I have a 1993 F150 5.0 AOD with a cluster W/tach that the oil gauge has gone out and the speedo only goes to 85. I want to know if a cluster set from a 92 or 93 lightning will work plug and play or if it needs to be calibrated for the 120 MPh speedo??

 

Year for year will swap in.
Yes you'll need to recalibrate the speedo. Maybe swap the psom (I think that's the name)

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120 speed will not do you any good since these trucks shut down at 95mph

 

You can put a divide by 2 chips between the PSOM and the PCM Computer and then the truck will shutdown at 190mph.
If you get a cluster from a 92 or 93 then it would be plug and play. I guess they had a Lightning in 92.

 

No only 93, 94 and 95

Good to know on the divide

 

The PSOM in our trucks is a divide by 10 and in the F53 is a 1 to 1 or no divide with the CAL set to 1.0. Same PSOM is used in both.
Our trucks with normal size tires when the computer sees 66.7Hz it thinks you are going at 30mph, 133.4Hz 60mph & 200Hz is 90mph.

I thought that 200Hz or 90mph was the shutdown. I will have to look at this closer with the scope, frequency generator and frequency counter.

 

Doesnt that all change with the F350s larger 235/86/16 tires?

 

The 16 inch tires on my F53 (F550) uses the 1 to 1 no change frequency as the VSS is mounted on on the parking brake housing. I tested it yesterday at 66Hz to the PSOM and the speedometer pointed at 30mph.

With a F150 an a CAL of 972 and stock tires with 667Hz going into the PSOM the speedometer will point at 30mph. Different size tires will change the frequency some going to the PSOM but when you put the CAL in for the size tires (rotations per mile) the PSOM will do the math an still send 66.7Hz to the computer @ 30mph.

 

Just remember you have only 6 changes to the CAL before it will not change any more. But we are working on that.....

Also the divide by two IC on the PSOM to ECU will work with the AOD and manual trannys only. The E4OD will not shift right as the ECU will see half of the speed.

 

It should also work with the 4R70W as its computer does not seem to use the speed input from the PSOM for shifting. I drove for a few days with a dead PSOM and had no problem with shifting. It must use the output shaft sensor (OSS) for shifting the 4R70W transmission.

I have never seen a post on this site about hard shifting related to the PSOM for the 4R70W.

 

I never messed(yet) with the AODE/4R70W transmissions so I don't know how they behave with missing PSOM speed info.

Most trucks usually have the E4OD on the ones I worked on.

 

1992-1997 trucks with E4OD and the VSS mounted on the brake housing like my 1994 F53 use the PSOM for the speedometer only. The PCM computer does not use the PSOM information at all.
On these trucks and class "A" RV's the VSS sends the speed information directly to the PCM Computer, PSOM and also the speed control module as the speed information the VSS generates is all ready at 66Hz at 30mph.

This is the same way the 1989-1991 F-series trucks with the E4OD used the speed information from the VSS to the computer for the E4OD shifting that did not have the PSOM.

1992-1997 with VSS mounted on the brake housing:


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Who's "we"?
You got an engineering team on this?

I ain't set up to read/write chipsets since I mostly work with PLC's/PAC's, but have considered trying to dig around in the PSOM and seeing what I can find. Let me know if I can help y'all any.

I would be happy finding whatever register holds the number of changes, and writing zero to it. As long as there ain't any logic in there that watches out for that value to decrease lower than the previous value (giving the ERROR message), we can have unlimited changes.

EDIT: or better yet, just make it so changes are allowed as long as the total number or changes is less than something really high. Assuming an 8 bit register we could set that at 255... and if you change your cal THAT many times... you have more money for tires/gears than I do

 

That's what's kicking my brain right now.... PARITY check or CRC. Just can't 00 out/FF out a location as it will Error the odo.