Buses that don't like to shift out of park?

[wirelessguyNY]

So it looks like I've come across this twice already with vehicles I'm looking at buying (one a ford E350 and one an E450) both 7.3L engines not sure about the trannys though.

Symptom: Bus will not shift out of park while the bus is on.
Solution: Turn bus off. Foot on Brake. Shift into Neutral. Start bus. Shift into gear

Any idea what causes this?

I've heard some rumors but nothing definitive from someone who's seen and resolved this issue before. One person thought a bad flywheel could be at fault. Another believes that there may have been some sort of Ford TSB that mentioned a wiring harness needing to be replaced (and that it actually wasn't the physical Interlock/BOO relay that tells when you're depressing the brake pedal) I couldn't find any info on that though.

I'd like to figure out how expensive this could be to troubleshoot and fix before putting an offer in.

Thanks.

[Stuff]

well if its a newer style you have to hit the brake to take out of park and all i can think is the ignition is worn and you cant get that lever to shift to work when running or something.

[freakn]

Is that when bus is running? does it do it when just the key is with engine off? Sounds like an interlock problem. What year of bus are you working on?

[freakn]

The brake interlock does not function until the key is on. Check fuse #1 (15 amp)