Any method to test the ABS hydraulic unit

[power_up]

Hi all,

My 1st post in the new forum. Hope all you goes well.
Had my 1991 C2 three years without ABS. Many lock up tyres in these period.
No warning light. Had interchange a known ABS control unit and those relays but no luck.
So now suspect the ABS hydraulic unit. Is there any method to test it is faulty?
If I buy a used unit, any bench test can confirm it is a working unit? Is the unit compatible to C2 and C4?

Thanks.

[Steve]

Hi,

I've not used any of the aftermarket scan tools, but the Bosch Hammer will interrogate the ABS system to allow some troubleshooting and this is done in-car. That said, I'd certainly make sure that all the wheel speed sensors are spotlessly clean and the sensor wiring has proper continuity to the controller before considering replacement.

C2 & C4 ABS controllers are different and should never be interchanged.