So I'll start with symptoms, bear with me, I've gone through alot

Truck runs great
Tranny shifts very firm 1-2,2-3 and 3-4. Have to let off accelerator to get it to upshift most times, that or nearly red line it.
Shifts firmly on the down shift 3-2 when coming to a stop.
Fluid is good, mercon* (will be swapping to mercon 5 soon as this is fixed)
Speedo works but is at least double the actual speed, but it's solid not erratic
Checked and cleared codes, 452 recurrs. Vss signal bad


So here's what I've done so far
New Vss , no change
Unhooked tps, slightly worse/no improvement
Unhook vss, did the same as tps except the speedo quit working of course
Inspected psom for damage, appears good and clean
Inspected wires and connections on mlps,psom,tps,firewall con.,vss, etc etc... no corrosion or damage


I'm pretty convinced it's an electrical issue but who knows after what I've gone through. Maybe the valve body but it seems like it would be more isolated in the gears to me. Somebody shed some wisdom on me

 

Assuming you installed the right VSS, that eliminates it as the cause.
What lead you to do that? You would have had better results by cleaning the windshield. That also wouldn't fix it, but at least your windshield would have been clean.
So it's probably not the sensor.
Did you inspect inside? Were you able to electrically test it to see if it's putting out the correct signal? If not, you didn't do anything useful with the PSOM.
Did you check each wire for continuity? How about short to power or short to ground? If you didn't check each of these your inspection was not at all useful.

How can the valve body cause the speedo to read wrong and set a code 452? It's not possible that your problem is the valve body, or for that matter, anything else inside the transmission. Your problem is that the PCM isn't getting a good speed signal. Since the speedo is reading twice what it should be reading I suspect you have a bad PSOM.

 

Thanks for the bluntness. Yes my next step was to start ohm testing everything but thought I'd see first if someone was familiar with this exact symptom set, as after tons of research nobody had the exact same symptoms.

The psom has been my suspicion the whole time but I'm just getting familiar with the type testing it takes to verify that.

And lastly as a tech, the first thing to do is visually inspect all connections and wires, saves a lot of headache in the long run.

Thanks for the pointers

 

Continuous Memory DTC 452 indicates the PCM detected an error in the PSOM output signal during the last 40 warm-up cycles.

Possible Causes:
Damaged Rear Anti-Lock Brake Sensor.
Damaged PSOM.
Damaged harness circuits.
Damaged Powertrain Control Module (PCM).

Key off.

Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.

Install breakout box, leave PCM disconnected.

Measure resistance between Test Pin 3 and Test Pin 6 at the breakout box.
Is resistance between 21,000 and 55,000 ohms?

 

I'll find a diagram for the pins, can I do an ohm test with a multimeter between those two pins? Is that the vss feed? Thanks subfors, I've followed your info for a bit on the subject

 

The two pins have the same number at the computer plug.



/

 

So I tested the psom, it was bad, replaced it with a tested good one, now it reads accurate speeda, but the hard shift issue persists, what should I test next?

 

Update
Just ohm tested the new vss I bought awhile back, it's at 1980ohms. Now I'm getting conflicting answers on what it should be, some say 1400ohms is right, others say between 500 and 3500 is acceptable.... any thoughts?

 

I don't know about the ohms but when I had to replace my vss I don't think it was actually the vss itself. My connector was fried so I spliced in a new one.

 

Well I'm gonna try to find how to test the abs module. I'll keep updates