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.

I just talked to a dodge tech Freind of my step son and he says I have contaminants in my brake system that have swelled up all the rubber hoses and seals. So I need to change my master cly and ALL of the rubber hoses and calipers. He’s said that they are constricting the flow and it it’s not the ABS module. Anyone ever heard of this ?

I know old rubber will do that and it's always a good idea to replace them. I have a '07 1500 too and I have warning lights everywhere on my dash but so far it hasn't broke down on me

The tech told me that the sure fire thing to look for is the rubber seal in the old master cly cap. If it was distorted or swelled, then it was certain all the rest of the rubber in the system was swollen and needed replacement. Well, the cap seal looks brand new and no swelling. I talked to a couple of freinds that have both been techs on all kinds of cars at different shops. They both said I simply have air in the system and it’s very hard to get out of an ABS system. They say to gravity bled or pressure bleed. Neither one has ever heard what this dealer tech claims. One said that it was a ploy to be able to replace a lot of parts and charge a lot of money to fix the problem when you just properly bleed the brakes. Sounds like something a dealer would come up with. I have been looking on the dodge truck forums and soft brakes is a common problem. Fixes are as many varied as the number of replies on the thread. Everyone has a different fix. I’ve alwas been told you should never just force the disc brakes cups back in so you can install new pads because reversing the direction of the fluid harms the ABS valve. One guy told to get a pump that reverse pressures the system to get the air out. I’m still looking for a fix.

Contaminated fluid is a thing and checking the cap seal is a valid inspection.

Trapped air is also a thing. A scan tool that can cycle the abs valves is useful. Or, panic stops on a loose surface to force the abs to cycle.

Yep^^^ and Yep^^^

We’re going to reinstall the original master cly to see if it works better than the last new one. The cap seal is still good and the low fluid level switch works on it and it turns out the lights. I’ll check with my friend about the scan tool to cycle the abs valves. Thanks. A panic stop results in all the brakes locking up.