Hey guys, I have a 1994 F150. It has 225,000 miles on it. It has had the trans. dealer serviced before I got the truck (It had 220,000 on it when I got it) I don't drive much. Anyway, I changed the fluid not long after I got it. I drained the torque and took the starter off and turned the torque conv.to allow me to put 4 qts. in it and replace the drain plug so it was NOT started dry. Anyway, that was about 5,000 miles ago. It has been great an no problems whatsoever but all of a sudden it "jerks" when shifting from 1st to 2nd if you take off slowly and easily. It seems to do better if you drop the hammer on her. It is a 351W and is running fine all but the trans problem. It did do something else kind o weird not too long ago. It just died at a light, but started right back up. It did that 3 times in about a 6month period. I had my brother scan it with a good Snap-On scanner (one of the late model/high end scanners) and all it said was the speedo wasn't working something like an open speed sensor or something like that?? It was wrong cause the speedo works fine. Anyway, the light ain't blinking on the shifter like I've heard of before on some problems. It just does this jerking thing. It is full of fluid (The last time I checked it, a few weeks ago) Any and all help would sure be appreciated. I've heard they make some real nice upgrades for the rebuild kits on these things. I LOVE my old truck and want' to fix it. Please help FTE folks I'm kind of worried about my old truck. Thanks again in advance guys.

 

Hey guys, I just wanted to bump this to the top and ask about how much I'm looking at if I have to have the trans rebuilt? Its a 2WD truck. Thanks guys.

 

Need more to go on re-read the codes post them here, speed sensor issue could easily cause the symptoms you describe.

No fancy coder reader required> Ford Fuel Injection » How To Run a Self-Test

Based on what you stated so far, no it does not sound like a fault in the trans itself.

 

This is your problem. It's not the speedo it's the speed input to the computer that the code was for, that signal is sourced from the PSOM so you either have a wiring issue between the dash and he PCM or a bad PSOM. By the way PSOM stands for Programmable Speedo Odometer Module.

 

Yup could be as simple as bad connection, PCM pin 3 dirty/corroded.

I'd test the circuit while I had the connector off.

 

Where is the plug you guys are talking about?? Is it on the top of the rear diff housing?? I had heard that the speed sensor or whatever is in the diff housing? I did replace the speedo cluster a couple of years ago with a factory tach one but it has worked perfect for all this time. Like I said I dont' drive much. I've had this truck for 6 years and only put 5,000 miles on it. My work is right next to my house and I don't have to make many truck runs. How do I do a speedo self test also. THANKS SO MUCH for any and all help. I don't have the codes my brother pulled up and long story short don't get along with him real well so I'd rather figure it out on my own

 

I did let the truck warm up today for a long time and check the trans fluid. It is full and clean and smells good. It does have a factory Ford trans cooler on it. Do yall think I need to pull the rear diff cover to check and see how clean the reluctor ring is or the sensor??? Is this where the speed sensor is located? What about them plugs or other stuff?? I need somewhere to look for this problem. Thanks again guys.

 

I'd be helpful if you could follow the instructions in the linked to page, post codes you get in return.

The fact you state the speedo works fine suggests the VSS the reluctor ring and associated wiring to the rear axle is fine, based on comments so far sounds like the problem is between the PSOM and the PCM.

Keep in mind VSS feeds PSOM PSOM feeds PCM (but not limited to).

In post #3 ^^up there^^ the blue text in it is clickable, a link to instructions how to run a self test no code reader needed....that way don't need your brother either (little joke there).

Knowing exactly what codes its throwing will be at least to an extent helpful beyond what you've already stated.

If you'd run the self test post the results that'd be great.

 

Thanks Dan, I must have missed that link the first time I read it and then I didn't go back to re read. I just looked it over. I'll re post when I find out more. I thought it might be in the speedo cluster cause of changing it out. Anyway, thanks for all the help and patience. I'll run that self test and re post back. Thanks again.

 

Ok, I did the self test and this is what I found (maybe if I did it right. It blinks fast) anyway, KOEO code#452 KOER 653 853 6732 I am not sure about the last code cause it has 4 digits in it??? The 452 said something about VSS signal too small. The 653 said TCS (trans switch) did not switch during KOER test. Does this help you guys to help me any at all??? Thanks for any help

 

Yea will be all three digit codes, there is a single flash KOEO to CM separator code in there too (separator code is 10) however it is simply signified by a single flash using that method.

Should have mentioned no need for the KOER test just yet, mostly interested in the KOEO self test results and any CM codes stored at this point.

Anyway yea 452 is a CM code and = "Computer detected an error in the VSS or PSOM signal during the last 80 warm-up cycles".

Computer doesn't know where the trouble originates reason it lists both VSS and PSOM.
Again due to the fact you state the speedo works fine that suggests the VSS is fine.

So boils down to what Conanski pointed out, problem with the connection between the PSOM and the PCM or the PSOM itself as the problem.

You're gonna have to test the circuit and make sure connections are clean and tight.

Make sure the connection to the PSOM is tight and clean as well as the computer harness connector, I will include a diagram so you know which pin, the wire to it, is the one in question. You'll also want to test the circuit between the two (make sure the wire is good) running between the two and while you have the connectors off.

Sounds like a pain but really not to bad and gotta be done to move forward.

PCM pinout > 1992-1993 Ford Pickup PCM Pin Out Chart (4.9L, 5.0L, 5.8L Only)

Note pin number "3" in the above

Connector layout > Ford Fuel Injection » EEC Computers shows which pin is pin 3 on the computer/its harness connector.

I don't have the fancy diagrams Subford posts and haven't had much luck finding an example but for the PSOM you'll wanna look at pin 7 should be a gray-black wire (gray wire black tracer).

PCM is mounted in the firewall,



Large connector at right.

The PSOM you should be familiar at least to a degree,



Above shows PSOM separated from speedo.

 

Thank you so much dude. I'll try to check this out tonight when I get home. I do have a couple of questions though. Is the PCM sometimes also called the EEC?? And is the PSOM removable from the speedo itself and replaceable?? I thought the one that's in there might be bad?? As I said, I did change the whole cluster to gain a tach and just replaced the whole thing. I still have my original one. Thanks again for all the help. I'll get my OHM meter and check the wire you told me to check.

 

Heck yea if you still have the original one swap it out see if that corrects the problem, that would be easier save off circuit testing until proves needs it.

If swap it out clear the codes, code returns then you'd have to get deeper into it.

You can remove the speedo from the cluster change it only, swap full speedo or just the PSOM. Myself I'd just swap the speedo.

Remove the clear lens via bolts around perimeter, remove the gauges both sides then the speedo reverse to re assemble.







after removing lens just lift gauge assembly off of housing,



each side of speedo, then lift off speedo itself swap in your original.

You'll notice the gauge modules are friction fit pin and socket to the housing, they retain the center speedo section when in place no tools required.

As you'll note in the previous post the PSOM itself can be swapped out from rear of speedo head too (don't do so now as would negate your test, its the PSOM that is in question). Just wanted to mention it, easier to follow when see it first hand and all.

You can clear the CM codes that are stored two ways, disconnect the battery for a few minutes or start the self test then pull the jumper once it begins. Problem with disconnecting battery is loss of adaptive strategy, clearing codes retains it.

And yea EEC and PCM same thing to a degree, EEC = "Electronic engine control" say pre 89' model controlled engine function only. PCM = "Powertrain control module" 89'ish and later year models when computer controlled transmission came into play, controls both engine and trans.

So when posting in threads about pre 89ish model year trucks I tend to refer to it as the EEC, after 89 tend to refer to the computer as the PCM, I'm not sure of the exact date/model year but somewhere around there.

 

When you remove and then reinstall the cluster make sure the connections are clean, where the connectors plug into the back of the cluster.



Make sure the contact points on the ribbon are clean and that those connectors are fully locked into place. If contacts on ribbon appear dirty or feel connection might be questionable, use a pencil eraser to gently clean them.

POSM connects at the center and if you had a connection problem at the PSOM end of the circuit that is where I suspected it might be, the harness connector to the PSOM or a bad solder joint at the connector itself. Might be worth a good looking over once you have it in hand, bright light magnifying glass.

 

THANKS so much!! g That's what I'm goin to do. I just talked to the transmission guy and they said that its cheap and worth the risk of changing the VSS. Its on the diff and my cost at the parts house is $15 so I'm goin to change that first and then on to the cluster. I just changed it to gain the tach and its been so long I can't remember if I used the original speedo or put in the one that came in the complete cluster? But I have another one regardless so I'll try both of these solutions. Like I said the original owner took it to the dealer for everything and had all fluids changed according to the book. The fluid looks and smells good. Thanks again, I'll let ya know as soon as I know what's going on.