That scenario sounds reasonable. I will check into the PSOM on my truck. I will re-post an update early this coming week on what I found out and what action I am taking on it.

Thank you for the continued dialogue with me on this issue.

 

Thank you for the input. I think I may be getting real close to culprit problem that has dogged me for quite some time. I will re post with an update this coming week as I take the next step with the PSOM

 

Do you remember the shop you sent yours to, and the cost?

 

Nope. The VSS creates a square wave. The PSOM converts the square wave to a digital MPH signal that the PCM can use.

 

Typically, sensors only send out sine waves. They are just magnets that watch a piece of metal go by. That metal causes the magnet to make some voltage. Yes, I am being very simple but that is how my brain works. There are many other electrical engineers that can explain it better than me.

I stand by my original statement. The PSOM changes the VSS sine wave to the 'digital' square wave signal.

 

I pulled the speedometer cluster out of the truck tonight. I found a local company that tests and rebuilds the PSOM. I drop it off tomorrow morning. I will let you know the outcome when I get it back and re-installed.

Craig

 

Please keep updating this thread. I have the exact same issues. Even spent 1800.00 to have the trans rebuilt. Didn't help. I've also done the same replacements you have. VSS, MLPS, solenoid,filter,fluid. Thanks.

 

It is fixed! The problem with my truck was the PSOM (behind the speedometer cluster).
The symptoms: Erratic hard shifts, both up and down. The truck at random would "pop" into a nuetral type state of operation. The transmission would also stretch out first to second up to 3,000 rpms, then slam second gear hard! I could shift the truck with easing up on the throttle but it still hit gears hard!

Other symptoms include transmission not down shifting properly when coming off the freeway (would stay in high gear and "lurch" at the stop sign), and would also either stay in higher gear when rounding a corner or sometimes pop into the "nuetral" type mode.

The VSS (vehicle speed sensor) tested good and the speedometer still worked during all of this. This really threw me off because everything I have learned is if your speedometer works, your VSS is good.

I had my solus pro hooked up to the truck and noticed when the transmission acted up, my speed dropped to zero on my test equipment but not the dash board.

I ohmed wires to the RABS module, and they were good. So I did figure the problem was between the speedometer and the pcm (but I thought it was a bad wire only). But I was off a little bit. I learned with help from Mark Kovalsky on this forum that it was the PSOM module. I found a local guy that tested mine, yep it was bad....rebuilt it and re-installed tonight. Truck drives, shifts, has power like it has not had for a while.

All this said, remember this problem was "intermittent" which made it tough to figure out. Hats off again to Mark on this forum. Hope this helps!

 

Thank you Mark for all your help. Been chasing this problem for a while. You have no idea how much I appreciate your help!

 

Check out my reply on this thread. My truck is fixed. It was the PSOM

 

I have read forums for Decades, and you will see people Beg, Kick, and Scream for Help with their vehicle issues...
Suddenly, An ARMY Descends, an Army of BaddAss Skilled Motor Heads , Do it Yourselferz with good input, and so on..
. The Vehichles Owner becomes enveloped by People who Selflessly want to Help. Plus the Challenge , Education, Team Effort, and Sense of Accomplishment are always a Good Feeling....
I've seen threads go on with hundreds of hours and years of input..
. Regardless, It is Very Rare, that people show proper Respect and or Thanks for said input and help..
The Worst part... They ALMOST NEVER RETURN TO SAY IT'S FIXED AND THIS IS WHAT THE ULTIMATE ISSUE ENDED UP BEING...
You, My Good Sir... You were Great at explaining your issues, not leaving any aspects out due to FalsePride or whatever, which surprisingly keeps many from mentioning all aspects.. not that there was any issue with FalsePride here..
. You Explained Your Issue and Related. You took advice , Discussed it and proceeded to follow through with each stage and replied with results...
. Long post Short..
. You actually came back and Said it was fixed... and what the Gremlin actually was..
. Regardless of whether that is the fix for my car, It is Great to see someone Actually, Close The Case and Share the Information... Instead of Forgetting those who have participated in your journey..
. Thank You...
\m/

 

Thank you for sharing your kind words. I hope others will stumble onto this thread and fix their truck issue as I was able. Have a great day.