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Mark are you talking about the connection to the variable speed sensor on the differential? Is that where you are saying test with the ohm meter? If it shows a short,then follow those wires back to the computer?
You need to check the wires from the PCM (the truck's computer) to the VSS (Vehicle Speed Sensor) on the differential. You can't check the wires just at one end, it won't show you anything useful.
Has anyone put a Oscilloscope on the test connector for the VSS and see what its doing? The VSS test connector gives raw VSS signal. If that signal is good, next thing to do is to test the connector on the cruise control servo.
You can also read the full post for context, I know it seems odd
I have. There is no VSS “test connector” in the schematic he provided in post #10. He could be talking about is the RABS data link connector but you don’t need to do that. Follow the procedure Mark laid out. You could backprobe the wires at the speed sensor to see if it is producing voltage when turning.
This is the VSS test connector. In the schematic, ford calls it the RABS DATA LINK, but I've never been able to get data from it. The VSS test connector goes directly back to the VSS sensor and provides raw VSS signal. I assume ford put it there so techs didn't need to crawl under trucks to see if the VSS is working. Ford's spec is 800-1400 ohms, IIRC. Mine is running a little low at 623 ohms. If I connect up a O-scope and turn the tires, it'll show a ~4v square wave.
This is the VSS test connector. In the schematic, ford calls it the RABS DATA LINK, but I've never been able to get data from it. The VSS test connector goes directly back to the VSS sensor and provides raw VSS signal. I assume ford put it there so techs didn't need to crawl under trucks to see if the VSS is working. Ford's spec is 800-1400 ohms, IIRC. Mine is running a little low at 623 ohms. If I connect up a O-scope and turn the tires, it'll show a ~4v square wave.
so as long as its connected (wire issues) you can use it. and presumably if you get an ohm reading on it, it should be connected. only if that or other freak issues show up would you have to check by the diff.
But what is that connector look like? I dont think my truck has a plug like that(cant tell well) under my hood
According to my Ford EVTM manual a 1996 model year F-Series truck should have that RABS Data link connector (C143) located on the bracket near the driver side hood hinge just like the earlier model year trucks.
Thanks guys. I’ll keep all of this in mind in the case this doesn’t work, and i’ll probably try to go ahead and get the oscillator. I’ll also check tomorrow to see if i have the RABS connector. Do you know if the XL’s on a 250 usually came with it?
According to my Ford EVTM manual a 1996 model year F-Series truck should have that RABS Data link connector (C143) located on the bracket near the driver side hood hinge just like the earlier model year trucks.
IS the plug the same? Im curious now lol. I havent seen it before, but it may be tucked behind some stuff back there. But Strange its not hanging out up there
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