I’ve had a very weak pedal on my truck like a master cly that is bypassing in a regular system. Changed the master cly and still the same. The ABS and brake lights are now on because the new master cly low brake fluid level is not functioning. I put the old master cly on and the lights go off. However, with old or new master cly, the brakes will lock up on a hard stop. So, I suspecting the ABS module is the problem. This is a pretty simple ABS module with only two lines going to the block. It may be just rear only . There is a speed sensor on the left front wheel, though. My question is do I just change the electronic part or the whole complete pump. I’ve got one coming from eBay because a new one is $500 plus. Any help is appreciated.