I have a 1994 Dodge Dakota with a 3.9L engine and automatic transmission with 255,000 miles on it. When approaching a stop sign and applying the brakes, I heard a pop, followed by the brake pedal going to the floor. I was going slow before applying the brakes, and the truck did stop, but I immediately limped in back to my house about three blocks away, parked it in the driveway, and am trying to decide how to proceed. It's OBD1, and I have no OBD1 scanner, but I feel certain that the problem is either the master cylinder or the ABS module. Yes, the ABS warning light is on. I'm not getting any pedal pressure with the engine running or off, no matter how many times I apply the pedal, and no signs of leaks, but the brake fluid reservoir is low. The parking brake cable broke over a year ago, so that doesn't work, either. The brakes worked perfectly until this happened, no typical ABS problem hints. The ABS on this vehicle is only on the rear brakes, anyway, and I really don't need that feature, but I don't know how to bypass it. The master cylinder is easy to replace, but I'd rather not replace it if that isn't the problem.
are you sure you didn't pop a brake line?
Good point, metal lines are suspect on anything that old especially if it's in the rust belt.
Yes, I'm sure. That was my initial thought, too, but everything that should be dry IS dry. Must be an internal leak.
If there are no leaks at brake hoses or calipers and wheel cylinders you probably have a leak in the master cylinder. If you have power brakes the fluid would be pulled into the brake booster and burned in the engine. If that's what's happening it will wind up damaging the booster.
On a vehicle that old you should replace all the rubber brake hoses anyway if it has not already been done.
No apparent leaks anywhere, Wheel cylinders are dry, too. Wonder why no one suspects the ABS module. Thanks for your input.