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I was using Forscan to adjust my speedometer for my 37” tires on my late 99 f350 7.3, But the gem will not write the tire size (using the stock value 265/75R16) from the drop down menu, and gear ratio of 3.73. Tells me “writing blocks failed-incompatable configuration “. Same message even if I use the stock tire size. When I back out of the configbmodule page and return, values have returned to “incorrect value or not configured “. Cant get any value to write.
Of course, in Fte fashion, at the same time swapped my transfer case to a 271. Which gave me several more gem codes related to the shift motor, and the abs light came on.
Since the gem did not write the codes, I felt that I could have fried the gem. So i replaced it with the gem from the same donor truck where i got the 271.
No gem codes, abs light still on, no speedo, cruise, odometer, and my od button flashes.
Truck drives great, shifts normally, gives me no codes.
Gem still wont write, initial data field has same “Incorrect value or not configured” setting.
The “as-built” legend only has 52-01 FD88 1200 FFE9.
Replaced VSS, wiring checks out. Got vss resistance value of 1.87k ohms all the way up to the pcm.
Am I needing to change my as built data? if so, to what value?
Update… Drove the truck a good distance yesterday. It gave me the P0500 code. Od light still flashes.
I have replaced the vss sensor, twice… no change. The ohm readings are good up to the pcm.. I get a flat line on Forscan watching the vss while in drive.
If the sensor ring in the rearend was bad, would it not be intermittent on the speedo? cruise wont even turn on, no odo or speedo.
Ideas?
Tried the motorcraft service website. No GEM codes listed. Tried 2other vin’s also.
Pretty generic. But it has a disclaimer that it can be that way when specific data is not available, or vin isnt recognized.🤷♂️
Currently unsheathing my vss wiring from frame to sensor to check for anything weird. Pulled vss sensor, looked great, ohmed at 1.897k, connector in great shape. Reluctor looks great also. sensor was clean when pulled. Grabbed a spare new sensor off my shelf, seated fully against diff housing by hand..
I think you download the entire file by selecting the download button. It will be an .ab file but I don't have a forscan to see how to access the file and then use it to load the as-built into our vehicles.
I think you download the entire file by selecting the download button. It will be an .ab file but I don't have a forscan to see how to access the file and then use it to load the as-built into our vehicles.
Tim M
Ill try that out. I just figured it was the same info as displayed. Thanks Tim.
Looking forward to your progress. If the Forscan has a way to load the .ab (as-built) file, I may have to try it myself for my issue with the VSM in my Excursion. I think this will fix my keypad not working on my vehicle without taking it to Ford.
Had a bit of a pause. Family stuff to take care of...
I downloaded the .ab File.....evidently an android program. I seen a you tube video on how to open it with the forscan, and will try it out soon.
The VSS harness was clean, all values within spec at the ABS connector. Seeminig like the VSS signal is just not getting to the PCM or GEM for some reason... Checking the wiring from the ABS module (rear abs only) found the Lt Blue with White stripe wire has a 20-55 ohm resistance value from the ABS connector to the Data link connector. It should'nt have any. tracked it down to the lower firewall connector, section from firewall to abs is good, now reading 37 ohm from firewall connector to data plug (OBDII). Seems straight forward, ties into the pcm, but still is a direct path (diagram wise) to the data link from the firewall connector. The ohm value was changing when I messed with the firewall connector, but no corrosion is present. UGH... Now gotta look under the dash to see if the wiring is compromised somewhere...
Having second thoughts on the donor GEM.....Have not swapped the original back in yet. If the donor GEM is from a gasoline model, regardless of the year truck, would'nt it have different programming for the speed sensor signal processing?
I recall there being an additional module in the gassers...
