Notes for towing, or test and repair work, and handling ASR components on vehicles following an accident - RA42001400810X(42-0810)
Towing
When towing at both axles no restrictions are required in respect of ASR vehicles. Only tow with the front axle raised when the ignition is switched off (ignition/starter switch in position 1).
Test and repair work
- The connector from the ASR control unit (N30/1) must be disconnected before driving on to the performance test bench or speedometer tester.
- The system must be depressurized before slackening hydraulic lines on the ASR hydraulic unit (A7/3), and on the pressure accumulator. To do this, switch off the ignition and open the bleed screw "SP" on the ASR hydraulic unit (A7/3) approx. 1 turn and allow the complete contents of the accumulator to flow into the brake fluid receptacle.
- If during repair work, parts on the wheel side such as the brake caliper or brake hose have been replaced without emptying the brake fluid reservoir, the brake system must be bled as previously.
- If the tandem master cylinder or ASR hydraulic unit (A7/3) have been replaced, the system must be bled in accordance with the following sequence (item A-H).
- If the ASR pressurizing pump (M15) or pressure accumulator have been replaced, the system must be bled in accordance with the following sequence (without item C).
Handling ASR components on vehicles following an accident
If, due to the extent of the damage to the vehicle or the position and external appearance of the hydraulic unit after the accident, it can be seen that the hydraulic unit has received a heavy blow, it is to be replaced.
Indications of this are for example:
- Hydraulic lines kinked
- Connections at hydraulic unit leaking
- Electric cables or plug connections damaged
- Metal block of hydraulic unit shows signs of damage
- Hydraulic unit has sprung out of the mounting and cannot just be installed again
If this does not apply, the system must nevertheless be subjected to a thorough function check and the test steps for the solenoid valves and pump must be carried out.
Bleeding ASR hydraulics
- With the ignition switched off, empty pressure accumulator at the bleed screw "SP".
- Connect filling and bleeding equipment.
- Bleed brake system as previously at the wheels. Drain off approx, 0.5 l of brake fluid at each wheel brake.
- Start engine.
- Open bleed screw "SP" until clear bubble- free brake fluid escapes.
- Close bleed screw "SP". Wait for the charging process for the pressure accumulator (return pump/charge pump A7/3m1 runs audibly approx. 30 seconds).
- Switch off engine.
- Connect filling and bleeding equipment and correct fluid level in the brake fluid reservoir.
The ABS test scope is included in the ASR correct fluid level in the brake fluid reservoir.
- The ABS test scope is included in the ASR test program.
- The ground cables from the ASR control unit (N30/1) and from the electronic accelerator pedal control unit (N4/1) are connected to the ground, component compartment (W16/1).
- The following points are to be noted when welding with an electric welder:
Disconnect ground cable at the battery. Connect ground terminal of the welder directly to the part to be welded.
Models 124, 201
- A visual inspection for leaks can be carried out on the connections on the pressure accumulator through the opening in the plastic cover beneath the left front fender.
Model 126
- A visual inspection for leaks can be carried out on the connections on the pressure accumulator through the opening in the plastic cover beneath the left front fender.
Model 129
- A visual inspection for leaks can be carried out on the connections on the pressure accumulator from the underside of the vehicle through the opening in the engine compartment side panel.