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On the 452, I had read a dozen threads here and elsewhere then did my hybridized diagnostics. 1200 ohms across rear axle VSS. (some say 1000-2500 is correct, others say 190-250). Wiring had good continuity and no shorts in between RABS test connector and VSS. Went straight to the PSOM. It has a shorted diode and an overheated MOV. I'll make those repairs and then see if more diagnostics are in order.
Truck has had wonky transmission shifts since I got it. Didn't give it much thought since the truck obviously did not run at all well. But now, with the running issues solved, and with the truck running great, it became obvious that the shifting was not right. Then, while driving down the dual lane, I tried the cruise control. It engaged for about three seconds then disengaged. I got a flashing OD OFF (which had happened before) along with an audible alarm beeping with the OD OFF light. Then the truck stayed running but lost nearly all power. I don't remember what I did to reel it back in but was able to get the truck home under seemingly normal power.
Then we got hammered with fifteen inches of snow on January 25. My garage had to be made available for the vehicles I drive. I'm just now getting back to the project.
One section I refer to all the time is part of a TSB Ford issued years ago regarding speedometer pointer waver
J3 CHECK SPEED INPUT SIGNAL Connect Rotunda 88 Digital Multimeter 105-00053 or equivalent to Pin 4 (speed ) and Pin 5 (speed -). If available, a frequency counter may be connected to Pin 4 (speed in ) and Pin 5 (speed in -). CAUTION: Make sure multimeter is in the voltage function and not in the resistance function to avoid damage to multimeter. NOTE: Only wiring harness end of connector is to be probed.
Does the displayed frequency of the signal increase smoothly and continuously from 0 to approximately 667 Hz at approximately 48 km/h (30 mph)? OR does the voltage increase smoothly and continuously from 0 to approximately 3.5 volts as vehicle speed increases from 0 to approximately 48 km/h (30 mph)?
Yes REPLACE instrument cluster . SERVICE wiring.
No CHECK for open wiring. If no problems are found, REFER to Section 06-09A or Section 06-09B .
As a quick check you can snag the raw VSS signal at the RABS test connector under the hood instead of the connector at the PSOM. If the signal is good there, then tear into the dash.
My 1995 Ford PCED manual lists the VSS resistance as between 1300 and 1550 ohms (disconnected from the circuit).
My 1995 Ford PCED manual lists the VSS resistance as between 1300 and 1550 ohms (disconnected from the circuit).
Yesterday, at the U-pull, I pulled four VSS sensors. Two were 1800 ohms, one 900 something and one OL.
I just couldn't get to any OSSs on several of the transmission Code U vehicles (earlier than 2001) One I could get to was stuck fast and was just not going to come out with tools on hand and without damage (as in, probably snap in two)
Questions about OSS in transmission. Do the 4R70W and E4OD use the same sensor? Parts catalogs tend to say yes. What ohms should a good OSS be?
Tested the OSSat 467 ohms. Added the new diode and MOV to the PSOM board and slid the dash cluster back in. Ran the truck through all the shifts under different loads. Seems to be shifting perfectly.
One juror in my mind is not yet convinced but is coming around.
If the 452 code issues are fixed, well, that's great. After driving the truck and then moving it over to its designated parking spot, I couldn't help but notice a 6" diameter spot of antifreeze residue where it's been sitting for about a week.
The first surface mount component I ever soldered to a board (crooked piece next to Capacitor and new MOV). Good enough and way better than a disaster.
I do believe I need to pull the cluster back out. These four screws go somewhere
Last edited by diggerrigger; Feb 26, 2026 at 04:04 PM.
No difference in the PSOM. The transmission type has zero effect on how it operates. It's a frequency divider using the raw VSS signal from the rear axle.
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