip to fuse SC6 while keeping the fuse in the
socket.
^ If the voltage drops (over 0.3V), the wiring loom around the grommet must be checked (Figure 2)
Tip:
For better access to all sections of the wiring loom, the wheel arch liner and the windscreen washing reservoir must be removed.
2. If damage is found, please contact the Technical Assistance Center (TAC) and take a photo of the damage:
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^ Measure the distance from the grommet front side (Figure 3, point 1) to the point of damage point (Figure 3, point 2). Include this measured
distance in the TACS contact.
^ Take a photo, using camera flash, of the grommet and original harness position from the passenger compartment (Figure 4). Please attach the
photo to the TACS contact.
3. Repair the damaged cable in the wiring loom using the VAS1978B wiring harness repair kit.
4. Remove the sections of the individual cable where the copper wires are black or corroded.
5. Pull back the insulation for the complete wiring loom, for a distance of about 40 cm from the grommet towards the front of the vehicle, and
inspect for additional damage or corrosion.
For vehicles with the DTC description, "ABS Wheel Speed Sensor - Incorrect signal or Electrical fault in circuit", present in multiple control units,
proceed as follows.
1. Perform the same measurements as above using the correct pin/fuse location listed in ElsaWeb for the affected ABS wheel speed sensor.
2. Take a photo of the grommet position from the inside of the vehicle and attach it to the TACS contact.
3. Repair any damage found and ensure the black or corroded wires are removed.
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Warranty
Required Parts and Tools
Additional Information
All parts and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Department and service
manuals for the latest information.
