neutralizing problem
#1
neutralizing problem
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.
#2
#4
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.
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.
#7
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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?
#12
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.
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.
Last edited by greystreak92; 12-07-2005 at 11:01 PM.
#13
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donnor
Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W)
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06-25-2004 08:39 PM