Hello Everybody,

Well my troubles are with a Bronco, but hopefully that is forgivable. I have a 1995 Bronco 5.8L, it has an E4OD and push button 4x4.
About 3 months ago now, the truck began to intermittently slam shift between all gears. The shifts occur at much higher than standard rpms. I checked codes - 452, Vehicle Speed Sensor was what came up. I went to the parts store and got me a new one. The truck ran fine for about a week and then started acting up again. I don't think the VSS actually did anything, because sometimes the truck would go 2-3 weeks of acting normal and then go back to misbehaving. I performed an ABS bypass by jumping the harness in accordance with Steve83's supermotors. This verified that the ABS controller is NOT the problem.

When the problem first began the speedometer needle NEVER wavered, not when the truck was acting normal, not when the truck was slam shifting. AFTER I replaced the VSS with a new motorcraft unit the speedometer began to waiver 10-ish mph at around 60mph. I read on another forum where a similar set of symptoms was caused by the Throttle Position Sensor, so I decided what the heck, and replaced it. No difference.

I next performed a review of the wiring and socket that the VSS plugs into. The connector had a broken clip so I procured a new pigtail and spliced it in with some quick connects to make easier to replace. While I was under the truck I decided to replace the MLPS and the connector it plugs into as they were both in sorry shape. None of these operations resulted in any difference.

I conducted a very informal test the last time it acted up, I got pissed and I punched the speedometer. This immediately corrected the condition. Subsequently, I believed the problem must be with the PSOM, so I bought one and installed it this morning. This resulted in no difference.

Since I have checked everything from the VSS to the Transmission at this point I decided to go back to the VSS. I pulled the Motorcraft VSS (currently installed) and measured the resistance across the pins - 1884 ohms. This seams high so I pulled the old VSS out of storage and measured it as well - 1236 ohms across the pins. Since less ohms is better I reinstalled the old VSS. This made no difference, and the truck threw a 452 while the old VSS was installed.

I then checked Transmission fluid level. It is good, and not burned. When the truck slam shifts it is really undriveable, and I have to believe it is bad for the transmission. I am really at a loss and would appreciate any help from y'all. I know this is long, but I want to include as much info as I know is relevant. Thank you in advance.

 

It just might be worth pulling your diff cover and making sure your tone ring - which is beside the ring gear and actuates the VSS - is not all gummed up. It's a possibilty.



The VSS reads the spaces between the teeth. If it gets gummed up and microscopic particles of metal are stuck there, that could give you a bad reading.

Another possibility could be the RABS module (behind the glove box).
You also might want to test the TPS signal - new does not always mean perfect, unfortunately.
And there's the computer... but it does sound like a signal issue is a good probability.

 

My 95 used to do the same thing. That is how I bought it so cheap. I took a chance. However I got lucky because the problem I found is that the previous owner installed steps to get into the cab. He drilled the bolts straight through the transmission harness grounding it out and burning several wires there in the drivers side door sill. Perhaps you can check your harness. Once splicing in new wires and taping everything up besides getting ride of the horrible steps I never had a problem after that.
Good Luck, keep trying.