So I need to find a wire!! I'm getting the Painless Wiring 30140 fan control unit and it has a function that taps into the VSS and it will turn off the fans above a set speed. I have some wiring diagrams for the truck but can't find anything about a VSS. What I did find (on the diagram; haven't looked under the truck yet), is there is a Ouput Shaft Speed Sensor (OSS) on the tranny that has two wires. In the manual for the controller, it references two wire sensors. The fan controller wire needs to tap into the "high side" wire from the speed sensor.

If it's relevant, there's also a Transfer Case Speed Sensor, but I'm guessing this one doesn't matter…or does it.

So, two questions then…is the OSS the same thing as a VSS in that it provides the signal to the speedometer or ECU?? I can't decipher this from the electrical schematic.

Also, if this is the correct sensor, which wire is the high side wire?

Sorry…I tried like crazy to copy the page from the book but couldn't get it…I'll keep trying.

Here's a link to the manual for the fan controller.

http://www.painlessperformance.com/Manuals/30140.pdf

 

There's an easy test - unplug it and see if the speedo works.

 

And to add insult to injury…the wiring diagram shows the OSS sensor on the left rear of the tranny…I've been all under the truck and can't see a single sensor with wires or a connector anywhere on the tranny…WTF??

 

To be a vehicle speed sensor on a 4wd, it's going to have to be on the transfer case or rear axle - think about it.

Hint - 4 low........

 

Yea, that would make sense, but don't see anything listed. I found the OSS sensor BTW. It's the only thing that makes any sense though. You can see the OSS on the bottom right of this schematic with the wire going to the powertrain control module, which has the output for vehicle speed.



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Probably need to contact Painless tech dept and see if they know about this particular vehicle. There's also a Turbine Shaft Speed Sensor and a Transfer Case Speed Sensor (both of which are listed as being on the tranny BTW), but I can't find anything on a wiring diagram that shows either one of these providing vehicle speed like with the OSS.

 

I would disconnect it and see what happens but I can't confirm on a schematic where this runs the speedo, or if it affects anything else. Guess I'd find out if I drove it, LOL.

 

I'm not that familiar with the vehicle speed sensor on an F-150, but I think it is on top of the rear axle, near the center of the truck.

 

There is an electrical connection on the front of the axle, just about center, on the driveshaft side. But I didn't see any mention of it on any of the electrical schematics I looked at…will do some more research. Thanks though…forgot all about that one being there. Will look to see if I can at least figure out what it is exactly.

 

Nope…the only sensor on the axle of this is the RABS…rear anti lock brake system.

 

Yep, that's where mine is. I have one on the T-case as well.

OSS+VSS

That's for a 98 E4OD 4x4 tho. Galaxy prob has the 4r70w and obviously a newer model.

 

Yep, that's the vehicle speed sensor.

 

Wow, seriously??!?? Not arguing (cause I don't know), but I cannot find anything in the factory wiring schematics that show this to be true or related. If it is so, then do you by chance know which wire is the "high" wire? The instructions say to tap into the high side wire from the VSS sensor. Thanks guys.

 

No, I don't know which is the high wire.

 

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OK, so here's a couple more schematics. You can see the rear axle speed sensor on the anti-skid schematic, but it doesn't label the pins where the two wires go. Plus, they go to the anti-skid control box; nothing here indicates a reference or connection or input to provide vehicle speed.

However, on the cruise control schematic, you can see the wire from the output shaft speed sensor on the tranny does, if you follow it. I'm guessing this is going to be my wire. Although I would make a guess that either would work as it's only using the signal as a reference. The ABS sensor on the axle obviously provides a speed signal to something, so I bet it would work as well. Oh well.






Also copied this from an older post on a similar subject which led me to think the OSS wire is where I want to go…

For F150 late model 99's and newer.

output shaft sensor (OSS) Located at the Driver's side Tailpiece of the 4R70W/4r100/M5r2 transmissions and used for the Shifting, etc on the Automatic transmission. Also used on the Manual M5R2 transmission. Input is on PCM's Pin #84 a Dark blue with a yellow tracer wire.

Turbine Shaft Speed (TSS) Sensor, used in conjunction with the (OSS) for 4R100 transmissions.

vehicle speed signal (VSS) computed and massaged from the (OSS)signal in the PCM and output is on PCM's pin #68 a Gray with a Black tracer wire. Used for Vehicle's speed control unit, etc.

The Cluster odometer/speedometer readout is multiplex'd on the communications data highway (SCP network) and handled by the microprocessor in the cluster unit.