'99 F-250 problem

[67galaxy]

I have a '99 F-250 SD w/ a 5.4, auto, supercab, & 4x4, 59k miles. Here's my problem, ABS & service engine light came on, engine revs to 4,000 RPM in 1st gear, changes HARD into 2nd, slips sometimes in 2nd gear also. Speedomter also stays @ 0 till around 30 mph then jumps up to normal. All this started at the same time. Trans. has never been abused, with reg. maintainance. Any suggestion and/or help would be greatly appreciated.

[ModMech]

I believe they use a digital VSS signal processor between the trans and the speedo/EEC. It sounds like that may be defective, which would explain ALL your symptoms.

[97chevyman]

speedo sensor, the reason your abs light came on is because i thinks one of your abs sensors are bad because the speedo sensor is saying something different than the abs sensors. new sensor would fix everything. The pcm uses the speed of the truck and the amount of throttle to judge when to shift.

[67galaxy]

Thanks for the help guys! Turns out it was the rear end speed sensor.New sensor, grease change, reprogram computer and it's good as new.