91 Cherokee ABS problem after replacing rotors & pads

Brakes were working fine except for the warped rotors. Replaced the rotors and pads as usual. Then the ABS light and brake light came on. I pumped the brakes and got the lights to go out, but the pump motor would now run for about 5 seconds every 15 seconds, even if you didn't step on the brakes. Drove it the next day and now the ABS lights stay on and the pump runs all the time. What went wrong? I pushed the pistons back in the callipers as I have done before using a C-clamp, but never had this outcome. Did I screw something up? Any help would be appreciated.

Thanks.

Jim

#1 Check And See If The Abs Sensor On The Wheel You Replace Brakes On Is Out Of Alignment.#2you Might Have Air In The Abs Pump,you Can Bleed It Out,were The Brake Lines Attach To The Pump, Should Be 3 Line.these Procedures Are Found In The Haynes Jeep Repair Book.worked For Me.

When pushing the caliper pistons back to replace shoes, the brake line should be lightly clamped to prevent fluid from returning up line. Open the bleed screw to allow the piston to move.

This is to prevent old fluid and any contamination from being forced into the mastercylinder or valves.

It is especially important on vehicles with ABS!!!

I suspect what may have happened in this case is something has stuck in one of the small valves in the ABS unit and will not dislodge.

Try removing most of the brake fluid in the master cylinder reservoir (use a turkey baster) and replace it with NEW fluid. Bleed all the brakes at all wheels following the proceedure and sequence in the manual and DONOT let the master cylinder run dry during bleeding.

Sorry to say, many times the only cure is a new ABS control valve.

JD