I recently had a problem with a 1994 B350 van in which the left front brake would not release. I was on a trip and noticed that during a stop it felt like the ABS was activated. I could feel significant pulsation in the brake pedal. I was making a normal stop on dry pavement and there was no obvious reason for the ABS to become active. I continued driving a short distance and noticed that the left front brake was becoming hot. I initially thought it may be a problem with the calipers, however after removing the tire there was no evidence of a caliper problem. Even after stopping the vehicle and raising the front end, the brake would still not release, even with the engine turned off. I finally disconnected the connector under the hood that goes to the ABS and the brake released. I left the connector disconnected and continued driving with no additional problems. During the time that the brake would not properly release, the ABS light and brake warning light DID NOT come on. These lights only came on after disconnecting the ABS unit. Additional work eventually showed that the left front wheel sensor voltage was MUCH lower than the right wheel sensor voltage. It was well below the required voltage. The left front wheel sensor has been replaced and the voltage is now similar to the right wheel sensor voltage. It seems to be working fine, however the ABS and brake warning lights are still on, even after driving at highway speeds. Do I need to have any codes cleared to reset the ABS unit so the lights will go off? The other question I have is how can the ABS system continue to maintain brake pressure when the vehicle has come to a complete stop and the engine is turned off? Is it possible that the isolation valve remained closed and the brake fluid could not flow back to the master cylinder? I am concerned that there may be a problem with a relay or a solenoid. I think the left wheel sensor may have been responsible for the activation of ABS when normally it never would have activated based on the normal stop I was making, i.e. no hard braking. I am now trying to determine if there is some other problem that caused brake pressure to be continually applied to the left front brake. Any comments would be greatly appreciated.