My truck has check engine light on 2 codes found p0455 & p1780, drove to store today come out and put into reverse truck hesitated like as if the brakes were applied finally was able to move truck put it into drive an dove home about 3/4 of a mile put into park waited 10 min. Went out back out and started up truck tried to back up did the same thing it did at the store only this time brake pedal went all the way to the floor like as if it lost all it's vacuum
Shift problems on 1999 Ford F-250 Super Duty
by Visitor in Salt Lake City, UT on February 19, 2011
1 answer 1 comment
ANSWER by DaveJM , February 20, 2011
P1780 is related to a fault with your O/D switch; P0455 is an evaporative emission system leak (like - make sure your gas cap is secured). Neither concern really apply to your symptoms. I would concentrate my diagnosis on your brake system. Your master cylinder could be suspect. Have your hydraulic and power assist brake systems checked immediately by a professional who can really drill into what's going on with your truck and keep you from having a serious safety issue.
COMMENT by Visitor , February 20, 2011
it acts like a vacuum modulator ,but I don't see one is this vehicle supposed to be equipped with one. I checked the brake master and the vacuum booster both are performing correctly