Hello everyone, I'm new to this forum so I'm unsure as to if I'm posting in the correct section.

I have a 1995 F-150 XLT, with a 5.8L EFI, 4x4, auto E4OD transmission.
213k miles.

Recently, (today, actually) I experienced a very odd problem. First of all, when I started it in the morning I heard a loud, almost horn-like tone coming from beneath the truck but didn't have time to investigate. Leaving work my truck was hesitating to shift out of 1st gear. I'd reach about 35MPH before it would jerk into 2nd. Then, upon leaving home again later on it wouldn't come out of 1st at all, and the Overdrive light was flashing. I immediately pulled over and started messing with the column shifter. I started the truck again, pulled out, and it was going through the gears like it was brand new. I drove all the way home with no issues. I'm scared to drive it again because I have no idea what's going on with the transmission. After some research I heard a lot about the e4od wiring harness that wraps around the tranny next to the exhaust going bad. Could that be doing this? I understand that it could be a lot of things, but I need some ideas. Thanks!

 

Start by running the self test, do not disconnect the battery until collect any information the computer is bound to have about the problem.

Ford Fuel Injection » How To Run a Self-Test

Post the results here and we'll see if we can help you out narrow down the problem.

 

Hi there, haven't got around to running the self check quite yet as I'm very busy, but I've figured something out. The transmission will only not shift if the orange overdrive light is lit up off. Any ideas?

 

Refer back to the excellent advice in Post #2

The transmission is 100% electronic controlled. The root cause could be any numbers of things. It's your choice: keep guessing or pull the codes to see what the computer is trying to tell you.

 

The flashing OD light is the computer's way of telling you it's detected a fault specifically related to transmission operation and has one or more codes waiting in memory for you to read.

 

Had time to run the self-test today. During the second part of the KOEO test, (Key on engine off, after the "single blink pause") I got the following codes:

452 - VSS/PSOM error (so I'm guessing the speed sensor itself or wiring from the sensor going to the PCM is faulty)

536 - Brake ON/OFF circuit failure/ switch not actuated during KOER test (Just replaced that brake light switch that controls the stop lamps/column shifter, and didn't even do the Key On engine running test??? Not sure about this code.)

Now where do I stand? I've heard a lot about these VSS's going bad and causing tranny mayhem.. but the VSS it's referring to.. is that the one on the rear axle? or???

****EDIT**** : forgot to add that the problem no longer only persists if the OD light is lit up off, it now occurs wether it is on OR off!

 

What codes did you get for the Key On Engine Off tests?

Codes 452 is a Continuous Memory (CM) only code so that makes sense it was displayed after the separator flash.

Code 536 is a not a CM code, sorry sometimes the definitions at the link I previously posted are not 100% accurate for these trucks. I question your flash count.

The VSS is located on top of the rear differential. They rarely go bad. It's usually a wiring or PCM problem. The RABS module or the speed control servo can also cause the VA error code.

First place to start is removing the VSS for inspection. Look for frayed wires or debris stuck to the bottom of it.

 

I was a bit confused by the 536 code as well.
The 452 code however seems plausible.
I repeated the self test many times and the only other codes I got were simply repeats of the previous codes.

I will check the wires going to the VSS tomorrow.
As for the PCM,RABS & speed control servo, do you know the locations of these or how I could check if they are functional? (Other than codes because I did not get any others than what I stated)

 

If all the KOEO tests passed you should have gotten Code 111. I am a bit confused now. There is no way to get CM codes without getting either the System Pass code of 111 or a fail code of some type.

 

Yes I totally forgot to add that in my last reply. I DID receive a code 111 for the first part of the test. In order the codes went as followed: 111,111, (intermediate single blink) 452,536. Sorry about that.

 

Now that makes sense (except the 536 code in CM).

 

PCM and speed control servo location:

courtesy of subford

RABS module location (behind the glovebox:


RABS test port:
c
courtesy of subford

Some great troubleshooting info from Steve83: VSS/PSOM

 

If your speedo is working correctly it's needle always reads steady never jumping about in any given range pretty safe bet the VSS and associated wires are ok.

That'd point to a problem between the PSOM and the PCM instead, either the PSOM the PCM or circuit between them or as mentioned above input from either RABS/Speed control creating problems/noise within the system.

If speedo doesn't work or doesn't work right yea suggests problem is VSS related.

CM code "536" scroll down to section FD90 following link,

https://www.motorcraftservice.com/pu...15/VT16018.HTM

I'd start out by addressing that issue, then move on as/if required.

 

The speedo needle does bobble a little bit when I get up to highway speeds. Nothing crazy though. Maybe a 1-3 mph fluctuation. Would a bobble that small be the VSS?

Also, I did replace the stoplamp switch.. (new switch, new wire installed because one was pinched and broken) and that fixed my column shifter and brake light flicker issues. After installing should I have cleared the CM? I think that would take away the 536 for good. As for the 452.. I'm stumped. I'm hesitant to replace the VSS because I've seen a LOT of people buy a new one with no results. I want to say the PSOM / RABS holds the issue. How should I go about addressing the PSOM/RABS as an issue?

ALSO: To clear the CM, could that be done simply by removing the battery terminals for a few minutes? I'd like to see if the 536 goes away, and if the 452 returns (could almost guarantee it would)

And as always, thank you all for your help thus far. I hope we can get to the bottom of this.

 

Measure the signal to the RABS/PSOM as outlined in the info from Steve83. You can measure the signal input at the RABS test connector.

You can clear the CM codes by removing the jumper during the code display.