ABS/EDL, and ABS/EDL/ASR (Bosch 5.3)
ABS/EDL, ABS/EDL/ASR (BOSCH 5.3),
The Bosch 5.3 ABS/EDL (with the option of ABS/EDL/ASR for front-wheel drive models) is being introduced on the Audi A6. This system supersedes the Bosch 5.0 ABS.
Front-wheel drive vehicles will be equipped with ABS/EDL/ASR. All-wheel drive vehicles will be equipped with ABS/EDL.
The Bosch 5.3 ABS has a more compact design. The ABS return flow pump -V39-, the ABS hydraulic unit -N55- and the ABS control module (W/EDL) -J104- are combined to form the hydraulic control module.
CAUTION: The bolts which secure the individual components of the hydraulic control module must not be unscrewed.
Safety Precautions And General Information On Troubleshooting
CAUTION: The ABS/EDL and the ASR (traction control system) are safety systems; knowledge of the systems is essential for performing repair work.
Low line version of instrument cluster combination processor (where applicable)
If the 0BD program detects a malfunction in the system, this will be indicated (with ignition on) by the warning lamps in the instrument cluster. There are two different versions of the instrument cluster: "Low line version " and "High line version."
The warning lamps in the "Low line version" are:
^ ABS/EDL warning light -K47- (right-hand arrow)
^ Warning light for brake system -K118- (center arrow, red brake warning symbol)
^ Traction control indicator light -K86- (left-hand arrow).
Further details are given in Warning lamp functions.
High line version of instrument cluster combination processor with driver information display
^ Low line version: red brake warning symbol is illuminated by the warning light for brake system -K118-
^ High line version: red brake warning symbol lights up in the driver information display
^ If the brake system is not fully functional, but the ABS/EDL warning light -K47- and the red brake warning symbol do not light up, this means the malfunction must be sought in the conventional braking system (mechanical/hydraulic components).
Road testing
WARNING:
^ If you drive the vehicle after a malfunction has been detected by OBD, bearing mind that the function of the brake system is restricted, and there is a risk of accident. The brake pressure at the rear wheels is no longer controlled by the electronic brake force distribution function. This can result in excessive braking at the rear and the tail of the vehicle may break out (skid) unexpectedly.
^ When driving or riding in an airbag-equipped vehicle, NEVER hold the scan toot or other test equipment in your hands or lap while in motion. Objects between you and the airbag increase the risk of injury in an accident.
^ During a test drive in an airbag-equipped vehicle, test equipment must always be fastened to and operated from the rear seat by a second technician.
Certain malfunctions will only be detected when the car is moving, so the system can be checked by performing a road test. Maintain a speed above 60 km/h (38 mph) for a period of 30 seconds. After ensuring that it is safe to do so, apply the brakes hard enough to activate ABS-control led braking (this can be felt from the pulsation at the brake pedal).
If a malfunction exists in the vehicle system, carry out the troubleshooting procedure as follows:
- Switch ignition on and observe warning lamps. Table in Warning Lamp Functions will give initial indication of what to look for.
- Observe test condition.
- Connect VAG1551 scan tool and insert "Brake Electronics" address word 03.
- Check control module version and press -4 button.
- Check DTC memory. If a DTC is present in memory, make note of it and then erase DTC memory.
- Conclude transfer of data using "End Output" function 06.
- Repair malfunction according to instructions in DTC table.
- Select "Brake Electronics" once again using address word 03.
- Check and erase DTC memory.
- Conclude data transfer using "End Output" function 06. and disconnect VAG1551 scan tool.
- Make sure all harness connectors are properly connected.
- Perform road test.
Warning lamps should not light up during road test. If they do, the troubleshooting procedure must be repeated.
Note: If the harness connector is not connected to the control module while the vehicle is moving, a sporadic DTC may be stored in the DTC memory of another control module. The mechanical and hydraulic elements of the brake system will still work in the normal way, but the electronic brake force distribution function is not available when the ABS/EDL system is inactive.
WARNING: If you drive the vehicle after a malfunction has been detected by OBD, bear in mind that the function of the brake system is restricted, and there is a risk of accident. The brake pressure at the rear wheels is no longer controlled by the electronic brake force distribution function. This can result in excessive braking at the rear, and the tail of the vehicle may break out (skid) unexpectedly.
General repair information
- Switch ignition off and disconnect battery Ground (GND) strap before removing and installing components.
CAUTION: Before disconnecting the battery, determine the correct coding for the anti-theft radio.
If a component is indicated as being faulty, only replace it if you are sure that the electrical wiring for that component is in proper condition. The wiring must be able to transmit the necessary signals without interference or resistance.
- Check wiring for:
^ Corrosion and loose terminals (intermittent open circuit) in harness connectors and Ground (GND) connections. If any of the connector terminals are bent, broken or corroded, use the VAS1978 wiring repair kit to install new terminals.
^ Open circuits
^ Short circuits to Ground (GND) or to B+
Note: The instructions supplied with the VAS1978 wiring repair kit do not permit repairs to the shielded wiring of the ABS/EDL and related systems.
If the control module has to be replaced, make sure that the correct version is installed, i.e. first check the control module identification. The identification appears on the display of the VAG1551 scan too[ after the data link is established between the VAG1551 and the control module and can also be called up using "Check Control Module Version" function 01.
You can also identify which equipment is installed in the vehicle from a combination of letters on the vehicle data label, which is located in the spare wheel well.
^ 1AC: Anti-lock brake system (ABS)
^ 1AH: Anti-lock brake system with electronic differential lock (ABS/EDL)
^ 1AJ: Anti-lock brake system with electronic differential lock and traction control system (ABS/EDL/ASR)
CAUTION: Absolute cleanliness is required when working on the hydraulic unit.
^ Carefully clean the hydraulic connections and adjacent parts.
^ Do not use aggressive cleaning agents such as brake cleaner, gasoline, thinners or any products which contain mineral oil, such as oils or grease etc.
^ Do not disconnect hydraulic lines until you have cleaned connections.
- Observe appropriate precautions regarding handling of brake fluid.
- Place removed parts on clean surface and cover them. Do not use fluffing cloths or rags.
- Only use genuine packaged parts, and only remove replacement parts from their packaging immediately prior to installation.
- Bleed brake system if connections in system have been opened.
CAUTION:
^ Welding using electrical welding equipment can affect the ABS/EDL or ABS/EDL/ASR system.
^ Make sure the battery negative H cable is disconnected when resistance (spot) welding or electric arc welding anywhere on the vehicle.
Test conditions
^ Vehicle equipped with approved wheels and tire sizes, which must be the same on all four wheels
^ All tire inflation pressures checked according to specification
^ Mechanical and hydraulic parts of brake system in order: no leaks in hydraulic lines and connections (visually inspect hydraulic unit, brake calipers, wheel cylinders, tandem master brake cylinder)
^ Wheel bearings and wheel bearing play OK
^ Wheel speed sensors installed correctly
^ Supply voltage must be OK (not less than 10.0 V)
^ Harness connector on ABS control module (WEDL) -J104- properly connected, with retainer catch engaged
The troubleshooting procedure can only be started with the vehicle stationary and the ignition switched on (or with engine running). The troubleshooting cannot be started if wheel speed exceeds 2.75 km/h 0.70 mph), and will be terminated if the speed exceeds 20 km/h (13 mph).
When testing the ABS/EDL and ASR systems, make sure that the vehicle's electrics are not subjected to electromagnetic interference, i.e. keep the vehicle away from equipment with a high current draw, such as electric welding units.
Technical information required
^ Applicable electrical diagram
^ Installation locations of electrical components
^ Brake mechanical information
^ Brake hydraulic information