Code 452
Thread Starter
|
Freshman User
Joined: Feb 2020
Posts: 35
Likes: 0
Gotcha. I was thinking you were talking about that sensor with 4 wires that is on the proportioning(?) valve that has the brake lines hooked to it. I have ohmed the VSS at the sensor, at the plug up by the firewall and to the back of the PSOM, all 1400. I didnt have a chance today to unplug it and drive it. I will tomorrow is there a way to rig something up to drive it while seeing if it’s picking up the tone ring properly?
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
If you have a laptop computer you could hook it to a low cost scope (under $80.00) and have a look at the wave form.
Doing this while the truck is blocked with the rear end off the ground on jack stands and the rear end is turning about 30mph.
The manual says you can use the speedometer and if it is steady @ 30 MPH with the truck is blocked with the rear end off the ground on jack stands and the rear end is turning about 30mph.
From the shop manual:
Connect an AC voltmeter to Pin 4 (speed in +) and Pin 5 (speed in -).
Does the voltage increase smoothly and continuously from 0 to approximately 3.5 volts as vehicle speed increases from 0 to 30 mph?
OR,
If available, a frequency counter may be connected to Pin 4 (speed in +) and Pin 5 (speed in -).
Does the displayed frequency of the signal increase smoothly and continuously from 0 to approximately 666.7 Hz at approximately 30 mph?
OR,
If neither a voltmeter nor frequency counter is available, vehicle speed control may used as a good indicator. If it works normally, then the speedometer module is at least receiving a speed input signal and the wiring and sensor can be assumed to be good.
Does the speed control work normally?
Doing this while the truck is blocked with the rear end off the ground on jack stands and the rear end is turning about 30mph.
The manual says you can use the speedometer and if it is steady @ 30 MPH with the truck is blocked with the rear end off the ground on jack stands and the rear end is turning about 30mph.
From the shop manual:
Connect an AC voltmeter to Pin 4 (speed in +) and Pin 5 (speed in -).
Does the voltage increase smoothly and continuously from 0 to approximately 3.5 volts as vehicle speed increases from 0 to 30 mph?
OR,
If available, a frequency counter may be connected to Pin 4 (speed in +) and Pin 5 (speed in -).
Does the displayed frequency of the signal increase smoothly and continuously from 0 to approximately 666.7 Hz at approximately 30 mph?
OR,
If neither a voltmeter nor frequency counter is available, vehicle speed control may used as a good indicator. If it works normally, then the speedometer module is at least receiving a speed input signal and the wiring and sensor can be assumed to be good.
Does the speed control work normally?
Thread Starter
|
Freshman User
Joined: Feb 2020
Posts: 35
Likes: 0
Ok. The speedo works well at all speeds, steady up and down with no bouncing so I believe it is sending a good signal. It actually worked well before I changed the PSOM, but my ODO screen was barely legible so it was going to get fixed anyway. So I have a dumb question, where are pins 4,5? What plug is that and is there a description list of all the pins and what they are for future reference? I can read Hz on my meter and will perform this test and the AC meter test to be sure.
Thread Starter
|
Freshman User
Joined: Feb 2020
Posts: 35
Likes: 0
I used the DSS connection under the hood. Ohmed out at between 1700-2000. I think maybe my connection wasn’t the best as it was alligator clips onto a section of bare wire a couple inches before the plug. But the AC meter test started out smooth and increased to about 2.4 at around 23-24 and stayed there as I accelerated and went back down to zero smoothly as I stopped. The Hz test stayed at 0 til I hit 12-13 mph then jumped to almost 300, then smoothly increased as I accelerated. It was reading about 645-647 at 30 by my speedo. As I slowed down to 0 it smoothly dropped all the way back down to 0.
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
I think I would go to a salvage yard and get another PSOM and try it.
I would not trust a refurbished PSOM.
I am not sure how you would refurbished one anyway.
The ones I have worked with either had part fall off the board or a component burn up.
Mostly always in the upper left corner of the board but did have the large CPU come off of one.
I would not trust a refurbished PSOM.
I am not sure how you would refurbished one anyway.
The ones I have worked with either had part fall off the board or a component burn up.
Mostly always in the upper left corner of the board but did have the large CPU come off of one.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
Thread Starter
|
Freshman User
Joined: Feb 2020
Posts: 35
Likes: 0
I messaged the seller about maybe swapping it out and to see if he evaluated my old one to see if there was anything wrong with it. I am waiting to hear back now. Is there a procedure that I can use to test the unit myself?
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
I put one on the bench yesterday and tested it. Powered it up with my bench DC supply at 12VDC.
I used my sine wave generator to put this into it with the needle pointing at 30MPH.
And I got this out of it.
So I think it was a good PSOM.
Other than that I do not know any other way of testing it.
I used my sine wave generator to put this into it with the needle pointing at 30MPH.
And I got this out of it.
So I think it was a good PSOM.
Other than that I do not know any other way of testing it.
Thread Starter
|
Freshman User
Joined: Feb 2020
Posts: 35
Likes: 0
I am seriously considering buying a stand alone shift controller for the truck. It would eliminate this shift problem I am having plus it would be needed down the road if I convert from speed density to a carb anyway. Everything I am reading is saying how limited the speed density set up is for any type of performance and this truck is slow as molasses. I would like to wake it up a little. Any thoughts on a stand alone shift controller? I was looking at a US shift quick 4. It would give me control of all my shift parameters.
Logistics Pro
Joined: Mar 2005
Posts: 4,698
Likes: 47
From: Mexico, Missouri
Do you have any other PSOM to swap in?
As SubFord mentioned, the one with yellow marker shows a visual problem at the CPU.
I went through 3 PSOM's before I found one that got rid of my code 452 on my '95 Eddie Bauer, 4wd, Ext cab, 302. Did all the tests, checked everything, and still it turned out to be another bad PSOM.
I would get a hold of the Ebay seller and see if they have another known Good working PSOM they can send you to eliminate a possible problem with the one they sent you. There's no telling what was wrong with the one you received that was " Refurbished ". That is why I wouldn't accept anything that I didn't send in unless it was my last resort.
That brown discoloration shows evidence of something that may not be fixable or doesn't show up on their benchmark machine when testing.
As SubFord mentioned, the one with yellow marker shows a visual problem at the CPU.
I went through 3 PSOM's before I found one that got rid of my code 452 on my '95 Eddie Bauer, 4wd, Ext cab, 302. Did all the tests, checked everything, and still it turned out to be another bad PSOM.
I would get a hold of the Ebay seller and see if they have another known Good working PSOM they can send you to eliminate a possible problem with the one they sent you. There's no telling what was wrong with the one you received that was " Refurbished ". That is why I wouldn't accept anything that I didn't send in unless it was my last resort.
That brown discoloration shows evidence of something that may not be fixable or doesn't show up on their benchmark machine when testing.