Anti-lock brake system (ABS) - General repair instructions

Anti-locking System (ABS)  

General Notes Before Repair  

When the ignition is switched on, the "ABS" symbol in the instrument housing illuminates and extinguishes after approx. 4 sec. If the ABS telltale does not go out or if it comes on sporadically or stays on permanently during driving, there is a fault in the system.

Diagnosis of fault:   With diagnosis switch KM-640 swith position "K" or with TECH 1/TECH 1A in connection with Programme-Module "Opel/Vauxhall 87-94 ECU" or TECH 2. Following driving there follows further selftesting of the ABS, which can be made noticable through the noise of the return pump and indicated with the ABS control light.   When braking hard, the vehicle remains free from wheel lock until it almost stops (approx. 4 km/h/2.5 mph), thus guaranteeing manoeuvrability.

  Important!   

The following points must be observed when working on vehicles with ABS:  

-  When carrying out electrical welding, the plug must be removed from the electronic control unit.  

-  During painting work the ABS-Control unit may for a short time be subjected to 95 ° C and for a longer period - ca. 2 Hours - with a max. of 85 ° C.  

-  After working on the brake system, it must be bled and a pressure inspection carried out.  

-  All connections are to be checked for leaks.  

-  Observe proper seating of battery connections.  

-  When starting the engine, do not use a quick-charger.  

-  Observe proper seating of all wiring harness connections.  

-  Never unplug the wiring harness multiplug from the electronic control unit or plug it in while the ignition is turned on.  

After operations that affect ABS components (e.g. accident repairs), the entire ABS must be checked - see operation "ABS Function, Inspect".