Vehicle: '97 Chrysler T& C with 3.8L engine, FWD w/ Leves ABS and Traction Control, 138K miles
After a few months of spongy brake pedal and an intermittent, but rare, ABS warning light, I borrowed a Snap On MT2500 and bled the brakes (1st Manual, then with scantool, then manual again.) No real improvement. So I replaced the master cylinder. An hour before replacing it, the scantool bled the brakes properly - activating the ABS pump, values, etc, but immediately after replacing the master cylinder the pump wouldn't activate. The ABS fault code was 30 (which is something like " ABS pump circuit failed to activate" ). Double checking the part, I found I'd installed the master cylinder for the AWD, not the FWD. So I got the right part and repeated the process. Still the pump failed to operate. Checking the ABS wiring. It looks fine, the input voltages checked out, and the pump would run when jumpered. I cleared the code several times but typically the code would reset (code 30) immediately on starting. However every dozen starts or so the ABS light turns off normally and doesn't come back on until I reach 25 mph.
Question 1: Any suggestions on what's going on with the ABS?
Second problem: (perhaps related): During all the brake work I noticed the one of the proportioning valves was leaking quite a bit at what I assume is a pressure release valve. So I replaced the valve assembly. After bleeding the brakes manually several times, when driving the brake pedal becomes gradually firmer then locks the left front brake entirely. Once locked, I have to open the bleeder valve or pump the brakes 20-30 times with the engine off to release the brake line pressure. Using the scantool to cycle the ABS values doesn't seem to do any good. Once the pressure's released the wheel cylinder can be retracted with normal pressure so the caliper's OK. Brake fluid is simply getting trapped in the brake line. I'm guessing this explains the leaking proportioning valve.
Question 2: Does this sound like the master cylinder actuator rod needs adjustment, there's a stuck valve on the ABS system or something else?