Troublesome ABS system
 

The 1990 Golf Syncro I bought a few days ago is fitted with ABS brakes. This system is not working properly.

First of all, the ABS unit is very noisy with the ignition on. It probably is all the time, but I guess the noise is drowned by the engine.

Second, the ABS function really only works every once in a while. When I try to brake hard, I most often lock the wheels, which is accompanied with a lit ABS warning lamp. Rarely does the ABS actually do it's job.

Third, the warning lamp sometimes lights up even though I'm not braking, and it stays lit for around 5 seconds. When I start the engine, it is lit as normal, for a mere few seconds before it goes out.

This car does not have a vacuum brake booster. Instead, it has a hydraulic brake booster with a pressure accumulator, similar to the 5-cylinder turbo Audis, if any of you are familiar with them.

I do not know if the ABS light become lit because of an electrical fault with the ABS brakes, or as a result of a problem with the hydraulic system. I tried to scan the system for fault codes using Vag-Com via the 2x2 port by the gear lever, but Vag-Com could not find the ABS unit (nor the engine's ECU for that matter). NiwAsle does not have anything on the Golf 2 either, and I feel that Haynes is useless... :(

Any tips or hints on how I should attack this problem would be great.

abs
 

Hi, not sure if this helps it was on my mk3 vr6, but the symptons sound the same, turned out to be one of the wheel sensors in the end.
good luck!

Is it the pump that's noisy?

Yes, the pump is noisy. It sounds like an old, worn out electrical motor, which it probably is as well.

My guess would be that the pump isn't giving the pressure that it should so therefore the ABS light is on....