[xj40] Locking rear wheels when braking

I have a question, the message ANTI-LOCK and a red break light mark are displayed on the dashboard. My brake pads are good. The symptom that appears is the rear wheels locking when braking. Some time ago I replaced the JLM1908 sensor with another used one. Previously, the rear brakes did not respond at all, but now they work, but the wheels lock. Could this be because the JLM1908 sensor is faulty or should I look for another cause?

xj40 3.2L 1993

I take it this car is equipped with Teves III power brakes, in which case there would appear to be an issue with the ABS, but is probably caused by the pressure reducing valve being jammed open.
It could also be that the ABS valve block has a stuck closed return valve so no fluid can be released from the rear brakes via the ABS valve.
You should be able to read the fault codes for the Teves III system.

Plough your way through the linked thread and you should have all the information you need to be able to diagnose and work on the Teves III system.
Teves iii braking system failure - XJ-S - Jag-lovers Forums

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check your parking brake linkage and lubricate ALL. also bleed the rear brake calipers, possible old fluid or air in the lines.

I replaced the brake lines because they were rusty and bled the brakes. The mechanic told me that the rear brake calipers are rusty and that’s why the wheels lock when braking. I need to replace them. will check the relays, maybe they are failing

to @1959fordmodelA
The handbrake cables are new and work properly.

the 1984 xj40 cars had girling brakes