I am back again. Thanks to everyone a while back when I was doing the big swap. I have a 94 F150 that was a 5.0 with the 4rw70. I swapped in a 5.8 and E40D from a 95. I had another 94 that was a 5.0 and E40D. I used the computer and wiring harness from that truck. I also swapped in the solenoid pack from that 94 because of the differences between the 2 years. It runs great and I love the added power but the transmission is driving me crazy. It can shift fine for a couple weeks and then it goes into limp mode and shifts crazy hard. Sometimes it does it once or twice, other times for hours. I have stopped at a corner, shifted it into park and back a couple times and then it's fine. Sometimes, I shut the engine off and restart it and it's fine again. Sometimes it does it all day. I have checked the cab brake light which can cause other issues. I keep getting a code for the VS sensor on the rear end. I installed 2 used ones. Cleaned the ring in the differential which really wasn't dirty at all. Installed a new VSS, same old symptoms. Intermittent hard shifts. I have removed, cleaned, greased all connections. Made sure the shifter switch is adjusted correct. I drove it a month ago and it was really strange, wouldn't shift out of low, shifted it into 2nd manual and when I go to drive, it just free wheels like it's back in low or neutral. It has only done that once. Sometimes it doesn't shift into low when I stop at an intersection. I am thinking it is the shift solenoid hanging up or a valve body issue. Can I remove and clean that solenoid or does it have to be replaced? Same with the valve body? It holds 20+ qts. or fluid so I don't want to keep taking that pan off and on if I can help it. Thanks in advance.

 

The sensor in the differential is not directly related to the signal the EEC-IV is seeing. The signal is converted from a sine wave signal to a square wave signal at the PSOM.

I like testing, so I would test that signal at the PSOM. Might as well do both if you are there.

I have a 95 and the way I tackle anything is I just assume the old part is bad. I never tested mine, but took out the PSOM to inspect the board. Yes, there was a capacitor leaking so I sent it out locally to get it fixed. No reason to make a test if you can see the problem.

If you have not checked for codes, you should.

 

It keeps showing the 452 code for VSS. I have heard about the PSOM, but I'm sorry that I really don't know much about that. Is that behind the gauges somewhere? Thanks.

 

Have you replaced the MLPS?

 

The MLPS is from the parts 94 that I also used the computer, harness and shift solenoid from. So, I have not replaced it with a new one but have checked the adjustment on it to make sure it was properly aligned. The whole intermittent problem I have leads me to believe that something is sticking. If it was a "malfunctioning" part or sensor, why does it often stop shifting weird when I stop and shift in and out of gear? That is why I am thinking that it is a dirty/sticky shift solenoid or valve body. But, I am not a transmission guy by any means. I do appreciate the suggestion though, I knew I would get some solid info on this site.

 

It's mounted on the rear of the speedo module, see the video below. This module unplugs from the front of the dash cluster so you don't need to remove the whole thing, just remove the dash surround trim, then the clear instrument bezel to gain access.

The speed signal comes from the rear diff to the RABS module and then on to the speedo where it is processed and then sent to the PCM, so there could be an issue anywhere along that route.

 

So the whole piece he shows here is the PSOM? With the PCB and LCD attached? Would the PSOM be bad if all of my gauges and speedometer work? Although my oil pressure gauge just instantly quit a couple years ago. I since put a mechanical gauge under the dash.

 

One other thing. The truck shifted fine when I had the 5.0 and 4RW70 in it. Problem has only been since I put the E40D in so I am don't think it can be anything with the truck itself, but probably the transmission or wiring that I had replaced when doing the drivetrain swap.

 

The mlps go faulty and intermittent due to water intrusion.

 

The PSOM is the circuit board mounted on the back of the speedo that is attached to the odometer display.
It's not likely it has an issue IMO, it's more likely that in changing wiring harnesses the speed signal no longer makes it to the PCM

 

OK, thanks. But would the wiring harness be so intermittent? I drove it yesterday, shifted fine when I left home. Stopped at the first stop sign and then it went into hard shift mode. Stopped at a second sign, shifted hard again. Stopped, shut it off and put in gas, then it shifted fine all day with multiple stop and starts. It never bothered the rest of the day. It is such a nice truck, but this is really annoying when it shifts like that. Thanks for your continued great advice!

 

I would strongly suggest opening up the computer & looking for leaking capacitors.

Long story short, chased plethora of trans codes to cure hard shifting in my E4 up to rebuilding it.

Still did the same things.

Fixed leaking caps & replaced PSOM to correct.

 

I tend to make decisions on facts/tests.

IF the EEC-IV is having problem with the speed sensor, then I would invest time and effort to check this signal. Since the speedo is not giving you problems, I would not invest time on the actual sensor at the differential [yet]. My assumption is that the speedo and RABS modules use the sine wave signal from the differential and the engine uses the square wave signal that the PSOM sends out. If the sine wave signal was poor, then I suspect it might effect everything. You know, garbage in/garbage out.

Can the PSOM change this sine wave to square wave do a poor job? Can't see why it could not. If indeed that converter in the PSOM is bad, would it affect the speedo/odo or RABS? I doubt it.

This is an old truck and sure, all the components are tired and worn out. Not a bad idea to replace them, assuming you can get good parts. I still would focus on the speed signal going to the EEC-IV. I can't see why the computer would set a code if there was not a problem. With that code, it will shift hard.

If yu got a tester, it's just too easy to make a test of the speedo signal. If you are doing that, check both, the sine and square wave.

 

I have a hard shifting problem on my '95 F150 with 302 and E4OD. This just started, had been shifting just fine for many years. I am getting code 452 but the speedo works just fine so I am assuming this means the sensor in the rear-end is OK? How do I test the signal going to the trans to see if the PSOM is the problem?

 

I have a spare instrument cluster, cant I just swap it out to see if the PSOM is the problem?