I have a 1994 bronco xlt 351 e40d transmission.My truck will go in neutral going down the highway.I have replaced the trans,rear end,speed sensor,cruisecontrol mod... The dealer is no help.I love my bronco but I cant fix it,very scary.If my cruise is on it will shut off first.But if is not on it will give me no notice.Please help.

 

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Thank you I sure hope someone can help me with this problem,Its to the point that I cant drive it, I am afraid it is going to happen in vegas,I could get in a wreck.

 

First off, welcome to FTE and the Big Bronco Forum.

Have you checked to see if the computer codes will give you any insight to the problem? If not that should be your next step. The problem sounds like a faulty MLPS (Manual Lever Positioning Sensor) or BOO (Brake On/Off) switch. If mis-adjusted or defective, the MLPS will cause you no end of headaches. The BOO switch tells the computer when the brake is applied so it can tell the transmission to go into "cruise" mode. This is NOT a setting related to the cruise control but rather a mode of operation for the tranny itself.

If your EEC computer generates two-digit error codes keep an eye out for codes 67, 74 and 75.

If it generates three-digit codes, watch for codes 528 and/or 629.

This is not to say that there may not be OTHER codes present but these directly pertain to the two components I mentioned.

To check/pull codes, check www.fordfuelinjection.com or your Haynes service manual.

 

thank you for the advise.I will look in to that,the last time the codes were checked,nothing was coming up,but I will have them checked again.

 

whare is the manual level positioning sensor located? I may have replaced it.

 

Its the multi-position electrical assembly mounted to the transmission that is activated by the shift lever. It IS adjustable so replacement doesn't guarantee that it is sending the correct information through.

 

Thanks again.I did replace that but maybe I didnt adjust it right.Also some one told me that it it could be my transfercase going into to neutral.Do you think that is possible?

 

Sure, anything is possible. Is your T-case manual or electronic shift?

 

yes my transfer case is elect.

 

one more thing,I baught my bronco from my sister,she said she never had this problem till she got the rear end rebuilt.when I baught it the rearend she had rebuilt,was destroyed,ever since I had it rebuilt I keep getting metal shavings on my speed sensor on the top of my rearend.I have had it looked at atleast 6 times from the shop,they cant seem to fix it,when it neutrilizes if i pull out the sensor out and clean it the truck will shift again for a short time.could the problem be my speed sensor/rearend?

 

Absolutely! Sounds like whoever rebuilt the rear end set the gears up wrong. Thats the most viable reason for the continued wear on the rear end and the build-up of metal shavings. When this happens the VSS (Vehicle Speed Sensor) cannot "read" how fast the gears are spinning to send speed info to the computer. When this occurs, the computer goes into what is commonly referred to as "limp" mode which does not allow the transmission to shift out of first gear. Chances are, your truck isn't going into neutral at all but downshifting to 1st and staying there. (It may FEEL like neutral since the truck slows down and the engine begins to race when its forced to drive the truck in 1st gear at 60mph)! This "limp" mode forces the truck to slow down and keeps the transmission from self-destructing because the computer has no idea how fast the truck is going and can't tell the tranny what gear to be in safely. So, it forces it to drop into first gear and won't shift out until the VSS problem is rectified. If the VSS is getting covered in metal shavings repeatedly because of a problem with the rear end gearing, its not only a possible cause its the most probable cause.

This also helps explain why the cruise control will shut down when this happens. The cruise control uses the same speed information from the VSS to maintain speed when the cruise control system is on. If it no longer has any way of knowing how fast the truck is going, the fail-safe will be triggered in the C/C system and shut it down.

 

to greystreak92,thankyou for your information,I guess thats the information i was looking for.That is the problem I kept going back to.I will have to get another rearend,maybe ill get one out of a junkyard if I have to.Thanksagain,I will let you know how it turns out.

 

Joey,

What year is your truck and where are you? I may be able to help with a replacement rear end. Send me a PM or an email and we can discuss it.